Periodontal health in the shortened dental arch

Design Multi-centre randomised controlled clinical trial with two prosthetic intervention arms conducted in 14 dental schools and universities in Germany from October 2000.Case selection Adults aged ≥35 years with bilateral missing molars, both canines and at least one premolar present on each side in one jaw were eligible for inclusion. Participants were randomly allocated to restoration of posterior teeth using a removable partial denture (RPD), or a fixed prosthesis (that is, a bridge) adhering to the concepts of the shortened dental arch (SDA) principles (no replacement posterior to the second molar). Randomisation was completed centrally using randomly permuted blocks stratified by age. Data were collected at baseline (following pre-prosthetic treatment) and patients were followed up at six months, annually for five years, eight years and ten years.Data analysis In total, 215 participants were randomised and allocated to either RPD group (n = 109) or SDA group (n = 106). Intention to treat (ITT) and modified per-protocol analysis were performed on both the RPD group (n = 79) and SDA group (n = 71). Per-protocol analysis was also undertaken on both the RPD group (n = 25) and SDA group (n = 22). The level of significance was set to a two-sided p value of 0.05. The confidence interval was set at 95%.Results When considering the differences in ten-year vertical clinical attachment loss measurements, ITT analysis showed the differences between the RPD and SDA groups were statistically significant (p ≤0.05) in both the study jaw (0.79 mm) and in all teeth (0.69 mm) in favour of the SDA group. Furthermore, the SDA group also performed more favourably in both bleeding on probing and plaque index parameters, with statistically significant changes demonstrated using positive regression coefficients.Conclusions There is evidence of reduced impact on the periodontium from an SDA approach compared to an RPD approach, although the difference is unlikely to be clinically significant.