A tomographic study of the mandibular condyle position in partially edentulous population.

BACKGROUND AND OBJECTIVES: The Influence of the loss of teeth on the condylar position and on temporomandibular joint (TMJ) dysfunction syndrome remains a c ontroversial issue. This study analyses the condylar position by means of a tomogram in partially dentate subjects which serves as a guide to predict which of the partially dentate statuses is prone to develop TMJ dysfunction syndrome in personnel without symptoms of the same. METHODOLOGY: Eighty personnel were enrolled in this study consisting of Kennedy's class I, II, III, IV and control to analyze the condylar position by means of a tomogram. In all the five groups TMJ sectional tomogram programmed in a panoramic radiographic machine (PLANMECA PM 2002 CC PROLINE) was taken with the subjects at maximal intercuspal position and rest position. Tomograms were evaluated using linear measurements of the anterior and posterior intra-articular joint spaces on the basis of drawings and tracings. RESULTS: The results of the study revealed a predominance of reduced posterior condylar space in Kennedy's class I and II. A disparity was seen between the maximum intercuspal position and rest position, where the posterior joint space was reduced in the rest position. CONCLUSION: Within the limitations of this study, it has been revealed that in Kennedy's classes I and II, for partially dentate personnel, a posterior displacement of the c ondyles was seen. This predisposition would suggest towards the necessity of restoring the missing dentition in order to maintain the har mony of the stomatognathic system.

Comparative Evaluation of Dimensional Accuracy and Tensile Strength of a Type IV Gypsum Using Microwave and Air Drying Methods.

To evaluate dimensional accuracy and tensile strength of a type IV gypsum product, at different time intervals, dried in air or a microwave oven. Eighty specimens prepared from a cylindrical mould were used for measuring tensile strength (group A). Twenty specimens from a master die mould were used for determining dimensional accuracy (group B). In group A, 40 specimens were dried in open air at room temperature (A1). The other 40 were removed after 30 min and air dried for 20 min. These were subjected to microwave oven drying for 5 min (A2). Ten specimens each were tested under diametral compression at each of the following time periods: 1, 2, 4 and 24 h after drying. In group B, ten specimens were dried in open air at room temperature (B1). Ten specimens were removed from the mould after 30 min and air dried for 20 min. These were then dried in a microwave oven for 5 min (B2). The data was statistically analyzed using students unpaired "t" test. At all time intervals, diametral tensile strength (DTS) values for specimens dried in microwave oven were significantly higher than for those dried in open air. There were no significant differences between the dimensional accuracy of the two groups. In this study, microwave oven drying had a positive effect on the DTS of a type IV gypsum and the microwave oven dried specimens were as accurate as the air dried specimens over the same time period.

To determine and compare the position of neutral zone in relation to crest of mandibular alveolar ridge with different duration of edentulousness: A clinico-radiographic study.

PURPOSE: The purpose of this study was to establish a relation between the crest of alveolar ridge and functionally obtained neutral zone and to determine the effect of duration of edentulousness on the location of neutral zone in relation to the crest of residual alveolar ridge. MATERIALS AND METHODS: The study included three groups: Group I-15 subjects edentulous for 0 months to 2 years; Group 2-15 subjects edentulous for 2-5 years; and Group 3-15 subjects edentulous for more than 5 years. Neutral zone recording was performed for each subject and the buccolingual relationship of the crest of the mandibular alveolar ridge and position of the neutral zone was examined. The results were analyzed by the Kruskal-Wallis H test and the Chi-square test. RESULTS: The results suggested that the location of the neutral zone varies from individual to individual depending on their musculature and that there is a significant relation to the duration of edentulousness. As edentulousness increases, there is more lingual positioning of the neutral zone at the molar region of both sides of the arch. At the premolar region, there is no change in position of the neutral zone; it remains constant as resorption of the alveolar ridge is directly under the buttress. In the anterior region, there is more labial positioning of the neutral zone as edentulousness increases. CONCLUSIONS: This technique proves itself to be an easy and inexpensive way to determine the relationship between the crest of alveolar ridge and neutral zone. Incorporating this technique into practice will be a great aid that can be exploited by the clinicians for functional and psychological comfort of the patients.

Assessment of Maxillary and Mandibular Bone Density in Controlled Type II Diabetes: A Computed Tomography Study.

This study was undertaken to compare the bone density in nondiabetic and controlled type II diabetes patients using spiral computed tomography. A group of 40 edentulous men, comprising of 20 nondiabetics and 20 controlled type II diabetics between the ages of 50-65 years, were enrolled in the study. Glycemic control of the diabetic patients was assessed by glycosylated hemoglobin level. The controlled diabetic group had an HbA1c level between 6.1-8%. A radiographic stent was prepared by using chemically cured resin. Bone densities at trabecular, buccal, and lingual cortical regions of maxillary and mandibular edentulous arches were measured by a tomography machine. Mean bone density measurements were recorded in Hounsfield units. The data thus obtained from 10 sites of maxillary and mandibular arches were tabulated and analyzed using SPSS statistical software. This study showed no significant changes in bone density between the controlled diabetic and nondiabetic subjects. Within the limitation of this study, it can be concluded that bone density does not seem to be affected in controlled type II diabetics.

The effect of 0.5% sodium hypochlorite and 2% glutaraldehyde spray disenfectants on irreversible hydrocolloid impression material.

Infection control has assumed prime importance in dentistry. It is a prime concern in prosthodontics as well, where impressions materials are most commonly used. Impression materials can act as a medium for cross infection. To prevent cross infection many products are being developed. Among them 0.5% Sodium hypochlorite and 2% Glutaraldehyde are considered effective. This study was done to asses the efficacy of 0.5% Sodium hypochlorite and 2% Glutaraldehyde on irreversible hydrocolloid impression material. The result of the study indicated that they are effective against both Gram positive and Gram negative organisms and their use is recommended.

Osseointegrated supported prosthesis and interdisciplinary approach for prosthodontic rehabilitation of a young patient with ectodermal dysplasia.

Anhidrotic ectodermal dysplasia is a triad of hypodontia or anodontia, hypotrichosis, and hypohydrosis, associated with other problems that result from the defective development of structures of ectodermal origin (Freire-Maia, Pinheiro (1988)). Early and extensive dental treatment is needed keeping in mind the effect on the craniofacial growth. Due to rapid growth of the jaws, the patients are rehabilitated using removable prostheses (Tarjan et al. (2005)). Hence for a young patient in this case report, the placement of endosseous osseointegrated implants was delayed till adulthood. Finally a definitive fixed tooth-supported and osseointegrated implant supported fixed partial denture therapy was used to rehabilitate the patient satisfactorily after she had completed her growth (Sweeney et al. (2005)). A review of the current literature relevant to several aspects of syndromic hypodontia, patient selection, and implant planning is discussed.

Effect of axial groove and resin luting cements on the retention of complete cast metal crowns.

BACKGROUND: The design of the tooth preparation and the cementing medium are important consid-erations in the retention of crowns and fixed partial dentures. The purpose of this invitro study was to determine the effect of axial groove on the retention of complete cast metal crowns using two resin luting cements. METHODS: Forty freshly extracted intact human molar teeth were prepared in their long axis to receive complete cast metal crowns. The specimens were randomly divided into two groups (one control and one study group). An axial groove of uniform size and shape was made on the prepared teeth under the study group. Axial surface area of prepared teeth specimens was measured. Complete cast metal crowns were fabricated for each specimen. Specimens of each group were divided into subgroups of 10 samples and were cemented with two resin luting cements, RelyX Unicem® and Calibra®, re-spectively. The cemented crowns were loaded in tension using a Universal Instron testing machine. The maximal tensile strength was recorded. Data were compared using the Mann-Whitney U test (α=0.05). RESULTS: NO SIGNIFICANT DIFFERENCES IN THE TENSILE STRESS VALUES WERE NOTED BETWEEN THE CONTROL (MEAN: 5.76±0.392 MPa) and study (mean: 5.93±0.751 MPa) groups cemented with RelyX Unicem. No significant differences in the tensile stress values were noted between the control (mean: 4.92±0.641 MPa) and study (mean: 5.15 ±0.478 MPa) groups cemented with Calibra. However, significant dif-ference in the tensile stress values was found between the two resin cements in the control and study groups. CONCLUSION: Axial groove placed in tooth preparations for resin bonded complete cast metal crowns had no statistically significant effect on retention. The use of (RelyX Unicem®) yielded greater retention values when compared to Calibra®.