Comparative evaulation of condylar guidance obtained by digital panoramic radiographic images with that of obtained during jaw relation and try-in using two different interocclusal record material in completely edentulous patients: an in vivo study

Background and rationale

In order to achieve a comfortable prosthesis that will last several years and maintain the patient's Temporomandibular joint health and intraoral components, proper interocclusal recording should be followed during the procedure.¹ In completely edentulous patients, the slope of articular eminence on a digital panoramic radiographic image will be traced, which will be utilised in the semi-adjustable articulator's programming.²

Mandibular movements can be mimicked with the help of a semi-adjustable articulator. Due to their ease of handling and programming, they are frequently used in prosthodontics.³ Mounting of the master casts on an articulator is very important step in treatment of complete edentulous patient.¹ In articulator programming, the device is modified to mimick the patient's temporomandibular joint structure and movement patterns of the patient. As a result, it acts as a patient when the patient is not present.³

Condylar guidance is described as mandibular guidance generated by the condyle and articular disc traversing the contour of the articular eminence-GTP-9.⁴ In the event that condylar guidance the mandibular movements are not accurately recorded, the occlusal interference will occur. The time it takes to adjust dentures might go up as a result. Therefore, it is crucial to accurately capture the maxillomandibular relationship.⁵

Condylar inclinations are provided by semi-adjustable articulators in two different ways: horizontally and laterally. Hanau's formula can be used to calculate the lateral condylar inclination from the horizontal condylar inclination (HCI), which determined with protrusive interocclusal records, or it can be done with individual lateral records.⁵

On semiadjustable articulators, The condylar guidance has been found to be unreliable when recorded and reproduced.⁵ There was a notable variation amongst the condylar guidance angle recorded successively by different practitioner, among multiple record materials, and amongst various articulator. This can be avoided by taking interocclusal records at various points in an edentulous subject, such as after teeth have been arranged or during jaw relation (Arrow point tracing). It is observed that records taken after teeth arrangement is much accurate. The values for the individual's condylar guidance are calculated using these records.³

Radiographs can also be used to measure condylar guidance. When compared to clinical methods, it is more reliable because it uses consistent bony landmarks and can be standardised. These pictures offer composite skeleton representations in the sagittal plane. In a semi-adjustable articulators, condylar guidance inclination will be set using outline of the eminence.³

Therefore, in the current research comparison of condylar guidance measurements will be made using records intraocclusally and digital orthopantomograph image in edentulous subject. Interocclusal recording medium should be capable of reproducing the details of the occlusal surface, as well as preserving the rigidity and accuracy of the materials for re-use more than once. For the purpose of keeping inter-occlusal records, there are several materials that can be used.¹ In this study we will also compare the precision and repeatability of two interocclusal recording materials, that is Reinforced wax and Polyvinylsiloxane (Jet bite) in determining the condylar inclination values in semi-adjustable articulators.

Objectives

Study design: Analytical observational study.

Study setting

The upcoming research work shall be done in Department of Prosthodontics Crown & Bridge at Sharad Pawar Dental college, Sawangi, Wardha.

Study participants

The study will be conducted on the patient reporting to the Department of Prosthodontics crown & bridge, with the chief complain of completely edentulous upper and lower archs and who are consider for complete denture prosthesis at Sharad Pawar dental college and hospital, Sawangi (Meghe), Wardha.

Inclusion criteria

Exclusion criteria

Evaulation of Condylar Guidance value by OPG

Orthopantomograph will be taken with the normal exposure and tracings will be done, Marking the Glenoid fossa (Superior curvature), Articular eminence (Inferior curvature) and the Frankfurt Horizontal Plane (FHP). The angle formed by joining the lines will be the horizontal condylar guidance angle, for that patient. The condylar guidance values on both right and left sides is recorded. This will be recorded for all the subject.

Conventional steps of complete denture

Preliminary Impressions will be taken with modelling compound and Impressions will be filled with dental plaster, a positive replica of primary impression known as preliminary cast. On which wax spacer and custom tray will be made. Using the low fusing impression compound, Border moulding will be done and Final impression will be taken by zinc oxided eugenol paste. This impression will also be poured with dental plaster and cast obtained will be the master cast. Temporary record base will be made on it along with the occlusal rims.

Determination of values of condylar guidance with the Interocclusal record material during Jaw relation stage

The jaw relation will be recorded using standard techniques. Face bow transfer will be completed and maxillary cast will be orient on the articulator with the centric relation record mandibular cast will be related to maxillary cast and mount on the articulator’s mandibular component. Tracers will be affixed to the rims of the maxilla and mandible. Subject will be seated in upright position and he/she will be trained for mandibular movements. Once the dentist is satisfy with the patients mandibular movements, tracer plate will be ready to document.

The patient will be asked to retrude the mandible in centric relation once a distinct arrow point tracing with a sharp apex has been made, and the interocclusal recorded using reinforced wax and polyvinyl siloxane (jet bite) will be taken. The rims will be held intraorally till interocclusal material is set. When the mandibular jaw is in the centric relation, the head of the condyle is positioned, anteriorly & superiorly within the mandibular fossa/glenoid fossa as it is possible. And protrusive interocclusal record will also be made by instructing patient to protrude 6mm of distance from the apex of the arrow and it will be marked. This will be programmed on hanu-articulator. Articulator programming simulate tmj anatomy and movements of the subject, thus it serves as subject in the absences of the subject. Horizontal condylar guidance adjustments will be freed by releasing the locknuts.

Determination of values of condylar guidance with the Interocclusal record material at try-in stage

Teeth arrangement will be done, will proceed for try-in procedure and interocclusal records will be made using two different interocclusal record material namely, Polyvinaly siloxane and Reinforced wax. As it is difficult to maintain jaw stability at 6mm protrusion position, we will make a Wax indentations prior which will help subject to maintain the desired protrusive jaw position. The articulator’s lower member will be moved forward by about 6 mm after the try-in procedure, and it will then be closed in that position. The trial dentures will then be placed on the articulator. The interaction of the upper and lower midlines, as well as the horizontal relationship between the lower and upper anterior teeth, will be closely scrutinised. The locknuts will be fixed in that position. After proper training of the patient, we will register interocclusal record using bite registration paste and reinforced wax, hold the records in the mouth till the material gets hard.

The programming of the articulator

On the articulator, the trial dentures will be put, and the interocclusal records will be used for programming. The maxillary cast will be constructed in two parts with a horizontal division method to evaluate the condylar guidance angulation. The condylar guidance values will be logged for both the interocclusal material reinforced wax and polyvinylsiloxane for each side, right and left of condyle.

The condylar guidance values succeeded in getting will be subjected to statistical analysis.

Variables and data measurements

Outcome: Expected outcome of the study is that it will help the clinicians to get knowledge about obtaining precise condylar inclination angle.

BIAS: Bias will be minimized as patients are randomly will be selected from the Outpatient Department of Department Prosthodontics Crown & Bridge, of Sharad Pawar Dental College and Hospital, Wardha.

Sample size calculation

Formula Using Mean difference

Where;

Z1-α/2 is level of significance at 5% i.e., 95%

Confidence interval = 1.96

Z1-β is the power of test = 90% = 1.28

Primary variable:

As per reference articles.

Minimum Total samples required = 7 per Group.

Minimum Total sample size is 14.

Statistical analysis

Statistical analysis will be done with the aid of Independent t-test., Analysis of variances (ANOVA) will be applied for analysis. The software that will be used in the analysis will be SPSS 27.0 version.

Dissemination

The scope of this study is to provide the dental practitioners with a method to effectively and precisely record condylar guidance, which won’t lead to maximum intercuspation interference while doing lower jaw movements. This will contribute to meet needs of the patient in accordance with the operation and durability of the denture in the oral cavity.

Study status: Study not yet started.

Limitations

Ethical considerations

Ethical approval received by Datta Meghe Institute of Higher Education and Research, Sawangi, Wardha (IEC ref no.-DMIHER (DU)/IEC/2023/849).