Crown preparation design: an evidence-based review

Success of Feather Margin Preparation for Full Metal Prosthodontic Crowns in the Canine Teeth in 84 Pet and Working Dogs (2005-2017)

Medical and dental records of Veterinary Dental Specialties and Oral Surgery were searched to identify dogs that received full metal prosthodontic crowns on canine teeth, using a feather or knife edge preparation between 2005 and 2017. A total of 160 teeth in 84 dogs were included in the study. Current follow-up by telephone, electronic mail, or electronic messaging was conducted, in addition to thorough record review for in-person recheck examinations. Treatment was considered successful if the prosthodontic crown was in place and no further or additional injury to the tooth had occurred at the time of reexamination, owner contact, or patient death. Tooth fracture apical to the prosthodontic crown occurred in 2 (1.25%) cases, bond failure between the tooth and the cement or the cement and the crown occurred in a single case (0.625%), and one metal crown required replacement after 3 years due to wear (0.625%), for an overall failure rate of 2.5%. These results suggest that feather preparation of the margin is at least as, if not more, successful as the more commonly accepted and performed chamfer margin, and thus is a successful, practical and durable option for prosthodontic crown treatment in dog canine teeth.

Retrospective Study of 18 Titanium Alloy Crowns Produced by Computer-Aided Design and Manufacturing in Dogs

Computer-aided design (CAD) and computer-aided manufacturing (CAM) technology is routinely used in various fields of human dentistry, particularly prosthodontics. Reverse engineering and additive manufacturing allow the technician to create an easier, faster and more accurate restoration, with a natural design and adequate strength. Eighteen titanium alloy full crowns were produced for canine teeth of 7 working dogs using CAD/CAM technology (3D BioCare, Nobel Biocare). Reasons for crown therapy included abrasion, enamel infraction, and crown fracture. Crown preparation was routinely performed, and impressions were delivered to the laboratory where digital impressions were performed with a lab scanner. Using 3D dental design software, the metal crown was designed and sent for manufacture. Each prosthodontic crown was then carved from a solid titanium alloy block to obtain the final crown. All prosthodontic crowns were an adequate fit, and cementation was routinely performed. Crowns were lost from 2 canine teeth during the dogs' normal working activity, in one case, for 2 times. In all cases, replicas were requested. In the first case, the second cementation was successful. In the second case, the second crown was again lost and only the third cementation was successful. Follow up of all cases range from 12 to 62 months. Mean survival time for the crowns was 58.0 months. Here, CAD/CAM technology is shown to be a useful tool for manufacturing accurate prosthodontic crowns for veterinary patients. Moreover, CAD/CAM enables the production of prosthodontic crown replicas in a very short time and at relatively low cost compared to traditional methods, consequently eliminating the need for at least one anesthetic procedure in the incidence of crown cementation failure.

Cementation of Full Coverage Metal Crowns in Dogs

This step-by-step article describes the technique for cementation of a full metal prosthodontic crown on the maxillary fourth premolar tooth of a dog using a common resin-based cement.

Assessment of 68 Prosthodontic Crowns in 41 Pet and Working Dogs (2000-2012)

A search of the medical and dental records at the Matthew J. Ryan Veterinary Hospital of the University of Pennsylvania was conducted to identify dogs that received full or partial prosthodontic crowns over a 13-year period (2000-2012). Forty-one dogs with a total of 68 prosthodontic crowns were identified. Further criteria for acceptance into the study included presence of complete medical records containing adequate information pertaining to the procedures performed, and current follow-up either by telephone, electronic mail, or via in-person examination. Treatment was considered to be successful when the prosthodontic crown was in place and there was no further structural injury to the tooth upon making contact with the client or at the time of death of the dog confirmed by the client. The mean number of days the prosthodontic crowns remained in place without further injury to the tooth was 1,598 (range, 161-4, 464 days [median, 1,414 days], standard deviation 1,093 days). Bond failure between the cement and the tooth or the cement and the prosthodontic crown occurred in 3 cases (4.4%). Fracture of the prosthodontically treated tooth occurred in an additional 7 cases (10.3%). Treatment was classified as successful in 58 cases (85.3%). The results suggest that prosthodontic crown therapy is a successful, practical, and durable treatment option for protection of previously injured teeth in pet and working dogs.

Quantitative Comparison of Mathematical Models to Measure Surface Area of Canine Teeth Prepared to Receive Full Veneer Crowns in Dogs

OBJECTIVE

This study was performed in order to determine if mathematical modeling of the canine teeth in dogs could be utilized to provide an accurate and reliable estimation of crown surface area that could be used in both a research and a clinical setting.

MATERIALS AND METHODS

Actual surface area (aSA) calculations for 32 stone dies of clinical crown preparations were acquired utilizing a tridimensional (3D) laser scanner and 3D computer-aided design and manufacturing (CAD/CAM) software applications. These calculations were used as a control. Seventeen unique mathematical models from eight geometric shapes were used to calculate estimated surface area (eSA) of each stone die. Linear association and agreement between eSA and aSA calculations were assessed with multiple statistical methods.

RESULTS

All methods of eSA showed a significant linear association with aSA. Five of the mathematical models [right elliptical frustum (H3), right elliptical cone (G3), right pyramidal cone (A3), right circular frustum (F2), and right circular cone (E1)] were superior to the other 12 models.

CONCLUSION

The H3 mathematical model based on the right elliptical frustum provided the most accurate estimate of crown surface area of dog teeth. However, H3 requires the use of laser scans and a 3D CAD software program. As a result, this model would be recommended for research applications. The E1 mathematical model was similar in accuracy to H3 and, given it requires only two measurements and a comparatively simple equation for calculation, this method would be recommended for clinical chair-side use.

Evaluation of the Natural Crown Convergence Angle of Dog Carnassial Teeth

A limiting factor in achieving an ideal crown preparation design is the natural morphology, principally the convergence angle, of the tooth. The natural convergence angle of the carnassial teeth in the dog has not been reported. The aim of the study reported here was to establish the natural crown convergence angle of the maxillary fourth premolar and mandibular first molar teeth in the dog. The natural convergence angle of the carnassial teeth in dogs was large and was not significantly associated with patient weight, age, or skull type.