3D Morphometric Analysis of Human Primary Second Molar Crowns and Its Implications on Interceptive Orthodontics

The second primary molar represents an anchorage element in interceptive orthodontics. The present study aims to analyze the 3D morphology of primary second molars in order to provide reference data and implications about the development of orthodontic bands for second primary molars. Digital models of dental arches from 150 subjects in primary or mixed dentition were analyzed. Six dimensional variables were digitally measured for each second primary molar, and the mean and standard error of the mean (SEM) were calculated and compared applying Student t-test statistical analysis. The mean value results show statistically significant dimensional differences between the upper and lower teeth, (mostly p < 0.0001), except for the variable h1, while only the variable h1 showed significant differences between the antimetric teeth (left and right). The dimensional variations between the right and left molars were considerably minor compared to those found by comparing the upper and lower arches. A significantly higher dimension of the lower molars and a more rectangular shape were observed.

Contamination assessment of orthodontic bands after different pre-cleaning methods at a tertiary care hospital

INTRODUCTION

Infection control in dentistry is a major concern due to risk of transmission of communicable diseases. The aim of this study is to evaluate and compare the efficacy of various pre-cleaning methods for the tried-in orthodontic bands.

MATERIAL AND METHODS

An in-vitro experimental study was conducted at the Central Sterilization Services Department (Dental Clinic) and the Microbiology lab at our university hospital. A total of 130 bands were included in our study which comprised 10 controls and the rest were equally divided into three groups according to the pre-cleaning methods, i.e. manual scrubbing, enzymatic solution and a combination of both. The orthodontic bands were incubated in the brain heart infusion broth at 37 °C for five days after pre-cleaning and sterilisation in a steam autoclave and were assessed for any bacterial growth. The chi-square test was applied to determine any significant association between the various pre-cleaning methods and the frequency of bands that showed growth. Effect size was calculated using the phi coefficient.

RESULTS

The enzyme method revealed 5% of the sample to exhibit bacterial growth, whereas manual scrubbing and the combination of both showed no growth. There was no statistically significant difference among the three methods (P = 0.131). Further investigations showed the presence of Staphylococcus non-aureus bacterial species in contaminated bands from group II.

CONCLUSIONS

All pre-cleaning methods were found to be equally effective in the decontamination of bands. Hence, the tried-in bands can be safely reused after pre-cleaning and sterilisation.

Microleakage under orthodontic bands cemented with nano-hydroxyapatite-modified glass ionomer

OBJECTIVES

To estimate the in vivo effect of nano-hydroxyapatite (HA) modification of banding glass-ionomer cement on microleakage under orthodontic bands.

MATERIALS AND METHODS

Eighty noncarious premolars scheduled for extraction in 20 orthodontic patients were randomly divided into four groups. Grouping was based on the ratio of nano-HA (0%, 5%, 10%, 15% by weight) added to the luting glass-ionomer cement (GIC) Ketac-Cem, which was used for cementation of prefabricated micro-etched orthodontic bands. Dye penetration method was used for microleakage evaluation at the cement-band and cement-enamel interfaces. Statistical evaluation was performed with a Kruskal-Wallis test and a Mann-Whitney U-test, and a Bonferroni-adjusted significance level was calculated.

RESULTS

Bands cemented with conventional GIC showed the highest microleakage scores in comparison to those cemented with nano-HA-modified GIC. No significant difference was found between teeth banded with 10% and 15% modified GIC.

CONCLUSIONS

Modification of the banding GIC with 15% nano-HA revealed a positive effect on reducing microleakage around orthodontic bands.