Natural 4-year periodontal progression of mandibular first molars in Chinese villagers based on radiographic records.

Abstract

To report 4-year natural periodontal progression of mandibular first molars based on radiographic records in 15 to 44-year-old Chinese villagers. In 1992 (N=486) and 1996 (N=413), panoramic radiographs were recorded. Tooth loss of mandibular first molars was calculated. Relative bone height (RBH), intrabony defect (IBD) depth, and furcation involvement (FI) were measured on 918 and 755 mandibular first molars in 1992 and 1996, respectively. The progression of the three parameters and their relationship with widened periodontal ligament space (WPDL) were analyzed. In 1992, of 31 lost mandibular first molars, 29 belonged to the 35- to 44-year age group. At 4-year follow-up, five of eight lost teeth belonged to the 35- to 44-year age group. RBH decreased from 83% in 1992 to 77% in 1996. RBH progression was significantly faster in the 25- to 34- and 35- to 44-year age groups than in the 15- to 24-year age group. The mean IBD depth was 2.81±0.55mm (n=32) in 1992 and 3.70 ± 0.73mm (n=33) in 1996. Prevalence of FI increased from 20.8% to 27.4%. Teeth with WPDL showed greater RBH and IBD progression than those without WPDL (RBH: 12%±1% versus 6%±0.01%, P < 0.001; IBD depth: 0.31±0.08versus 0.01±0.00mm, P <0.001). FI-area progression in teeth with WPDL showed a trend of greater expansion than in those without WPDL (0.92±0.18versus 0.56±0.11mm2 , P =0.051). Tooth loss mainly occurred in the 35- to 44-year age group. RBH progression was faster in the 25- to 44-year age group. WPDL was associated with progression of RBH, IBDs, and FI.