Hall Versus Conventional Preformed Metal Crowns: Radiographic Identification by Pediatric Dentists

Abstract

Background: It is assumed that Conventional preformed metal crowns (PMCs) are usually well adapted to the primary molars, while it has been claimed that the Hall technique (HT) PMC is an oversized, poorly fitting crown with overhanging margins. PMCs, if present in children, are usually identifiable on routine bitewings.

Aim: To investigate if pediatric dentists (PDs) were able to identify or perceive any radiographic differences between HT PMCs versus conventional PMCs and to assess the perception and acceptability of HT by PDs over time.

Method: An online cross-sectional questionnaire of 25 questions survey was sent via global dentistry society groups, to PDs across the globe between 1 st January to the 31st March 2020. It included 10 randomly selected bitewings showing PMCs (five HT and five conventional). A score out of 10 was calculated for the PMCs detection. T-test, Pearson’s and Fischer’s Chisquare, and Odd Ratios (OR) were calculated (p<0.05).

Results: Responses of dentists (N=476) from 58 countries were obtained, with 97% reporting that they used PMCs in their practice. The majority (98.7%) had heard/understood HT, while 79% used it. There was a clear shift, towards supporting the use of the HT, over time with an opinion change OR of 11.154 [95% confidence interval (CI): 6.006- 20.715]. More than two thirds (67%) of the PDs thought that there was no radiographic difference between HT and iii conventional PMCs (out of the 10 bitewings provided), and only five PMCs were identified correctly [average correct score of 4.9 (±1.73) out of 10]. The remainder (33%) who thought there were differences, scored higher than those who had the opposite view (5.31±1.22, and 4.68±1.9 respectively, p<0.00001) No one managed to identify all the 10 PMCs correctly, however, the participants were able to successfully identify HT PMCs on bitewings 4.63 times more than conventional PMCs (OR for successfully identifying HT PMCs; 24.857 [CI: 15.059- 41.028] compared to an OR for successfully identifying conventional PMCs; 5.361 [CI: 3.089- 9.304], p<0.0001).

Conclusion: Most of the surveyed PDs identified the PMC type in only half of bitewing radiographs provided. Despite that they perceived that there was no clear radiographic difference between HT and conventional PMCs on bitewings radiographs, the chance of them recognizing HT PMCs on these bitewings was almost five times higher than conventional PMCs. There was a clear supportive shift in opinion over time, for the use of the HT.