[EP-7] Laboratory assessment of all-ceramic crown preparations using digital methods
[Abstract]
[Objective]
Incorporation of novel dental materials and related technologies into restorative dentistry resulted in reevaluating the basic principles of tooth crown preparations.1-2 After receiving silicone impressions for single all-ceramic crowns from practicing prosthodontists preparation of master casts and their digitalization was performed. Assessment of tooth preparation parameters, including angle of total occlusal convergence, occlusal clearance, finish line design, two-plane preparation and presence of undercuts was performed on digital data sets and comparison with recommended values were made. The purpose of this study was to use digital data sets to evaluate principal parameters of tooth preparations for all-ceramic crowns.
[Methods]
A total of 100 silicone impressions for fabrication of all-ceramic crowns for maxillary and mandibular first molars were randomly selected. Prepared dental stone master models were scanned (Go3DPro Shining 3D, South Korea) and digitalized using a software (Autoscan-DS-EX, Shining 3D, South Korea). The statistical analysis was performed using SPSS 23.0 package (IBM SPSS Statistics, IBM Corp). One-way ANOVA with Mann-Whitney U test was used for analysis. Level of significance set at p<0.05.
[Results and Discussion]
The mean mesiodistal and buccolingual angles of total occlusal convergence were 28.28° and 27.57°, subsequently. The mean occlusal clearance at central grooves was significantly less compared to that at cusps (2.50±1.06 mm and 1.93±1.01 mm). Regarding the finish line design, 80% of finish lines were non-adequate and undefinable. In total, 79% of tooth preparations were made with undercuts. Among 21 tooth preparations made without undercuts, 4 of them were maxillary first molars, and 17 teeth were mandibular (p=0.002). The tooth preparations made by dental practitioners were different from the clinically accepted parameters recommended for all-ceramic crowns. Postgraduate education should accentuate the principles of tooth preparation for all-ceramic crowns in CAD/CAM era.
[References]
1) Abdulla F, Khamis H, Milosevic A et al. Convergence angles of all-ceramic full crown preparations performed in Dubai private practice. J Clin Exp Dent 2018;10:1192-7. 2) Goodacre CJ, Campagni WV, Aquilino SA. Tooth preparations for complete crowns: an art form based on scientific principles. J Prosthet Dent 2001;85:363-76.
[Objective]
Incorporation of novel dental materials and related technologies into restorative dentistry resulted in reevaluating the basic principles of tooth crown preparations.1-2 After receiving silicone impressions for single all-ceramic crowns from practicing prosthodontists preparation of master casts and their digitalization was performed. Assessment of tooth preparation parameters, including angle of total occlusal convergence, occlusal clearance, finish line design, two-plane preparation and presence of undercuts was performed on digital data sets and comparison with recommended values were made. The purpose of this study was to use digital data sets to evaluate principal parameters of tooth preparations for all-ceramic crowns.
[Methods]
A total of 100 silicone impressions for fabrication of all-ceramic crowns for maxillary and mandibular first molars were randomly selected. Prepared dental stone master models were scanned (Go3DPro Shining 3D, South Korea) and digitalized using a software (Autoscan-DS-EX, Shining 3D, South Korea). The statistical analysis was performed using SPSS 23.0 package (IBM SPSS Statistics, IBM Corp). One-way ANOVA with Mann-Whitney U test was used for analysis. Level of significance set at p<0.05.
[Results and Discussion]
The mean mesiodistal and buccolingual angles of total occlusal convergence were 28.28° and 27.57°, subsequently. The mean occlusal clearance at central grooves was significantly less compared to that at cusps (2.50±1.06 mm and 1.93±1.01 mm). Regarding the finish line design, 80% of finish lines were non-adequate and undefinable. In total, 79% of tooth preparations were made with undercuts. Among 21 tooth preparations made without undercuts, 4 of them were maxillary first molars, and 17 teeth were mandibular (p=0.002). The tooth preparations made by dental practitioners were different from the clinically accepted parameters recommended for all-ceramic crowns. Postgraduate education should accentuate the principles of tooth preparation for all-ceramic crowns in CAD/CAM era.
[References]
1) Abdulla F, Khamis H, Milosevic A et al. Convergence angles of all-ceramic full crown preparations performed in Dubai private practice. J Clin Exp Dent 2018;10:1192-7. 2) Goodacre CJ, Campagni WV, Aquilino SA. Tooth preparations for complete crowns: an art form based on scientific principles. J Prosthet Dent 2001;85:363-76.