Survival of Single-Unit Porcelain-Fused-to-Metal (PFM) and Metal Crowns Placed by Students at an Australian University Dental Clinic over a Five-Year Period.

Chris Carey,Nick Del Din,Menaka Abuzar,Nigel D Robb,Jessica Lamb,Hazel Wright

doi:10.3390/dj9060060

Chris Carey, Nick Del Din + Show 4 more

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https://doi.org/10.3390/dj9060060

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Journal: Dentistry journal	Publication Date: May 28, 2021
Citations: 3	License type: CC BY 4.0

Affiliation: Griffith University, University of Melbourne

Abstract

The aim of this retrospective study was to determine the survival rate of single-unit porcelain-fused-to-metal (PFM) and metal crowns placed by dental students at an Australian university undergraduate dental clinic over a five-year period. Complications and the incidences of crown failures were recorded. Clinical records pertaining to single-unit PFM and metal crowns inserted over a five-year period were reviewed, including patient-related, tooth-related, and procedural factors for each crown. Crowns were evaluated as surviving, surviving with complications, or failed. Kaplan–Meier statistical analysis was used to estimate survival rate., This study is based on a sample of 232 (78.4%) PFM crowns and 64 (21.6%) metal crowns inserted between 2014 and 2018. Cumulatively, 224 (75.7%) were surviving, 48 (16.2%) were surviving but previously had complications, and 24 (8.1%) failed. The 5-year cumulative survival rate of all PFM and metal crowns was 83.9% (0.839 ± 0.038, Kaplan–Meier). The average survival time for all crowns was 4.432 ± 0.089 years. Comparatively, PFM crowns had a higher survival rate at 1 year (0.972 ± 0.010) and 2 years (0.919 ± 0.017), compared to metal crowns at 1 year (0.964 ± 0.011) and 2 years (0.894± 0.018). The survival rate of metal crowns remained constant from 2 years to 4 years and thereafter, whereas there was a continued decline in the survival rate of PFM crowns to 83.2% (0.832 ± 0.038) at 4 years and thereafter. Crowns placed on premolars had the highest cumulative survival rate whereas those placed on molars exhibited the lowest survival rate for the duration of the study period. Despite single-unit PFM crowns having a higher 1- and 2-year survival rate compared to metal crowns, metal crowns had a higher survival rate at 4 years and thereafter. Survival rates are comparable to previous studies.

Highlights

Porcelain-fused-to-metal (PFM) and metal crowns have been used to restore broken down teeth for the past three decades
The aim of this study was to investigate the survival rate of both single-unit PFM and metal crowns placed by dental students at an Australian university undergraduate dental clinic over a five-year period, as well as analysing the number and type of complications and failures
Over the five-year period, 296 PFM and metal single-unit crowns that were placed in the undergraduate clinic by dental students in 234 patients of which 157 (52.7%) were male and 141 (47.3%) were female

Summary

Introduction

Porcelain-fused-to-metal (PFM) and metal crowns have been used to restore broken down teeth for the past three decades. Dental curricula in Australia are designed to provide undergraduates the knowledge and clinical skills required to provide PFM, metal, and ceramic crowns. Students commence learning fixed prosthodontics on mannikins in the pre-clinical simulation laboratory and enhance these skills by treating patients in the later years of the program. The students are closely supervised in the clinics by experienced teachers, and it is expected that these crowns remain functional and survive intra orally for an acceptable length of time. Few studies have evaluated the survival rates of indirect restorations placed by dental students. Those that have, considered restorations placed over 30 years ago [1], were conducted outside Australia [1,2], are related to restorations other than single-unit crowns [3,4]

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