ABSTRACT
BACKGROUND: In cement-retained implant-supported restoration it is important to gain adequate retention of definitive restoration as well as retrievability of prosthesis. The surface of the abutment, alloy of the restoration and the type of cement used influences the retention of the restoration. There is a need to analyze the influence of surface modifications of abutments on the retentive capabilities of provisional implant cements. PURPOSE OF STUDY: To compare the effect of implant abutment surface modifications on retention of implant-supported restoration cemented with polymer based cement. MATERIALS AND METHOD: Thirty solid titanium implant abutments (ADIN), 8mm height, were divided into 3 groups. Ten abutments with retentive grooves (Group I) as supplied by the manufacturer, Ten abutments milled to 20 taper circumferentially (Group II), and Ten abutments milled and air-abraded with 110 µm aluminum oxide (Group III) were used in this study. Ni-Cr coping were casted for each abutment and polymer based cement was used to secure them to the respective abutments. Using a universal testing machine at a crosshead speed of 0.5 cm/minute, tensile bond strength was recorded (N). RESULTS: Mean tensile bond strength of Group I, II and III were found to be 408.3, 159.9 and 743.8 Newton respectively. The values were statistically different from each other (p<0.001). CONCLUSION: Abutments with milled and sandblasted surface provide the highest retention followed by abutments with retentive grooves and then by abutments with milled surface when cast copings were cemented to implant abutments with polymer based cement. CLINICAL IMPLICATIONS: Retention of restoration depends on the surface of the abutment as well as the luting agents used. Incorporation of retentive grooves or particle abrasion can enhance retention especially in situation of short clinical crown.
ABSTRACT
AIM: To investigate the pulp chamber penetration of bleaching agent in intact teeth and teeth following restorative procedure. METHODOLOGY: Sixty extracted human incisors were selected and divided into 6 Groups. Four Groups were restored with hybrid composite resin and resin modified glass ionomer cement respectively, while 2 Groups were left intact. The Groups were then immersed in the treatment agents for 60 mins at 37°C. The optical density of the resultant blue solution obtained by adding leucocrystal violet and horseradish peroxidise to the acetate buffer solution present in the pulp chamber was measured spectrophotometrically and the data thus obtained was statistically analysed using ANOVA and paired t-test. RESULTS: The amount of pulpal peroxide penetration in restored teeth was significantly higher than intact teeth (p< 0.001). the control Group showed no peroxide penetration. Groups restored with resin modified glass ionomer cement showed higher pulpal peroxide levels than Groups restored with hybrid composites, though the difference was not statistically significant (p = 0.52). CONCLUSION: Peroxide readily penetrates into the pulp through intact and restored teeth, with restored teeth showing higher pulpal peroxide levels than intact teeth. Teeth restored with resin modified glass ionomer cement showed higher pulpal peroxide level than teeth restored with composite resins.
