Rajiv Gandhi University of Health Science, Bangalore,

Karnataka

MDS PROSTHODONTICS INCLUDING CROWN AND BRIDGE WORK AND IMPLANTOLOGY

Synopsis for Registration of Dissertation

M R Ambedkar Dental College and Hospital

#1/36, Cline Road, Cooke Town

Bangalore, Karnataka- 560005

RAJIV GANDHI UNIVERSITY OF HEALTH SCIENCES

KARNATAKA, BANGALORE.

ANNEXURE II

SYNOPSIS FOR REGISTRATION OF DISSERTATION

1 / NAME OF THE CANDIDATE AND ADDRESS / Dr. ULLASH KUMAR
Dept. Of Prosthodontics, Including Crown and Bridge Work and Implantology
M. R. Ambedkar Dental College & Hospital
#1/36, Cline Road , Cooke Town
Bangalore-560005.
2 / NAME OF INSTITUTION / M R AMBEDKAR DENTAL COLLEGE & HOSPITAL
#1/36, Cline Road , Cooke Town
Bangalore-560005.
3 / COURSE OF STUDY AND SUBJECT / MDS PROSTHODONTICS, INCLUDING CROWN AND BRIDGE WORK AND IMPLANTOLOGY
4 / DATE OF ADMISSION / 30/05/2012
5 / TITLE OF THE TOPIC:
“COMPARATIVE EVALUATION OF DIRECT BONE MAPPING WITH CONE BEAM COMPUTED TOMOGRAPHY, ORTHOPANTOMOGRAPHY AND RIDGE MAPPING AS PRE-SURGICAL PLANNING FOR PLACEMENT OF IMPLANTS ON A CADAVERIC MANDIBLE : AN IN VITRO STUDY.”
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8. / BRIEF RESUME OF WORK :
NEED FOR STUDY :
Special care is necessary to avoid invading important structures during implant placement when pre surgical planning is made based on radiographs. However, none of these type of radiography represents a perfect modality. The purpose of this study is to determine the reliability of presurgical planning based on the use of two type of radiographic image (Orthopantomography [OPG] and cone-beam computed tomography [CBCT]) and ridge mapping to place implants and to quantify differences in measurements between radiographic images and real specimens.1
REVIEW OF LITERATURE
A study was done to assess the accuracy of ridge mapping in planning implant therapy for anterior maxillary region. The aim of this study was to assess the accuracy of ridge-mapping, using calipers in determining bony ridge widths in the anterior maxilla prior to dental implant surgery. A modified surgical stent was designed to locate the beaks of ridge-mapping calipers at the same points on the jaw before and after mucoperiosteal flap reflection. Eleven subjects were included in the study. Measurements were made at 25 implant sites 50 ‘pre-operative’ and 50 ‘intra operative’ at 3mm and 6 mm distances from the crest of the ridge. There was a statistically significant measurement difference between pre-operative and intra-operative measurements. Based on pre operative measurements, clinical judgements were made as to whether supplementary procedures such as guided bone regeneration would be required. Unanticipated supplementary procedures were required at ten implant sites. The findings indicate that Ridge-mapping alone is insufficient to accurately predict the bone available for implantation in the anterior maxilla. It is suggested that ridge-mapping may provide reliable information about bone levels when the labial aspect of the anterior ridge is markedly concave.2
A study was done to compare Linear tomography and Direct ridge mapping for the determination of edentulous ridge dimensions in human cadavers for which one site in the posterior mandible was selected for evaluation in each of five cadaver heads. Vaccum formed stents made from the model of cadaver ridges were used to identify three sets of measurement points for each specimen: coronal (intersection of coronal and middle third of ridge), middle (intersection of middle and apical third), and apical (base of the vestibule). The imaging stent contained 2 mm metal balls at each point, while the Ridge Mapping stent had holes drilled at the corresponding sites and measured with calipers. The results indicated that there were no significant differences between Linear Tomography and Ridge Mapping for ridge width measurements. Thus, the study concluded saying neither Linear tomography (LT) nor Ridge mapping (RM) proved to be completely accurate in determining ridge width in the posterior mandible when compared to direct measurements.3
A study was done to compare ridge-mapping measurement before surgical flap reflection and measurement using images from cone beam computerized tomography (CBCT) to direct caliper measurement following surgical exposure of the bone for which sixteen subjects with 25 sites for planned implant placement were recruited. An acrylic stent was fabricated for each subject which provided three buccal/lingual pairs of consistent measurement points for each implant site located 4, 7, 10 mm from the summit of the alveolar soft tissue. The results indicated that Cone Beam Computed Tomography (CBCT) image measurements provided lower level of agreement than ridge mapping measurements because of the more frequent and larger magnitudes of deviations compared to direct caliper measurements. According to the results obtained it was concluded that ridge mapping provides measurements of the bucco-lingual ridge width consistent with those obtained by direct caliper measurement following surgical exposure of the bone. As applied in this study, Cone Beam Computed Tomography (CBCT) was less consistent compared to direct caliper measurements and did not provide any additional, significant diagnostic information.4
A study was done to measure the accuracy of linear measurement provided by cone beam computed tomography to assess bone quantity in human cadavers in the posterior maxillary region for placement of implants using an image intensifier tube and television (TV) chain as an X-ray detector. Fourteen measurements were taken in three dry maxillae. On every anatomical site, three markers were placed on the bony crest to define a plane. Dry maxillae were submitted to Cone Beam Computed Tomography (CBCT) imaging examination. The maxillae were then sawn according to previously defined planes, and bone height and width were assessed using a caliper. The same measurements were taken on the images. The results demonstrated no difference between real measurement and image measurements. The study concluded saying although cadaver bone density may not correspond to the density of vital bone, this in vitro study indicates that Cone Beam Computed Tomography (CBCT) images are reliable to define the bone volume of the posterior maxilla for the purpose of planning the implant axis.5
A study was done to determine the reliability of presurgical planning based on the use of two types of radiographic image methods namely panoramic radiography and cone beam computed tomography to place implants and to quantify differences in measurements between radiographic images and real specimens, for which ten fresh cadavers without posterior teeth were used and two types of measurement errors of evaluated:1)the presurgical measurement error, defined as that between the presurgical and post surgical measurements in each modality of radiographic analysis, and 2) the measurement error between post surgical radiography and the real specimens. The results indicated that the mean presurgical measurement error was significantly smaller for Cone Beam Computed Tomography (CBCT) than for Digital Panoramic Radiography (DPR) in the maxillary region, whereas it did not differ significantly between the two imaging modalities in the mandibular region. The mean measurement error between radiography and real specimens were significantly smaller for Cone Beam Computed Tomography (CBCT) than for Digital Panoramic Radiography (DPR) in the maxillary region, but did not differ significantly in the mandibular region.1
OBJECTIVES OF THE STUDY:
·  To compare the accuracy of Cone Beam Computed Tomography (CBCT) and Orthopantomography (OPG) with respect to bone height measurement.
·  To compare the accuracy of Cone Beam Computed Tomography (CBCT) and Direct Ridge Mapping (RM) with respect to bone width measurement.
MATERIALS AND METHODS:
For this study thirty cadaveric mandibles will be used. The soft tissue will be simulated using VINYL POLYSILOXANE impression material (EXAFLEX). For each specimen, a single posterior implant site will be identified and a line drawn perpendicular to the occlusal plane. Points at an interval of 2mm at 4mm, 6mm and 8mm from the crest of the ridge will be marked along the line on the buccal and lingual aspects of the ridge.
A stent will be fabricated using clear self cure acrylic for each specimen. A 2mm metal ball will be attached in the radiographic stent at the crest of the ridge, and GUTTA PERCHA points will be attached at an interval of 2mm at 4mm, 6mm and 8mm from the crest of the ridge. This stent will then be used for Cone Beam Computed Tomography (CBCT), Orthopantomography (OPG) and caliper measurements.
The mandible will be immobilized with the median sagittal plane perpendicular to the horizontal plane as per the manufacturer instructions. Images will be acquired using CBCT. From volumetric primary data obtained, using the CBCT scan by means of what is called a primary reconstruction, axial images are obtained. They will then be transferred to a planning software program (DICOM) that can provide reformatted slices passing through planes previously defined on the dry mandible.
For each section, two parameters will be recorded: crest height and width, which are important data for preoperative planning. The height of the bone was defined as the distance between the mental foramen to the crest of the alveolar ridge. The width was defined as the distance between the lingual and the buccal plates measured on a line perpendicular to the height.
ORTHOPANTOMOGRAPHY.
The mandible will be immobilized with the mid sagittal plane perpendicular to the horizontal plane as per the manufacturer instructions. Images will be acquired using OPG machine. A 2mm metal ball will be attached in the radiographic stent at the crest of the ridge as a reference point. The height will then be calculated from the crest of the ridge to the mental foramen using GROSSMAN’S FORMULAE:
X1 Y1
------= ------
X2 Y2
Where X1: Actual height from the crest of the ridge to the mental foramen
X2: Radiographic height from the crest of the ridge to the mental foramen
Y1: Actual diameter of the metal ball
Y2: Radiographic diameter of the metal ball
RIDGE MAPPING PROCEDURES.
The ridge width of the specimen will be measured using a ridge mapping caliper. Width readings will be made at intervals of 4mm, 6mm, and 8 mm markings on the acrylic guide to align the caliper. For each reading, the examiner will insert the caliper beaks into the appropriate alignment holes, squeeze the caliper handles until bone is contacted and record the measurements.
DIRECT MEASUREMENTS.
The stent made up of clear self cure acrylic along with the soft tissue (vinyl polysiloxane) will be removed from the cadaveric mandible. An independent examiner who will be familiar with Ridge mapping, Orthopantomography and Cone Beam Computed Tomography and has not participated in the previous measurements will then use a digital vernier caliper to measure the alveolar ridge width at markings made earlier.
SOURCE OF DATA:
The cadaveric mandibles will be procured from B.R. Ambedkar Medical College and the data will be obtained by calculating the bone height and width from CBCT, orthopantomography, ridge mapping and direct bone measurements on thirty cadarveric mandibles. Data collected will then be analyzed statistically.
METHOD OF COLLECTION OF DATA:
Data will be obtained by using DICOM software for CBCT, measuring from OPG, ridge mapping by calipers and direct bone mapping by vernier calipers.
DOES THE STUDY REQUIRE ANY INVESTIGATIONS TO BE CONDUCTED ON PATIENTS ON OR OTHER HUMANS OR ANIMALS? IF SO, PLEASE DESCRIBE BRIEFLY.
No
HAS ETHICAL CLEARANCE BEEN OBTAINED FROM YOUR INSTITUTION IN CASE OF 7.3?
Not applicable
REFERENCES:
1.  Kyung-S Hu, Da-Yae Choi. Reliability of two different presurgical preparation methods for implant dentistry based on panoramic radiography and cone-beam computed tomography in cadavers. J Periodontal Implant Sci 2012; 42:39-44.
2.  Allen F, Smith DG. An assessment of the accuracy of ridge mapping in planning implant therapy for the anterior maxilla. Clin Oral Impl Res2000: 11: 34-38
3.  Perez LA, Sharon L. Comparision of linear tomography of linear tomography and direct ridge mapping for the determination of edentulous ridge dimensions in human cadavers .Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2005;99:748-54
4.  Chen LC, Tord L. Comparision of Different Methods of Assessing Alveolar Ridge Dimensions Prior to Dental Implant Placement. J Peridontol 2008; 79:401-405
5.  Goulet SV. Accuracy of linear measurement provided by cone beam computed tomography to asses bone quantity in the posterior maxilla: A human cadaver study. DOI 10.1111/j.1708-8208.2008.00083.x
9 / SIGNATURE OF THE
CANDIDATE
10 / REMARKS OF GUIDE
11 / NAME AND DESIGNATION OF GUIDE / Dr. ZUBEDA BEGUM
PROFESSOR, DEPARTMENT OF PROSTHODONTICS
11.1 / SIGNATURE
11.2 / NAME AND DESIGNATION OF THE CO- GUIDE
11.3 / SIGNATURE
11.4 / HEAD OF THE DEPARTMENT / Dr. AMARNATH G S
PROFESSOR & HEAD OF DEPARTMENT, DEPARTMENT OF PROSTHODONTICS.
11.5 / SIGNATURE
11.6 / REMARKS OF THE PRINCIPAL
11.7 / SIGNATURE