INTRAORAL RADIOGRAPHIC POSITIONING DEVICE - AN IN VIVO AND VITRO STUDY
Dissertation submitted to
THE TAMILNADU Dr. M.G.R. MEDICAL UNIVERSITY In partial fulfillment for the Degree of
MASTER OF DENTAL SURGERY
BRANCH III
ORAL AND MAXILLOFACIAL SURGERY APRIL 2018
This is to certify that this dissertation titled “EVALUATION OF PLACEMENT ACCURACY AND ANGULATION OF DENTAL IMPLANT USING INDIGENOUS STENT AND INTRAORAL RADIOGRAPHIC POSITIONING DEVICE - AN IN VIVO AND VITRO STUDY” is a bonafide record of work done by Dr. G. KARTHIK RAJAN under my guidance during his postgraduate study period 2015 -2018.
This dissertation is submitted to THE TAMILNADU Dr. M.G.R. MEDICAL UNIVERSITY, in partial fulfillment for the degree of MASTER OF DENTAL SURGERY in Branch III – ORAL AND MAXILLOFACIAL SURGERY.
It has not been submitted (partially or fully) for the award of any other degree or diploma.
Professor, HOD and Guide Principal
Dr. L.DEEPANANDAN, M.D.S., Dr. V. PRABHAKAR, M.D.S., Department of Oral & Maxillofacial surgery, Sri Ramakrishna Dental College & Hospital, Sri Ramakrishna Dental College & Hospital, Coimbatore.
Coimbatore.
Date:
Place: Coimbatore
I hereby declare that the dissertation entitled
EVALUATION OF PLACEMENT ACCURACY AND ANGULATION OF DENTAL IMPLANT USING INDIGENOUS STENT AND INTRAORAL RADIOGRAPHIC POSITIONING DEVICE - AN IN VIVO AND VITRO STUDY is a bonofide and genuine research work carried out by me under the guidance of Dr.L.DEEPANANDAN M.D.S, Professor and H.O.D DEPARTMENT OF ORAL AND MAXILLOFACIAL SURGREY, SRI RAMAKRISHNA DENTAL COLLEGE AND HOSPITAL, COIMBATORECandidate
DR. G.KARTHIK RAJAN
Department of Oral and Maxillofacial surgery Sri Ramakrishna Dental College and Hospital Coimbatore
Date:
Place:
Urkund Analysis Result
Analysed Document: thesis final intro - conclusion.docx (D35071264)
Submitted: 1/27/2018 9:23:00 AM
Submitted By: karthik.rjn09@gmail.com
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This is to certify that the dissertation work titled entitled
EVALUATION OF PLACEMENT ACCURACY AND ANGULATION OF DENTAL IMPLANT USING INDIGENOUS STENT AND INTRAORAL RADIOGRAPHIC POSITIONING DEVICE - AN IN VIVO AND VITRO STUDY of candidate Dr.G.KARTHIK RAJAN with registration number 241515301 for the award of MASTER OF DENTAL LSURGERY in branch of ORAL AND MAXILLOFACIAL SURGERY. I personally verified the urkund.com website for the purpose of plagirism check. I found that the uploaded thesis file contains from introduction to conclusion pages and results shows 0% of plagirism in dissertation.Guide & Supervisor sign with seal.
Dr.L.Deepanandan M.D.S Professor & H.O.D
Department of Oral and Maxillofacial Surgery
Coimbatore.
First and foremost, I would like to express my sincere gratitude to my guide Dr. L. Deepanandan, M.D.S., Professor and Head, Department of Oral and Maxillofacial Surgery, Sri Ramakrishna Dental College, for his unwavering guidance, for his patience, motivation, enthusiasm, and immense knowledge. His guidance helped me in getting a better shape during the time of my course, to understand and complete the dissertation. I could not have imagined having a better guide for my dissertation.
I also express my sincere heartfelt gratitude to Dr. M. S. Senthil Kumar, M.D.S., Professor, Department of Oral and Maxillofacial Surgery, Sri Ramakrishna Dental College, for his constant support and encouragement throughout the duration of my course, scholarly support throughout this journey.
I also express my sincere heartfelt gratitude to Dr. R. Kannan, M.D.S., Professor, Department of Oral and Maxillofacial Surgery, Sri Ramakrishna Dental College, for his innovative ideas, suggestions, valuable criticism and constant encouragement throughout the duration of my course.
I also express my sincere heartfelt gratitude to Dr. M. A. I. Munshi, M.D.S., Reader, Department of Oral and Maxillofacial Surgery, Sri Ramakrishna Dental College, for his constant scholarly support, guidance and encouragement throughout the duration of my course.
I also express my sincere heartfelt gratitude to Dr.R.S.Karthik, M.D.S. Reader, Department of Oral and Maxillofacial Surgery, Sri Ramakrishna Dental College, for his help, support and inspired me through this period of dissertation work.
Maxillofacial Surgery, Sri Ramakrishna Dental College, for their valuable help, support and guidance.
It would be unfair of me if I fail to acknowledge the timely help and constant encouragement from my colleague Dr.N.Santhoshi Revathy, whose support helped me to overcome difficulties.
I also express my sincere thanks to my beloved seniors Dr.V.Krithika, Dr.M.Geetha and Dr. Gayathri R Nair for their guidance and co-operation during the course.
I also express my sincere thanks to my beloved juniors Dr.S. Harshad, Dr. A.Preethi and Dr.S. Shalini for their help and support.
Above all, I wish the Almighty for blessing me with such wonderful grandparents, parents and my wife. Their support, love, sacrifices and encouragement have made me to achieve my dream.
I thank the Almighty for guiding me throughout my life.
Dr.G. KARTHIK RAJAN
ABSTRACT
AIM:To design an implant angulation positioning device for radiographic and surgical placement of dental implant, as the angulation plays a vital role in prosthetic loading and aesthetic outcome.
MATERIALS AND METHODS:
An implant angulation position device was designed for implant placement in partial and completely edentulous area in planned buccopalatal/ lingual angulations, A surgical stent was designed using guide sleeves in thermo vacuum press, which was evaluated for radiographic and surgical implant angulations. 10 implants in alloplastic models and 2 clinical cases were evaluated for implant angulations.
RESULTS:
The tabulated results for the determined and achieved angulations were calculated statistically. The results showed that the mean percentage error between the determined and achieved angulations was 0.048o, and no statistical significance under Student ‘T’
test.
CONCLUSION:
An angulation positioning device and a dual purpose surgical stent was designed as completely limiting design stent and evaluated. The results showed no significance between determined and achieved angulations.
KEYWORDS:
Implant, angulation, angulation positioning device, stent.
TITLE PAGE NO.
1. Introduction……….. 1
2. Aim & objectives………. 4
3. Review of Literature………. 5
4. Materials & Methods……… 22
5. Figures……….. 35
6. Results……….. 42
7. Discussion……… 50
8. Summary & Conclusion……….. 61
9. Bibliography………. 62
INTRODUCTION
1
The placement of dental implants in a functional and esthetic position is considered to be a challenge in spite of major advances in surgical techniques and devices available. The alveolar bone loss and adjacent tooth makes the implant placement difficult in the proper or ideal position. The angulation of implants plays a vital role to the outcome. It is important to place the dental implants in a correct angulation and position in relation to each other, teeth, and to the underlying bone, as the alveolar bone loss following tooth extraction often makes ideal implant placement difficult 1. The non-axial loading of implant-supported prostheses may occur due to incorrectly positioned and non- parallel dental implants which may result in improper occlusal load distribution of the implant leading to failure of osseointegration 1,2. The, parallelism between dental implants supporting the over dentures is important to achieve complete seating of retentive elements, predictable attachment retention, prevention of premature wear of the involved components, and provision of axial loading 3 .
The most important factor leading to dental implant failure after fabrication of prostheses is overloading; therefore, successful implant placement requires accurate positioning and angulation to achieve a predictable aesthetic result and resistance to heavy occlusal forces 1,4. According to Sabb et al 2, 20 percent of implants which were located too far palataly had bone loss greater than 2 mm.
The surgical guide is an effective tool to ensure the communication, which is required with regards to the implant position, between the restorative dentist and the surgeon. Using a surgical guide helps to provide guidance for implant placement in the ideal mesiodistal position if the guide is fabricated according to correct artificial teeth setting in the diagnostic model 5. Failure to use a surgical guide is considered one of the etiological factors related to prosthetic complications after implant insertion. It is necessary to accomplish the planning phase, using appropriate radiographic and study
2
cast examination before implant placement and surgical guide fabrication,. All the details accumulated can provide comprehensive information regarding the three-dimensional anatomy of an implant site 6.
The angulation of the implant can adversely affects the esthetic outcome in the anterior region. The implant abutment must be planned and placed to resemble the natural tooth preparation. Poor implant angulation (too much towards the palatal or the buccal) in case of screw retained prostheses can alter screw placement and compromise the outcome and esthetics.The teeth adjacent to the implant site if present in good alignment it is acceptable, to place the implant in the angulation7.
A 2-dimensional periapical radiograph has been the standard in dentistry for aiding clinicians in the diagnosis and treatment planning for various procedures including, but not limited to, the detection of dental caries, identifying pathology, periodontal disease, endodontic treatment, need for tooth extraction, and locating receptor sites for dental implants The advent and acceptance of 3-dimensional computed tomography (CT), and newer-generation lower-dose cone beam computer tomography scan devices (CBCT) in combination with interactive treatment planning software provides the clinicians with the ability to truly appreciate each patient’s anatomic reality. Regardless of the device used to acquire the dataset (CT vs CBCT), it is imperative that there is an understanding of how each image can provide important undistorted information that can be used for diagnosis and treatment planning for a variety of surgical and prosthetic interventions to improve accuracy and limit complications. Generally, the 3-dimensional dataset consists of 4 basic views: (1) the axial, (2) the cross-sections, (3) the panoramic reconstructed view, and the 3-dimensional reconstructed volume. Each of these views is important, as no one view alone should determine the ultimate desired treatment 8,9.
3
Despite significant advances in devices and techniques, placement of dental implants at a correct position as per the esthetic, biological, and functional perspective still remains a challenge, because the trajectory of implants is seldom consistent with that of natural teeth due to the bone loss that follows extraction.
AIM & OBJECTIVE
4 AIM:
1. To design an implant angulation positioning device for radiographic and surgical placement of implant.
OBJECTIVE:
1. To evaluate the device accuracy in implant guide angulation position through radiographic stent.
2. To prepare a surgical stent using the angulation device and evaluate the accuracy of the angulation of implants placed.
REVIEW OF LITERATURE
5
Young et al (1985) 9 compared heat-cured moulded acrylic resin, auto polymerizing compression moulded acrylic resin, auto polymerizing acrylic resin with tin foil substitute separator and thermoplastic vinyl resin with positive and negative pressure adapted to the cast. And found out that the preference was equal between heat cure molded acrylic resin with foil and thermoplastic vinyl resin with positive pressure
Thomas J.Balshi, Don G.Garver. (1987) 30 classified and discussed the stents used for implant placement, depending on the dentition available as 1) fully edentulous 2) partially edentulous and 3) partially edentulous tooth supported design. The designs were used to plan the axis on cast and placement of guide sleeves in template for implant placement.
M.J.Edge (1987) 33 recommended the use of surgical guides for implant placement surgery. Which allows the dentist to treat patients with minimal communication loss and achieve a result desired by both. He also mentioned that the surgical stents can greatly facilitates planning and achieve the outcome of the implants in the originally planned area.
David R Burns et al (1988) 12 found a technique to calculate the bone width and gingival height at the site of implant by anaesthetising the region and inserting a 25 gauge needle perpendicular to the soft tissue until it hits the underlying bone. The distance from the point of insertion into the soft tissue was measured on the buccal and lingual aspect at frequent intervals, to determine the amount of bone width available.
F. Modica et al (1991) 13 designed a device known as “positioner of perforation guides,”
it consisted of (1), a curved scale (-20 +20 degrees) around with an arm holding a pin, which can slide varying the pin’s inclination and (b), a horizontal scale, which was connected to one end of the Curve scale assembly, which could slide in a guide, (c) the guide connected to a vertical rod, which is fixed with a normal parallelometer, and a
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vertical graduated scale indicates the height of the device. The devise was used in dummy mandibles to place the implant guide sleeves in determined angulation after computer tomography readings. The study showed a mean horizontal error of 0.4mm and mean angular error of 1.3°.
Jeffery L.Tarlow (1992) 26 proposed a technique for edentulous mandibles, in which the patient’s denture was duplicated with transparent acrylic resin and a clear polypropylene stent was made over it in a vacuum-forming machine. In the process the whole anterior segment of the duplicate denture was removed in order to expose the surgical area and the vacuum stent was perforated at the planned implant sites and adapted over the denture for drill guide. The surgical templates were relieved at the buccal flange to fit the reflected flap, and the lingual flange trimmed to allow easier access to the surgical fields as the template would be supported mainly by the patient’s mandibular pads and remaining tissues. The stent can be removed and replaced easily during surgery, leaving the duplicate denture in place. The desired fixture location is thereby obtained with minimal interference to surgical access.
Adrian ED et al (1992) 36 described a new implant placement guiding technique using a surgical guide that gives both implant location and trajectory to the surgeon with the help of radiopaque markers which resulted in consistent programming the implant fixtures for ideal prosthodontics replacement . The radio graphic markers were placed on the diagnostic dentures and a lateral cephlometric radiograph was made which showed the osseous anatomy at the symphysis and anterior tooth location. The ideal implant location and trajectory data obtained were transferred to a surgical stent confirming the anglulation and location of the fixtures at time of surgery. The stent also acted like an occlusal rim, a mouth prop, and tongue retractor.
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Neidlinger et al. (1993) 50 described a technique for the fabrication of a modified surgical guide preserving only the vestibular part of the planned stent instead of holes or grooves placed on the lingual flange of a duplicated denture. The stent allowed better control of the implant buccal/lingual angulation and their placement in an optimal position for prosthetic rehabilitation.
M S Reddy et al (1994) 14 did a comparison study between panaromic imaging and computed tomography and inferred that the magnification and distortion phenomenon, lack of sharpness are absent in computed tomography. The orthopantamogram showed a measurement difference of 4.7-5.0 mm compared with computed tomography.
Garber DA (1995) 17 coined a terminology “prosthetically driven implantology”, and emphasised on the need of aesthetics and predictable prosthetic treatment results which establishes that the optimal position of implants is related not only to internal anatomy, but also to biomechanics and the final prosthesis design.
Michael J Engelman et al. (1998) 48 compared the magnification factor and location identification for implant using metal markers with lateral cephalogram, orthopantomogram and computed tomography. The magnification factor was 50 % - 70
% in horizontal axis and 10 % - 32% in vertical axis and the assessment of bone quantity and quality can be done effectively. The computed tomography showed good correlation but artifacts and scattering effects were present when used with metal markers.
Thomas Fortin et al (2000) 37 the template is designed with a drill which travels in the main axis of the resin tooth and gutta purcha added to make it visible. A cube is made of acrylic resin with two titanium tubes in highly precise position in the stent which lies outside the mouth in front of the lip. The template is placed on patient and subjected to computerised tomography. The findings are evaluated using three planes: the axial slice
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and two reformatted views. One of these latter two views is perpendicular to the arch of the jaw, the other is tangential, and they both not only intersect with but pass by the fixture axis. Making alteration in the axial axis of implant with the check of shape of jaw and fixing it in ideal angulation in the three-dimensional volume and claim significant improvement over previous technique because it gives a precise evaluation of the implant dimensions to be transferred.
Minoretti et al. (2000) 5 presented a novel surgical guides technique for implant placement, where after planning and fabricating the stent. Kirschner wires (0.8mm) are placed through the mucosa as reference for an osteotomy with proper location and angulation through the guide hole in the stent before flap reflection. A 3.5 mm ITI trephine drill follow the wire and angulation to complete the osteotomy. The only disadvantage was the drill may not completely concentric with guide wire in some cases.
Sicilia et al. (2000) 16 evaluated the outcomes of the implants position, placed with the aid of fixed or movable surgical templates in slightly resorbed edentulous maxillary arch . The results showed coincidence of abutment screw position 38% in removable and 61%
in fixed stent. The invasion in tooth contour was a significantly higher frequency of coincidence between the planned implant positions and the ideal emergence positions that's 25.7% compared with 0.04%. By analysing the results they concluded that the use of fixed surgical stunts can reduce aesthetic, implant placement problems and allow the dentist to achieve best possible results.
J. Robert Spray et al (2000) 6 studied on influence of bone thickness and said that a high percentage of implant failures and marginal bone changes occurred between the time of implant placement and placement of the final prosthesis. The facial plate thickness was examined and found that there was a slight failure when it was more than 2 mm bone than 1 - 2 mm and less than 1 mm, in the the failed implant segment. The failed implant area
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showed a 2.8 + or - 1.5 mm compared with survived , exhibited 0.7 + or - 1.6 mm. The implant failure was inversely proportionate with the bone availability and the type IV bone showed less bone loss in HA coated than non HA coated implants.
Almog DM et al (2001) 42 reviewed methods for identifying the placement implants in surgical guide fabrication. He evaluated the results of different markers like o gutta- percha, vertical lead strips, set-up disks and metal tubes and concluded that different approaches for surgical guide fabrication emphasis on stability for successful placement and stabilising by mini-implants, can be very useful especially in completely edentulous ridges.
Peter Y. P. Wat et al (2002) 46 said that a radiographic template carries both clinical and radiographic information of the fixture angulation, location and transferring the information to surgical template or stent leads to successful implant placement and concluded that the transfer of the radiographic information to the surgical template remains a challenge.
Simon H (2002) 34 studied the long term success of implants, comparing the complexity of surgery and prosthetic reconstruction. He suggested that the radiographic/surgical templates, surgical guides for dental implant placement should ensure adequate implant orientation into the bone tissue, according to the patient`s anatomy and restorative treatment planned which reduces the risks associated with complex surgeries and difficult prosthetic reconstruction and increase the long-term success rates of the treatments with implants.
Kevin C. Kopp et al (2003) 41 evaluated the practiciners ability to assess the quantity and quality of bone and critical anatomic structures before surgery using tomography and computed tomography (CT). These advanced radiographic techniques allowed better bone
10
evaluation but less orientation to an implant specific site by the practitioners. Determining the relationship between the final restoration and available bone was difficult. The use of CT scan with intra-oral template containing radiopaque markers like ball bearings and gutta percha, assisted in identifying the pending implant site and to calculate the percentage of radiographic magnification. Thus providing greater clinical correlation and confidence on placing implants.
. Fujio Tsuchida et al (2004) 40 studied on diagnostic templates which can be modified as surgical templates by transferring radiographic information. Silicone materials used for impressions and maxillomandibular records are used as radiopaque contrast markers on diagnostic templates, which allow them to be easily removed and attached.
Radiopaque silicone markers serve as a guide for achieving a 3-dimensional evaluation of the bone, without artefacts in CT scan, can be easily transformed to the surgical guide by removing the marker. The 3-dimensional template design and marker provides guidance for accurate implant placement.
Stephen M Parel, R.Gilbert Triplett (2004) 43 said that interactive computer imaging technology allows implant to be planned virtually with significant advancement over conventional computed tomography data. The acquisition of the imaging requires more time than conventional technology, to plan the implant placement precisely, in relationship to the anatomic structure and the final prosthesis. After finalising the plan the data is used to construct a precision surgical guide splint and the final prosthesis.
Maher MM et al (2004) 19 said that the dose of radiation applied to perform diagnoses with CT scans and its long-term consequences are, currently, under intense debate. He advocated that Clinicians and patients should have a clear idea regarding the risks of the radiation involved in CT scans. The radiation from CT scan machines are currently higher
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than that of a conventional dental radiograph. Hence, it is important to define an effective, low dose radiation that leads to a quality image
Jurgen Hoffman et al (2005) 44 studied the accuracy of navigation socket software and found that the degree of accuracy mainly depends on CT layer thickness 0.75mm thickness slice , voxel size 0.39mm3 of object to image registration. He also concluded that the benefit of the navigation technology relies on the ability to control depths, position and angle of the implant and also helps to relocalize the position of implant after the healing period.
Simon Yeh et al (2005) 39 suggested use of transitional implants with minimal of 3mm engagement in bone can serve as template stabilizing unit, during surgery for more accurate placement of implant and provide interim support for a provisional prosthesis during the integration phase of the conventional implants.
Michael P Gilizia et al (2005) 3 investigated the importance of the parallelism between dental implants in supporting over dentures and tested it on gold and titanium matrices which were placed on ball abutments in different angulation ( 0, 10, 20, 30 degrees). The results showed 25% decrease in reduction in retention in 30 degree positioned implants, which was not a significant clinically to use other expensive and complicated implant over denture attachments.
Yajima A et al (2006) 8 examined that maxilla and mandible requires the equivalent amount of radiation necessary for a radiographic full-mouth periapical series, but with higher longitudinal and axial resolutions . It differs from the conventional CT machines in aspects, such as weight, cost, scan time, and the final resolution of image and its voltage ranges from 60 to 120 KV at 20 KV intervals with a tube current of 10 - 15 mA.
The software are capable of displaying processed images such as multiplanar reconstruction (MPR), volume rendering (VR), surface rendering (SR), maximum
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intensity projection (MIP), cross sectional and partial panoramic view. Different modes like I - mode ( 0.2 mm with a 4 in diameter) , D- mode ( 0.1 mm with a 2 in diameter) with 4 to 7 inch diameter sensitive area with scan time of 9.6 sec and 288 projections in 380 degrees. It has been the examination method of choice for preoperative purposes, especially when the benefits to the patient compensate for the risks of the exposure to ionizing radiation.
Ozan O, Turkyilmaz I, Yilmaz B.(2007) 51 concluded that there was no significant bone resorption changes ( p= 0.38) with the use of flap less and conventional procedure for placing implant through guide surgery. Bone visualisation helps the surgeon to make a final decision regarding bone availability and quality, which may influence the implant treatment outcomes. He also recommended flap less procedure as alternate as there is reduction of post-surgery undesirable instances, such as discomfort, pain and swelling.
Xavier Sabb et al (2007) 2 measured and compared the strain distribution on the bone around an implant in the anterior maxilla by means of finite element analysis in straight and angled (20 degree) placed abutments. The implants 4 X 13 mm were placed at an angle of 113 degrees to ANS - PNS line with the implant abutment complex was moulded and producing 130 degree relationship with the long axis of implant when a load applied near to the cingulum. The study concluded that the principle strain was found 4650, 4020 micro strain in implant bone interface cancellous bone interface, small areas of strain higher than 4000 micro strain in most apical micro threads on the palatal aspect and 1000 - 3000 micro strains were seen in implant body on both buccal and palatal models with a magnitude force of 178 force was applied.
Amar Katranji et al (2007) 11 examined the cadavers with dentate and edentulous and said that in the edentulous maxilla the cortical thickness ranged from 1.04 to 1.69 mm buccaly and from 1.36 to 2.06 mm palatally , and in mandible, ranged from 1.66 to 2.39
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mm; with the thinnest area in anterior maxilla and thickest in posterior mandible. In the dentate maxilla they buccal cortical thickness was 1.59 to 2.23mm and a lingual cortical thickness of 1.95 to 2.35 mm. The dentate mandible showed buccal and lingual cortical measurements as 0.99 to 1.98 mm and 1.24 to 2.51 mm, respectively and the thinnest area in lower anterior region, and thickest in posterior mandible.
Trevor Bavar (2008) 32 said that the surgical guides have been created with the aid of computer-assisted tomography (CT) technology which allowed 3-dimensional reconstruction of the area of interest. For implant surgery. The Cross-sectional slices correlated with panoramic views and axial slices of computed tomogram provided accurate representation of the patient’s jaws in constructing the prosthesis and surgical guide. Radio-opaque markers are used into the radiographic guide to be scanned by the the patient wearing the guide to determine the angulation and site of implant.
Manuel O.Lagravere et al (2008) 20 compared that of 3D CT and manual measurements on skull which was found to be was accurate up to 99.72% and concluded that CT produced an accurate image of the object scanned. They also added than even though the 3D volumetric imaging provided a 1-to-1 ratio, clinicians intended to analyse by visually identifying the structures, without using exact measures or other quantitative analysis.
Vercruyssen M et al (2008) 7 studied the construction of surgical template in transferring the computerised tomography image to the surgical field. He also analysed varies methods and materials used to construct the radiographic and surgical stent and used silicon index to transfer the axial inclination planned in computer tomography. He suggested that the guide must be translucent, rigid and stable, and should be easy to sterilize and insert in the mouth. surgical templates brings many advantages to the surgeon, but drawbacks like, the risk of bone overheating due to the obstruction of the cooling system and the existence of some instability, especially in fully edentulous
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patients, in which the template is only supported by the mucosa. He also pointed out that errors during template fabrication due to distortion of digital images and improper template positioning during the surgery may lead to lack of accuracy.
Ganz SD (2008) 21 did a detail study on the use of computerized tomography (CT) as a major diagnostic tool, making the surgical/prosthetic implant treatment planning and obtaining easier and more accurate outcome. He also explained the use of a CT scan, as pre-operative three-dimensional (3D) view tool of the surgical field available for treatment planning instead of the two-dimensional image seen in the conventional radiography and demonstrated the method of constructing and execution.
Hall EJ, Brenner DJ (2008) 18 conducted a survey to assess the risk of cancer from diagnotic radiology and found that the usage of computerised tomography has increased 12 to 20 times over two decades. Even the radiation doses vary widely and the real problem was not the amount of radiation the patient receives in one session, but the number of examinations done without any rationale. The authors concluded that the individual risks are considered small, but the increase in CT usage by health professionals has been the cause for real distress and may become a potential public care issue in the future.
Kelly Misch and Hom-Lay Wang (2008) 15 discussed the implant surgical complications under etiology and treatment topics and stated complications could rise from anatomy, treatment plan, procedure and iatrogenic human errors. On patient selection he pointed out that increase age 60-79, smoking, diabetes, head and neck radiation and postmenopausal estrogen therapy are strongly associated with failure rates.
He also emphasised on placing the implant in proper angulation in relationship with the corresponding arch and tooth to maintain the lingual, buccal cusp inclinations to avoid lingual perforations and avoidance of finger rest will reduce the angulation problem as the
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implant position can shift to the steadied hand. The implant location selection should allow 1-1.5 mm from adjacent tooth and 3-4 mm between adjacent implant to avoid bone loss and placing them 1-2 mm above nerve as an safety protocol and advocated, a flap less technique should be avoided in potential perforation areas were the bone is thin in buccal or lingual cortex to avoid haemorrhage. An immediate placement of implant should not considered as a contraindication in maxillary sinus lift procedure as they did not alter the outcome, except for secondary stage surgery and implant survival. They also listed the mechanical problems like the temperature and discussed the length and type of bone and advocated a 2500 rpm speed to decrease osseous damage and avoidance of wrong implant size and diameter selection can reduce the mandibular fracture in atropic ridges. The authors suggested that the lack of primary stability should be considered as failure in immediate and delayed procedure and the implant should be removed or replace with larger diameter.
Saad A Al-Harbi , Albert Y.T.Sun (2009) 4 did a study to evaluate implant placement accuracy using stereolithographic surgical template which the implant angulation and entry point was transferred by coordinate measure machine (CMM) which uses a laser probe. 40 implants were placed in 6 edentulous jaws in which the central axis of each treatment-planned implant was determined using the CMM, showed a mean mesio - distal angle deviation of 0.7 (+ or - 5.02) degree and bucco - lingual angle deviation of 0.46 ( + or - 4.43) degrees. The entrance point variation was 0.2 (+ or - 0.72) in which 85 % implants were with in < 1mm from the planned position, and a < 7 degree deviation on bucco lingual, mesio distal angulation in 88 % and 91% placed implants respectively.
Park et al (2009) 35 examined the outcome of guide height and its influence on guide surgery versus free hand placement. The guided surgery showed very less deviation at implant level, abutment level, apex and angle (p<.001) with the guide height ( 4, 6, 8mm)
16
showing less significance (p = .196), ( p= .418), ( p= .728) and (p=.075) respectively.
They also suggested reduction in height of guide can produce more accurate placement with out compromising the angulation.
Naina Talwar et al (2010) 45 stated that the implant supported prosthesis, requires determination of final prosthesis in treatment planning stage. This concept allows to predict the implant position during the diagnostic stage according to the planned definitive restoration. In prosthetically guided implantology, use of radiograph, surgical stent in conjunction with dental CT scan can also play an important role in the ideal
placement of implant in the determined position of the definitive restoration.
A radiographic stent is an appliance which is used to locate optimal site for implant placement in treatment planning. The radiographic stent with dental CT scan enables to identify the specific sites for prospective implant position and angulation.
U. S. Pal et al (2010) 24 demonstrated the accuracy and clinical precision of conventional surgical stent protocol for placing the dental implants in terms of position and diameter in a study comprised of 45 patients for whom 89 implants were placed at different sites. He used a stent which was fabricated with self-cure material after taking the primary impression of the patients and marking mesiodistal and buccolingual diameters on the cast and fabricated. Holes were drilled in the stent at the center point of the proposed implant site and filled with gutta percha. The stent was placed in the patient mouth and a panaromic radiograph was taken to evaluate the position of gutta percha.The possibility of displacement of stent during implant surgery was minimized by extension of the stent antero-posteriorly to cover enough area over the teeth/tooth present adjacent to edentulous area. In cases where no teeth are present, stabilization of stent was achieved by extending it over the unreflected areas like retromolar regions.This study results showed extreme accuracy of this conventional surgical stent to deliver an optimum
17
implant installation in terms of position and diameter and later function, at a very much reduced rate and time.
Claudine Wulfman et al (2010) 23 describes a simple duplicating procedure of denture, using poly vinyl silicone which can be used as template to plan and execute the placement of implant for mandibular implant-retained overdenture. This template acts as radiographic guide to validate or modify the implant planning by placing 2.0 mm twist drill to the long axis, on the lingual side. This radiographic guide allowed the visualization of the planned implant axis, prosthetic volume, emergence site, available prosthetic space for the attachment components, and mucosal thickness and make modifications. Fixation of 3.0mm metal tubes with internal diameter of 2.1mm allows the guide drill to be placed in the implant planned prosthetic axis position. Later, the guide can be converted into an occlusally adapted custom tray to make impression for complete mandibular implant-retained overdenture.
Hans-Joachin Nickening et al (2010) 38 did a comparison study for accuracy of implant placement using virtual planning and free hand method. The accuracy of axis was significantly more precise with the 3-D surgical guide (4.2_ (range, 0.0-10.0)) compared to the free-hand method performed by the maxillofacial surgeon (9.8_ (range, 3.7-17; p ¼ 0.000)) or by the prosthodontist (10.9° (range, 2.0-20; p ¼ 0.000)). The 3-D surgical guide template produced significantly smaller variation between the planned and the actual implant position at the apex of the implant. Based on evaluation of position and axis, the results showed that the accuracy of implant placement after virtual planning using cone-beam CT data and surgical templates were highly significant and accurate than freehand insertion.
Philip Worthington et al (2010) 25 formed protocols to use cone beam computerized tomography to accurately capture, display and provide visualization of 3-D maxillofacial
18
anatomy. Cone beam computerized tomography can be used to assess alveolar bone height, bone width, bone quality, pathosis, interarch space, maxillomandibular relationships and temporomandibular joints. They also suggested to take a small volume element (voxel) size (0.20 or 0.25 mm) and to adapt patient immobilization techniques during scanning. They also advocated to use 1mm slice thickness and a spacing of 1 0r 2 mm. They also quoted that the evolution in CBCT hardware and software has been responsible for the increase in the precise planning and placement of implants while minimizing the associated risks.
Raul Gonzalez, Florencio Monje (2011) 22 examined the accuracy of Cone beam
computerized tomography on assessment of bone density in healthy patients who were planed with Nobel guide software and subjected to implant placement with stereo lithographically created surgical guide. The emission of radiation in Cone Beam Computer Tomography, in the mean absorbed radiation was 12 mSV or 0.62 mGy which was 25% of the dose of conventional panoramic radiography and 40 - 50 times lesser than conventional CT. Additionally they added that CBCT allowed them to analyze its reliability to characterize bone density in the site of dental implants but concluded that needed further study.
Naina Talwar et al (2012) 1 did a study to the efficacy of a dual purpose (diagnostic and surgical) acrylic resin stent with gutta percha marker used in conjunction with 3D imaging in determination of the position and inclination of dental implants as compared to implant placement without the use of a stent. The gutta percha acrylic resin stent serves both as an imaging and surgical stent. It serves as a radiopaque indicator transposing the planned prosthetic angulation to a cross-sectional tomogram; later, the access hole was converted to osteotomy guide after the removal of gutta percha after calculating the difference between the radiographic bone trajectory and planned prosthetic trajectory, by
19
tracing them through the long axis of the radio opaque marker and demonstrated that a more accurate implant placement could be obtained with a acrylic resin stent and 3D imaging. The over all efficiency of 98.9% comparing 66.9% in control group was achieved by analyzing the parameters like distance from buccal and lingual cortical plates, inter implant distance and bucco lingual angulation of the implant to underlying alveolar bone.
Michael Patras et al (2012) 27 said that rehabilitations often required a significant amount of healing time in delayed loading protocols and advocated the usage of removable interim restorations during the transitional period. But for many patients he found that this treatment approach was not attractive due to the consequent impact of an interim removable prosthesis on psychology, phonetics and mastication. Patients with thin gingival biotype, needed extensive surgeries and in clinical cases where immediate loading is contraindicated, the clinician was forced to use a interim implant supported denture for a smoother transition into the fixed implant restorations.
Kathleen Manuela D’Souza, Meena Ajay Aras (2012) 31 compared 3 categories namely- nonlimiting, partially limiting, and completely limiting design surgical template for placement of implant and concluded that the completely limiting design was considered a far superior design concept. They complained that most clinicians still adopt the partially limiting design due to its cost-effectiveness and credibility in the field. The Completely limiting design restricts all the instruments used for the osteotomy for placement of implants in buccolingual and mesiodistal plane. Moreover, the addition of drill stops limits the depth of the preparation, and thus, allowing the implant placement for the prosthetic table. The he surgical guides are more restrictive and allows less of the decision-making and subsequent surgical execution intraoperatively. The completely limiting design surgical template are produced with two popular designs: cast-based
20
guided surgical guide and computer-assisted design and manufacturing (CAD/CAM) based surgical guide.
Manikandan Ramasamy et al (2013) 28 said that the optimal prosthodontic requirements could not be met with a well placed implant using conventionally made surgical guide as the results are often unpredictable, as the location and deviation of the implants may not be assessed. He also suggested that by usage of computed tomography, 3D implant planning software, image-guided template production techniques, and computer-aided surgery the planning and execution of surgical procedures produce a high success rate without causing iatrogenic damage and optimal use of available bone by diagnostic means.
Jun Kuo et al (2013) 29 said that, the implant can be better positioned using surgical stents but often the size of the grill guide channels, thickness and height of the stent limit the usage. He advocated a height of 5 mm, thickness of 2mm and use of assistant guide, the surgeons can precisely place an implant in its predetermined position and with the intended angulation with the guide additionally facilitating the fabrication of the dental prosthesis.
Mohammed Zaheer Kola et al (2015) 47 said that fulfilling the increased prosthetic demands needs highly accurate diagnosis, planning, and placement with the application of recent surgical reconstructive methods. Identification of the bony anatomy with respect to the teeth, prior to surgery, allows the clinician to place implants in areas where the implant bone interface can be maximized, and the prosthetic results can be optimized.
Computer-aided planning and image-guided surgery can be precisely executed, with optimal use of available bone, with CT scan and recommended a diagnostic means evidence-based research still needs to be conducted to evaluate the applications of the completely limiting design and its effect on the treatment outcome in oral implantology.
21
Pragya Pandey et al (2016) 49 described various methods of fabrication of surgical guide based on the following concepts: 1.Non limiting design - without any emphasis on the angulation of the drill. 2. Partially limiting design - only first drill used for osteotomy is directed using the surgical guide. 3. Completely Limiting Design - does not allow the operator to alter the guide settings. These guides are based on (a). Cast based surgical guide - in which periapical radiograph is modified using digital software to help in transposition of root structure on to the cast . (b).CAD-CAM based surgical guide - using stereolithography model to guide the osteotomy drills precisely.
MATERIALS & METHODS
22
ANGULATION POSITIONING DEVICE: A (FIG 1) (PATTENTED) (SRDC DENTAL IMPLANT SURGICAL POSITIONING GUIDE)
- A modified protractor, which has a groove and angulation guide sleeve, where in the protractor has a radial slot and 0° to 180° angle markings. (A1)
- The base portion of the protractor comprises of two metal arms extending in perpendicular direction, where the threaded bushes will be fitted. (A3)
- Threaded bushes are rigidly fitted to the metal arm portions of the protractor such that their axis is arranged parallel to the protractor’s base. (A4)
- The screw assembly comprises a threaded portion for engagement with the threads of the threaded bush and a head portion for fixing and removing the device. (A5) - The guide sleeve (A2) comprises a holder having cylindrical opening for the
passage of cylindrical locating pin (Angulation Guide Rod), has two diameters 6mm (A1a) and 7mm (A1b)
ANGULATION GUIDE METAL ROD: B (FIG 2)
- It is a straight metal rod divided into three parts according to the diameter:
- Parallel lines are drawn on the metal rod in all 4 directions to maintain the parallelism, throughout the procedure. (B1)
- The handle which is 12mm in diameter is used to hold the metal rod. (B2) - The guide sleeve compartment (B3) is available in two diameters:
5.8mm diameter for 6mm guide sleeve (B3a) with 5.5mm end diameter (B4a)
6.8mm diameter for 7mm guide sleeve (B3b) with 6.5mm end diameter (B4b)
23 GUIDE RING: C (FIG 3)
- These are stainless steel rings with a height of 5mm.
- With threads placed on the inner aspect, to engage the drill guides during implant placement. (C1)
- Available in two diameters
6mm outer diameter with 5.8mm inner diameter (C2a)
7mm outer diameter with 6.8mm inner diameter. (C2b)
Schematic diagram showing the engagement of angulation guide rod to the guide ring (FIG 4)
DRILL GUIDE: D (FIG 5)
- These tubes threaded on outer diameter to engage the guide ring and have a smooth surface inside to accommodate the drills. (D1)
- The drill guides are available in various diameters and height such as Height- 6mm,8mm and 10mm. (D2)
Diameter- 2.1mm, 3.6mm and 4.3mm (D3)
In our study we have used nobel select implant drills with diameters 2.0mm,3.5mm and 4.2mm, for which drill guides with inner diameters (2.1mm, 3.6mm and 4.3mm) were used accordingly.
24
ANGULATION POSITIONING DEVICE (SRDC-DISG) PATTENTED PENDING DESIGN NO: 201741044809
FIGURE 1 A1-Angulation from 0° to 180°.
A2-Guide sleeve.
A3-Metal arm portion of the protractor.
A-4Head portion of the screw assembly.
A5-Threaded bush fitted to the arm portion.
A1
A5 A4 A3
A2
A1a A1b 6mm 7mm
25 ANGULATION METAL ROD
B1a B1b FIGURE 2
B1-Parallel lines
B2-Handle
B3-Guide sleeve portion (B3a- 7mm, B3b- 6mm)
B4-Guide ring holder (B4a- 6.5mm, B4b- 5.5mm)
B 1 B 2
B 3 a
B 4 a
B 3 b
B 4 a
26
GUIDE RING
C2a (6mm) C2b (7mm) FIGURE 3
C1-Threads on the inner aspect of the guide sleeve SCHEMATIC DIAGRAM
FIGURE 4
Engagement of angulation guide rod to the guide ring with an inner diameter of 5.8mm - The outer diameter is 0.16mm + 0.16mm= 0.32mm
- The thread pitch in the inner aspect is 0.09mm +0.09mm= 0.18mm - The diameter of the angulation guide rod is 5.5mm
6mm
5.5mm 0.09m
m 0.16mm
6mm
C1
27 DRILL GUIDES (PATTENTED DESIGN NO: )
FIGURES 5 D1- Threads on the outer aspect of the guide ring
D2- Various length of the drill guides 6mm,8mm and 10mm
D3- Different diameters of the drill guides 2.1mm,3.6mm and 4.3mm
6mm 10mm D 1
2.1mm 3.6mm 4.3mm
8mm
D 2
28 METHODOLOGY:
IN-VITRO STUDY: -
i. Selection of alloplastic maxillary and mandibular model for in-vitro study ii. Duplication of the model.
iii. Pre-diagnostic imaging CT/CBCT to be done for determining anatomical structures relationship and planning of implant.
iv. Angulation transfer to the cast with the using Angulation positioning device.
v. Radiographic/ Surgical thermoplastic stent is fabrication.
vi. Radiographic stent evaluation using CT/CBCT.
vii. Dummy implant placement using surgical guide.
viii. A confirmatory CT/CBCT is taken to determine the angulation of the placed implant.
ix. Statistical evaluation.
29
METHODOLOGY
CASE STUDY: -
i. Selection of patient with partially edentulous area, with no systemic conditions.
ii. Upper and Lower impression of the patient is taken.
iii. Diagnostic CT/CBCT (sectional) scan taken.
iv. Fabrication of surgical guide stent.
v. Placement of implant with the fabricated surgical guide stent.
vi. Confirmatory CT/CBCT is taken to find out the placed implant angulation.
30 TABLE 1: MATERIALS
S.NO MATERIALS
BRAND, MANUFRACTURE 1. Alloplastic replica of partially edentulous
maxilla- Type 2, bone quality
Nobel biocare
2. Acrylic teeth used for replacement of edentulous area
Acry Rock
3. 1mm thickness, thermoplastic retainer Dentsply, Essix ACE Plastic
4. Diametric screws used in the stent Stainless steel, AISI-316 5. Dummy implant was of size 4.3mm× 13mm Nobel Replace Select,
Nobel biocare
31 TABLE 2: EQUIPMENTS
S.NO PROCEDURE INSTRUMENT
1. CT scan (model/patient) SIMENS SOMATOM
Definition Flash,256 slice dual stellar detector, Germany
2. CBCT scan (patient) (exposure- 90KV &8Ma)
PLANMECA
Software-Romexis Viewer Version 4.5.0.R
3. Radiographic imaging SIRONA
4. Thermoplastic stent fabrication DELTA LAB, Vaccum Forming Machine
32 IN VITRO STUDY
1. Selection of alloplastic model.
Alloplastic maxillary and mandibular models is selected for the study. Both the models had varied type of bone quality and various tooth missing. (FIG 6)
2. Duplication of model.
Tooth setting is done in the model, followed by impression using alginate. And cast is duplicated using dental stone. (FIG 7)
3. Pre-diagnostic scan for determination of anatomical structures and planning of implant angulation.
A pre-diagnostic CT/CBCT scan is taken to determine the relation to anatomical structures, planning of implant position and angulation. The base of the models is used as the ideal 180° horizontal vertex for angulation planning (FIG 8). The planned angulations are recorded.
4. Transferring of determined angulation to the cast.
Step 1-A horizontal line (crestal line) is drawn from the mesial to distal aspect of the edentulous area, to be replaced by implant. This determines the mesio-distal width available.
Step 2- Using the implant placement criteria, a equidistant point is marked on the horizontal line. From this point, a vertical line is drawn to the buccal and lingual side.
Step2 and step 3 will aid in the selection of implant diameter.
Step 3- Two parallel lines are drawn to the first vertical line. The two parallel denotes the outer diameter of the implant. The selected implant diameter is copied
33
to the model as two parallel vertical lines (V2,V3) (FIG 9) as either side of the first vertical line (V1).
Step 4- From the vertical line,(V1) line is drawn 5mm distally (or) mesially. The angulation positioning device is fixed on this line, at the selected implant length or at any point on the line. (FIG 10)
Step 5- The guide sleeve is fixed at 90° at the cast using the angulation guide rod through the guide sleeve. The lines drawn on the cast and the lines on the angulation guide rod is correlated, to the achieved position (i.e.) the lines drawn on the horizontal and vertical axis should be parallel and perpendicular to each other. (FIG 11)
Step 6-The guide sleeve is slided to planned angulation and fixed using threaded bush to the protractor. (FIG 12)
Step7- The guide ring is engaged to model using the angulation rod through the guide sleeve and fixed using wax (or) cryoacrylate wax. (FIG 13)
Step 8- Model is transferred to the lab for fabrication of stent (Radiographic/Surgical) (FIG 14) of 1.00mm thickness using ESSIX ACE PLASTIC sheet (FIG 15). The machine used for fabrication of the sheet is a THERMO VACCUM FORMING MACHINE (FIG16).
5. CT/CBCT scan.
The radiographic/surgical stent, is placed on the model and subjected to CT/CBCT scan,to assess the planned angulation of the guide ring. (FIG 17). The angulation achieved are recorded.
6. Implant placement.
The implants were placed according to the drill sequence provided by the manufacture using drill guides, adjusting it to reach the model.(FIG 18)
34 7. Confirmatory CT/CBCT.
After the placement of implants the model were subjected to CT/CBCT. The angulation of the implants were recorded. The results were compare and evaluated for the implant angulation and position, between pre-operatively, radiographic and post implant insertion. (FIG 19)
35
FIGURES
FIGURE 6 Fabricated model
FIGURE 7
Duplication of the model
36 FIGURE 8
Determination of angulation using CBCT
FIGURE 9 Drawn vertical lines
V2 V1 V3
37 FIGURE 10
Line marked for fixation of the angulation positioning device
FIGURE 11
The angulation guide rod and guide sleeve positioned at in 90°.
38 FIGURE 12
The device is fixed the determined angulation
FIGURE 13
Guide ring held in position with wax
39 FIGURE 14
Fabricated surgical guide on the model
FIGURE 15
Sheet used for fabricatin of the guide sleeve
40 FIGURE 16
Machine used for fabrication of stent
FIGURE 17
CBCT scan taken to determine the position of the guide ring
41 FIGURE 18
Drill guides reach upto the osteotomoy site
FIGURE 19
CBCT scan taken to determine the final position of implant placement
RESULTS
42
The predetermined, achieved measurements during radiographic and surgical stent preparation were evaluation for implant placement accuracy and angulation. The main parameters for the study was the placement of dental implant in the determined angulation.
ANGULATION DETERMINATION:
In alloplastic models 10 implants were placed the angulation determination was done with the help of CT/CBCT another radiograph was taken to determine the achieved angulation.
The mean percentage error was calculated statistically.
TABLE 1: Determined and Achieved angulations
Tooth number Determined Achieved Percent error
26 103.04 103 0.038
15 80 80 0
16 70.00 70 0
35 98.88 97.86 1.03
36 90 90 0
32 102.06 102.94 -0.086
36-I 96.47 96.40 0.072
34-I 110.02 110.65 -0.57
32-I 111.46 111.45 0
41-I 117.43 117.43 0
Average 97.94 97.97 0.048
43
TABLE 2: Mean, Standard Deviations of mean values of determined and achieved angulations and mean percentage difference in errors.
N Minimum Maximum Mean Std. Deviation Determined 10 70 117 97.94 14.606
Achieved 10 70 117 97.97 14.691
% Diff 10 -0.57 1.03 .0484 .39107
The difference in the angulation values among determined and achieved groups was analysed using students t test. There was no statistically significant difference in the mean angulation values suggesting that there is no difference in the angulations determined by angulation positioning guide.
44
Figure 20
Mean angulation values and mean percentage difference in errors values.
Figure 21
Distribution of percentage errors among all the samples
97.94 97.97
0.0484 0
20 40 60 80 100 120
Determined Acheived % Diff
Mean
0.038 0 0
1.03
0
-0.086
0.072
-0.57
0 0
-0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1 1.2
1 2 3 4 5 6 7 8 9 10
Percent error
45
REVERSE ANGULATIONS
DETERMINED ACHEIVED
D E T E R
63.43°
69.46°
70.02°
63.43°
69.45°
70.65°
46
DETERMINED ACHEIVED
103.04°
80.00°
70.00°
103°
80.00°
70.00°
47
DETERMINED ACHEIVED
102.06°
98.88°
102.94°
97.86°
48
DETERMINED ACHEIVED
90.00° 90.00°
49 CLINICAL CASE OF MISSING 36
DETERMINED- 86.81° ACHIEVED- 87 °
CLINICAL CASE OF MISSING 21
DETERMINED -121.61° ACHIEVED- 121.20°
DISCUSSION
50
Dental implants have become a predictable treatment option for restoring missing teeth. The purpose of tooth replacement with implants is to restore adequate function and esthetics without affecting adjacent hard and/or soft tissue structures. The factors responsible for success of dental implant placement depends on the bone height, bone width, angulation and surrounding anatomical structures. Early replacement decreases the volume of bone changes after tooth loss, with functional load of tooth.Selection of proper implant size is important as it hinders with the adjacent anatomical structures as well as prosthetic rehabilitation. A general guideline of 1.5mm of surgical error is maintained between the implant and any adjacent anatomical landmark 10.
The height of the available bone is calculated from the crest of the edentulous ridge to the opposing landmark such as the maxillary sinus or inferior alveolar nerve. The minimum of 10mm bone height is required for a long term implant survival. There should be a minimum of 2mm distance from the apex of the implant to the adjacent anatomical structure. The width of the available bone is measured between the facial and lingual plates at the crest of the desired implant site. A minimum of 1mm of bone on either side of the implant at the crest should be present. A study conoducted by Motoyoshi et al to assess the cortical bone thickness was carried out in 4 males (11 implants) and 28 females (76 implants) who ranged in age from 14.6 to 42.8 years. The success rate of the 87 implants was 87.4%. Cortical bone thickness was significantly greater in the success group (1.42 +/- 0.59 mm vs 0.97 +/- 0.31 mm, P = .015). In cadaveric maxilla and mandible study, the dentulous mandible showed buccal and lingual cortical measurements as 0.99 to 1.98 mm and 1.24 to 2.51 mm, respectively and the thinnest area in lower anterior region, and thickest in posterior mandible were assessed 11.
