Change over time in intra-arch contact point tightness.

PURPOSE: To examine contact point (CP) tightness of the mandibular dental arch in cases with a unilateral first molar (M1) missing, and also investigate the influence of time since extraction on CPs tightness. METHODS: CPs tightness was measured with a tightness of dental contact point device in 29 patients (9 men, 20 women), mean age 32.6 +/- 6.5 years, with a unilateral missing M1 and no periodontal disease. ANOVA with repeated measures test was used to statistically compare CP tightness between extraction (E) and non-extraction (NE) sides, at significant level of P < or = 0.05, with CPNE serving as internal control. RESULTS: The first CP adjacent to the extraction site between the first and second premolar (CP4-5,E) was significantly (P < or = 0.001) lower (29%) than CP4-5,NE. The difference (NE-E) was reduced to 20% at the more anterior CP (CP3-4,E) which was close to but non-significant (P < or = 0.09). Further anterior CPs (CP2-3, CP1-2) showed a non-significant difference between homologous CPs. Thus, reduction in CP tightness was confined to two adjacent teeth anterior to the extraction site. The tightness reduction of the posterior dentition (CP4-5 + CP3-4) was obtained 3 years post-extraction and subsequently maintained a constant asymmetry ratio (E/NE = 0.68-0.80) up to 14 years post-extraction.