Comparative Evaluation of Lateral Condylar Guidance Angle Measured Using Hanau’s Formula & Lateral Interocclusal Records

BACKGROUND The goal of registering condylar guidance is to program the articulator for simulating the patient’s condylar movements as accurately as possible to save chairside time involved in adjusting the occlusal interferences at the time of fit in. The use of Hanau’s formula (L = H / 8 +12) was advocated by Sir Rudolph Hanau in 1930 which he used to calculate lateral condylar guidance (LCG) for adjusting his articulators. But due to the ease of application, the formula is widely used by dentists till date. Jack Stern, Hanau's longterm partner, confided in 1960 that the 'Formula' was never considered to be precise, after 10 years of study (1920 - 1930). Rather it was a point of approximation. There is a lack of uniformity in the literature regarding average condylar inclinations and its comparison to the Hanau formula, therefore a study was undertaken to evaluate and compare the 2 methods used to determine the lateral condylar guidance. METHODS 24 completely dentulous participants were included in the study. Two methods were used to obtain the lateral condylar guidance, the first method was obtaining the calculated lateral condylar guidance using the hanau’s formula and the second was obtaining the measured lateral condylar guidance using the interocclusal records. Impressions of each participant were made. Protrusive and lateral records were made using interocclusal recording medium (MAARC® Perfect Bite Registration). After completion of facebow transfer, programming of the articulator was done using protrusive record and the horizontal condylar guidance was recorded. The calculated lateral condylar guidance was recorded using the Hanau’s formula & the measured condylar guidance was recorded using right and left lateral records. Both the values obtained were evaluated and compared. RESULTS Mean LCG values obtained using Hanau’s formula was 16 degrees for the left side (SD - 1.404) and for the right side it was 16.17 degrees. (SD - 1.694). Mean LCG values obtained using lateral interocclusal records were 20 degrees for the left side (SD - 6.691) and 20.08 degrees (SD - 4.926) for the right side.There was a statistically significant difference between lateral condylar guidance records obtained using Hanau’s formula and lateral interocclusal records. CONCLUSIONS Application of Hanau formula is helpful to estimate Bennett angle. No doubt the formula is easy to apply and less cumbersome, but when we are working on high precision demanding cases we should try and find better options to record LCG. Making a lateral interocclusal record and then programming the articulator is a more reliable method. KEY WORDS Hanau’s Formula, Bennet Angle, Condylar Guidance, Articulators, Interocclusal Records, Lateral Condylar Guidance

Expression of Substance P, Calcitonin Gene-Related Peptide and Vascular Endothelial Growth Factor in Human Dental Pulp Under Different Clinical Stimuli

Background To quantify the expression of SP, CGRP, and VEGF in human dental pulps as a response to occlusal interferences, moderate orthodontic forces, and occlusal interferences plus moderate orthodontic forces simultaneously.Methods Forty human dental pulp samples were collected from healthy premolars indicated for extraction for orthodontic reasons. The teeth were divided into four groups with 10 samples each: Healthy pulp control group, occlusal interference group, moderate orthodontic forces group; and occlusal interferences plus moderate orthodontic forces group. Stimuli were applied for 24 h before tooth extraction in all experimental groups. All samples were processed, and SP, CGRP, and VEGF were measured by radioimmunoassay. The ANOVA test was performed to establish significant differences between groups and Tukey’s HSD post hoc comparisons were also performed.Results The highest increase in SP, CGRP, and VEGF expressions was found in the occlusal trauma plus orthodontic forces group, followed by the moderate orthodontic forces, the occlusal interferences and the control groups, with statistically significant differences between all groups (ANOVA p<0.001) and post-hoc comparisons (Tukey HSD p<0.001).Conclusion SP, CGRP, and VEGF expressions significantly increase in human dental pulps when stimulated by occlusal interferences combined with moderate orthodontic forces, as compared with when these two stimuli are applied independently. Peptides expression is directly proportional to the magnitude of the stimulus.Name of the registry: Importance of Neurogenic Inflammation in the Angiogenic Response of the Dental Pulp as a Defensive ResponseTrial registration number: NCT03804034Date of registration: 01/15/2019 Retrospectively registeredURL of trial registry record: https://clinicaltrials.gov/ct2/show/NCT03804034?term=NCT03804034&draw=2&rank=1

ORAL REHABILITATION BY TWIN STAGE TECHNIQUE IN A CASE OF AMELOGENESIS IMPERFECTA

Amelogenesis Imperfecta (AI) is a diverse collection of inherited diseases that exhibit quantitative or qualitative tooth enamel defects in the absence of systemic manifestations. It is necessary to diagnose the case and provide durable functional and aesthetic management of these patients, as the unaesthetic appearance has a definite negative psychological impact. This clinical report describes the use of the Hobo twin-stage procedure for rehabilitation of a patient with amelogenesis imperfecta and reduced vertical dimension of occlusion. The treatment plan was executed keeping in mind not only the severely damaged dentition but also treating the whole stomatognathic system. Utmost care was taken to achieve harmonious occlusion with no possible occlusal interferences which would otherwise initiate the habit of bruxism and thereby cause wear of the prosthesis. KEY WORDS : Amelogenesis Imperfecta , Hobo twin-stage procedure , harmonious occlusion .

Management of skeletal Class III with facial asymmetry using skeletal anchorage: 4-year follow-up

ABSTRACT Introduction: Skeletal Class III malocclusion with asymmetry is one of the most difficult problems to correct in orthodontics. A functional shift of the mandible in growing patients may occur accompanying a Class III, due to constricted maxillary arch and occlusal interferences. Studies have indicated that posterior unilateral crossbite develops early and has a low rate of spontaneous correction. It may further lead to development of mandibular and facial asymmetry by growth and displacement of mandible if left untreated in growing patients. Objective: This article reports the clinical case of a thirteen-year-old female patient in CVMI transition stage that had maxillary hypoplasia with a developing facial asymmetry. Results: The case was successfully managed with bone-anchored facemask therapy and with elimination of occlusal interferences with guided occlusion. Reverse twin block in the retention phase maintained the results achieved. Conclusion: A four-year follow-up evaluation revealed successful maintenance of the treatment results.

Association between preferred chewing side and dynamic occlusal parameters

Objectives Evaluation of dynamic occlusal parameters can help dentists to understand the association of occlusion with the preferred chewing side (PCS) and enable optimal restoration of masticatory efficiency. This study evaluated the association between PCS and dynamic occlusal parameters. Methods One hundred participants (50 each, right and left PCS) were included in this study. PCS was determined by the visual spot-checking method, and occlusal analysis was conducted by T Scan. Occlusal parameters evaluated included initial contact, center of force, tooth contact area, occlusal interferences, and occlusal time. Data were assessed by chi-squared test and eta correlation coefficient. Results Initial contact towards the PCS was observed in 68% and 70% of right and left unilateral chewers, respectively. Likewise, center of force towards the PCS was present in 72% and 66% of right and left unilateral chewers, respectively. A larger area of tooth contact was predominant towards the PCS in 70% and 72% of right and left unilateral chewers, respectively. Chi-squared analysis showed a strong positive correlation between PCS and occlusal parameters at maximum intercuspation. Eta correlation coefficients between PCS and occlusal interferences, as well as centric and eccentric occlusion, revealed negligible associations. Conclusion Dynamic occlusal parameters may be associated with PCS.