Modified protrusive wax record in recording condylar path angle and ethnic variations.

Background: The Condylar Path Angle (CPA) is an important measurement that is used to program articulators used in dental treatment. The purpose of the current study was to investigate the CPA in Malay subjects, to compare the measurements with average values, 25˚-35˚ Camper's (based on Caucasian studies), and to compare the right and left CPAs. Methods: Thirty subjects aged 21-23 years were recruited. A wash technique impression was made, casts were poured, and face-bow transfers were taken. The casts were mounted to their centric position on a semi-adjustable articulator. Protrusive guides were constructed to allow the mandible to be protruded for 5 mm, and then the angles were measured using the protrusive record method. Results: The right CPA was within the normal range for 43% (13/30) of participants and out of the normal range for 57% (17/30). The left CPA was within the normal range for 33% (10/30) of participants and out of the normal range for 67% (19/30). There was no statistically significant difference between the left and right CPAs (p = 0.72), but there was a strong linear relationship between left and right CPAs (p = 0.001). Conclusions: Results of the current study indicated Malay subjects had measurable variations in the CPA, suggesting this population has an ethnic variation in the CPA. Relevance for patients: To improve the quality of patient care, the CPA should be considered when constructing fixed/removable prostheses that use semi-adjustable articulators, and clinicians should not rely on the set average values that are pre-set on articulators.

Effect of cavity preparation on the flexural strengths of acrylic resin repairs

OBJECTIVE: To investigate the effect of cavity preparation on the flexural strength of heat-curing denture resin when repaired with an auto-curing resin. MATERIAL AND METHODS: Ninety-six rectangular specimens (64x10x2.5 mm) prepared from heat-curing denture base resin (Meliodent) were randomly divided into four groups before repair. One group was left intact as control. Each repair specimen was sectioned into two; one group was repaired using the conventional repair method (Group 1). Two groups had an additional transverse cavity (2x3.5x21.5 mm) prepared prior to the repair; one repaired with (Group 2) and one without glass-fiber reinforcement (Group 3). A three-point flexural bending test according to the ISO 1567:1999 specification8 for denture base polymers was carried out on all groups after 1, 7 and 30 days of water immersion. Statistical analysis was carried out using two-way ANOVA, Kruskal Wallis and post-hoc Mann Whitney tests. RESULTS: The highest flexural strength was observed in the control group. Control and conventional repairs group (Group 1) showed reduction in the flexural strength 30 days after water immersion. No significant change in the strength was observed for Groups 2 and 3 where the repair joints were similarly prepared with additional transverse cavity. CONCLUSION: Repaired specimens showed lower flexural strength values than intact heat-curing resin. Cavity preparation had no significant effect on the flexural strength of repair with water immersion.

Effect of cavity preparation on the flexural strengths of acrylic resin repairs.

OBJECTIVE: To investigate the effect of cavity preparation on the flexural strength of heat-curing denture resin when repaired with an auto-curing resin. MATERIAL AND METHODS: Ninety-six rectangular specimens (64 x 10 x 2.5 mm) prepared from heat-curing denture base resin (Meliodent) were randomly divided into four groups before repair. One group was left intact as control. Each repair specimen was sectioned into two; one group was repaired using the conventional repair method (Group 1). Two groups had an additional transverse cavity (2 x 3.5 x 21.5 mm) prepared prior to the repair; one repaired with (Group 2) and one without glass-fiber reinforcement (Group 3). A three-point flexural bending test according to the ISO 1567:1999 specification 8 for denture base polymers was carried out on all groups after 1, 7 and 30 days of water immersion. Statistical analysis was carried out using two-way ANOVA, Kruskal Wallis and post-hoc Mann Whitney tests. RESULTS: The highest flexural strength was observed in the control group. Control and conventional repairs group (Group 1) showed reduction in the flexural strength 30 days after water immersion. No significant change in the strength was observed for Groups 2 and 3 where the repair joints were similarly prepared with additional transverse cavity. CONCLUSION: Repaired specimens showed lower flexural strength values than intact heat-curing resin. Cavity preparation had no significant effect on the flexural strength of repair with water immersion.