Standards of teeth preparations for anterior resin bonded all-ceramic crowns in private dental practice in Jordan

OBJECTIVES: To investigate if general dental practitioners (GDPs) in private practice in Jordan follow universal guidelines for preparation of anterior teeth for resin bonded all-ceramic crowns (RBCs). MATERIAL AND METHODS: A sample (n=100) of laboratory models containing 208 tooth preparations for IPS Empress and In Ceram, featuring work from different GDPs, was obtained from 8 commercial dental laboratories. Aspects of preparations were quantified and compared with accepted criteria defined following a review of the literature and recommendations of the manufactures' guidelines. RESULTS: Subgingival margins on the buccal aspect were noticed in 36% of the preparations, 54% demonstrated overpreparation with a tendency to overprepare the teeth on the mesiodistal plane more than buccolingual plane. Twenty percent of samples presented a shoulder finish line while a chamfer margin design was noticed in 39%. Twenty-nine percent and 12% of samples had either a feathered or no clear margin design respectively. Incisal underpreparation was observed in 18% of dies of each type. Only 17% of all preparations were found to follow the recommended anatomical labial preparations while 29% of the RBC preparations were found to have the recommended axial convergence angle. In total, 43% of preparations were found to have the recommended depth of the finish line. CONCLUSIONS: It was found that relevant guidelines for RBC preparations were not being fully adhered to in private practice in Jordan

Standards of teeth preparations for anterior resin bonded all-ceramic crowns in private dental practice in Jordan

OBJECTIVES: To investigate if general dental practitioners (GDPs) in private practice in Jordan follow universal guidelines for preparation of anterior teeth for resin bonded all-ceramic crowns (RBCs). MATERIAL AND METHODS: A sample (n=100) of laboratory models containing 208 tooth preparations for IPS Empress and In Ceram, featuring work from different GDPs, was obtained from 8 commercial dental laboratories. Aspects of preparations were quantified and compared with accepted criteria defined following a review of the literature and recommendations of the manufactures' guidelines. RESULTS: Subgingival margins on the buccal aspect were noticed in 36% of the preparations, 54% demonstrated overpreparation with a tendency to overprepare the teeth on the mesiodistal plane more than buccolingual plane. Twenty percent of samples presented a shoulder finish line while a chamfer margin design was noticed in 39%. Twenty-nine percent and 12% of samples had either a feathered or no clear margin design respectively. Incisal underpreparation was observed in 18% of dies of each type. Only 17% of all preparations were found to follow the recommended anatomical labial preparations while 29% of the RBC preparations were found to have the recommended axial convergence angle. In total, 43% of preparations were found to have the recommended depth of the finish line. CONCLUSIONS: It was found that relevant guidelines for RBC preparations were not being fully adhered to in private practice in Jordan

Heat Generation on Implant Surface During Abutment Preparation at Different Elapsed Time Intervals

PURPOSE The purpose of this study was to evaluate heat generation at the implant surface caused by abutment preparation using a diamond bur in a high-speed dental turbine in vitro at 2 different water-coolant temperatures. MATERIALS AND METHODS Thirty-two titanium-alloy abutments were connected to a titanium-alloy implant embedded in an acrylic resin placed within a water bath at a controlled temperature of 37°C. The specimens were equally distributed into 2 groups (16 each). Group 1: the temperature was maintained at 20 ± 1°C; and group 2: the temperature was maintained at 32 ± 1°C. Each abutment was prepared in the axial plane for 1 minute and in the occlusal plane for 1 minute. The temperature of the heat generated from abutment preparation was recorded and measured at 3 distinct time intervals. RESULTS Water-coolant temperature (20°C vs 32°C) had a statistically significant effect on the implant's temperature change during preparation of the abutment (P < 0.0001). CONCLUSION The use of water-coolant temperature of 20 ± 1°C during preparation of the implant abutment decreased the temperature recorded at the implant surface to 34.46°C, whereas the coolant temperature of 32 ± 1°C increased the implant surface temperature to 40.94°C

Adhesion of cast metal alloy and lithium disilicate copings luted to different core build-up materials with self-adhesive resin cement

This study evaluated the shear bond strength of two coping materials (non-nickel chrome-based cast alloy and lithium disilicate ceramic (IPS Empress) to four different core foundation materials (resin composite, cast metal alloy, lithium disilicate, and dentin), luted with adhesive resin cement (RelyX Unicem). Specimens (N = 56) were fabricated and divided into eight groups (n = 7 per group). Each coping material was luted with self-adhesive resin cement (RelyX Unicem) to the core materials. Bond strength was measured in a Universal Testing Machine (0.5 mm/min). Data were statistically analyzed using a two-way analysis of variance (ANOVA) and Tukey’s HSD tests (alpha = 0.05). Both core (p = 0.000) and coping material type (p = 0.000) significantly affected the mean bond strength (MPa) values. Interaction terms were also significant (p = 0.001). The highest bond strength results were obtained when lithium disilicate was bonded to lithium disilicate (21.48) with the resin cement tested. Lithium disilicate in general presented the highest bond results when bonded to all core materials tested (16.55–21.38) except dentin (3.56). Both cast alloy (2.9) and lithium disilicate (3.56) presented the lowest bond results on dentin followed by cast-alloy-cast alloy combination (3.82)

Retention of zirconium oxide copings using different types of luting agents

Background/purpose: There is limited information in the literature regarding the effect of different luting agents on the bond strength of zirconium oxide (ZrO2) copings to prepared crown. The aim of this in vitro study was to evaluate the ability of different luting agents to retain ZrO2 copings on prepared crowns under laboratory conditions. Materials and methods: Forty-two extracted human maxillary first premolars were prepared with a flat occlusal surface, and rounded line angles, a 5° taper and approximately 3-mm occluso-gingival height. ZrO2 copings were manufactured with buccal and lingual projections to assist removal of the crown after cementation. All copings were airborne-particle abraded with 50 μm aluminum oxide for 15 seconds. The specimens were randomly distributed into three equal groups (n = 14) and cemented with one of three luting agents: resin-modified glass-ionomer cement, self-adhesive resin cement, and adhesive resin cement. The cemented specimens were thermocycled (3000 cycles, 5-55°C), and then removed along the path of insertion using a universal testing machine at 0.5 mm/minute. Statistical analyses of the data were performed using one-way ANOVA (α = 0.05). Results: Mean copings bond strengths were 440 N, 416 N, and 360 N for resin-modified glass-ionomer cement, self-adhesive resin cement, and adhesive resin cement, respectively. There was no statistically significant difference in mean crown retention between the three cementation groups. Conclusion: Retention of ZrO2 copings to prepared crown was not influenced by the types of luting agents

Retention of zirconium oxide copings using different types of luting agents

Background/purpose: There is limited information in the literature regarding the effect of different luting agents on the bond strength of zirconium oxide (ZrO2) copings to prepared crown. The aim of this in vitro study was to evaluate the ability of different luting agents to retain ZrO2 copings on prepared crowns under laboratory conditions. Materials and methods: Forty-two extracted human maxillary first premolars were prepared with a flat occlusal surface, and rounded line angles, a 5° taper and approximately 3-mm occluso-gingival height. ZrO2 copings were manufactured with buccal and lingual projections to assist removal of the crown after cementation. All copings were airborne-particle abraded with 50 μm aluminum oxide for 15 seconds. The specimens were randomly distributed into three equal groups (n = 14) and cemented with one of three luting agents: resin-modified glass-ionomer cement, self-adhesive resin cement, and adhesive resin cement. The cemented specimens were thermocycled (3000 cycles, 5-55°C), and then removed along the path of insertion using a universal testing machine at 0.5 mm/minute. Statistical analyses of the data were performed using one-way ANOVA (α = 0.05). Results: Mean copings bond strengths were 440 N, 416 N, and 360 N for resin-modified glass-ionomer cement, self-adhesive resin cement, and adhesive resin cement, respectively. There was no statistically significant difference in mean crown retention between the three cementation groups. Conclusion: Retention of ZrO2 copings to prepared crown was not influenced by the types of luting agents