Feasibility of 3-Dimensional Visual Guides for Preparing Pediatric Zirconia Crowns: An In Vitro Study

Abstract

This study evaluated the feasibility of a tooth preparation guide for prefabricated zirconia crowns (PZCs). Three-dimensional surface data for PZCs of the left maxillary primary first molar and left mandibular primary second molar were obtained using a model scanner. The tooth preparation data were digitally designed to harmonize with the adjacent teeth on the mixed dentition model and visualized using a color-coded map, which presents the required amount of tooth reduction. Twenty participants were recruited for preparing teeth with and without using the tooth preparation guide. The following three parameters were evaluated: tooth preparation time, harmony score, and amount of tooth reduction. The preparation time when using the guide was significantly reduced (p < 0.05), and a significant difference was observed in the harmony scores for the maxillary primary first molar preparation. Furthermore, the amount of tooth reduction was significantly different for both maxillary and mandibular primary molars (p < 0.05) in terms of the occlusal distal surface and buccal line angle in the maxillary primary first molars, and the smooth surfaces, proximal surfaces, and mesial line angles in the mandibular primary second molars. Thus, the results suggest that a tooth preparation guide could facilitate better tooth preparation for PZCs.

Comparison of digital and conventional assessment methods for a single tooth preparation and educational satisfaction

“…Recently, more advanced methods, such as digital grading of tooth preparations using scanners, virtual simulators and software programs by computer‐assisted design and manufacturing (CAD‐CAM), have been used 13–21 . Computer‐aided systems have many feedback options and self‐assessment abilities 22 .…”

“…11,12 Recently, more advanced methods, such as digital grading of tooth preparations using scanners, virtual simulators and software programs by computer-assisted design and manufacturing (CAD-CAM), have been used. [13][14][15][16][17][18][19][20][21] Computer-aided systems have many feedback options and self-assessment abilities. 22 These enable the students to develop their manual skills by immediate evaluation and feedback of their tooth preparation designs.…”

Three‐dimensional evaluation of tooth preparation forms in paediatric zirconia crowns: An in vitro study

“…The typodont teeth were fixed to the dentiform models and digitally scanned using a model scanner (Identica T500 ® ; Medit Inc.). Digital scans of the inner and outer surfaces of PZCs (NuSmile ZR; Orthodontic Technologies) for primary maxillary left first molar and mandibular left second molar were acquired in the same way as in previous studies 7,11 . All digital scans were imported to the 3D modelling software (Meshmixer; Autodesk).…”

“…Digital scans of the inner and outer surfaces of PZCs (NuSmile ZR; Orthodontic Technologies) for primary maxillary left first molar and mandibular left second molar were acquired in the same way as in previous studies. 7,11 All digital scans were imported to the 3D modelling software (Meshmixer; Autodesk). Outer surfaces of PZCs were digitally aligned on the mixed dentition model, and the appropriate size of PZCs was determined to achieve proper mesiodistal…”

Strength and Surface Characteristics of 3D-Printed Resin Crowns for the Primary Molars

“…Compared with the performance of other crowns, preformed zirconia crowns have outstanding esthetics, high strength, and a high level of biocompatibility [8]. However, the time required for tooth preparation varies greatly depending on the skills of the clinician because the crown is so brittle that cannot be modified [9]. Compared with PMCs, zirconia crowns are limited in minimally invasive dentistry because of the extensive tooth reduction required (approximately two-fold anteriorly and 1.8-fold posteriorly) for achieving the passive fit [10].…”