Physiological Wear of Natural Anterior Teeth after Two Years

Objectives: The objective of this study was to determine volume loss due to physiological wear of natural anterior teeth after two years.

Methods: Eighteen subjects with good medical and dental health were recruited for this study.  Impressions of maxillary and mandibular arches were taken using polyvinyl siloxane impression material at baseline, one-year, and two-year appointments.  Replica models were made using synthetic stone.  These models were marked as originals, one-year, and two-year models. Volume loss or wear of both maxillary and mandibular natural central incisors and canines was obtained by comparing the surface of the original model with those of the one-year and two-year models using 3D laser scanner. Statistical analysis of the mean values was performed using Kruskal-Wallis test and Dunn's multiple comparison test.

Results: The means volume losses of natural anterior teeth are summarized in Table 1. Even the increases in means volume losses of maxillary central incisor and canines were observed after two years, but no significant differences were found between the mean volume loss of all anterior teeth at one year and the means volume loss at two year. The means volume losses of maxillary anterior teeth were significantly higher than those of mandibular anterior teeth after two years (P< 0.05).

Table 1. The mean volume losses of natural anterior teeth

Anterior teeth	Means volume loss of central incisors  (mm3)		Means volume loss of canines  (mm3)
	One-year	Two-year	One-year	Two-year
Maxillary	0.29±0.14	0.46±0.27	0.21±0.06	0.31±0.07
Mandibular	0.13±0.07	0.09±0.06	0.15±0.05	0.07±0.02

Conclusions: No significant differences were found between the mean volume loss of all anterior teeth at one year and the means volume loss at two year. The means volume losses of maxillary anterior teeth were significantly higher than those of mandibular anterior teeth after two years.