Abstract:

Objective　The aim of this studywas to evaluate quantitativelythe effectiveness and feasibility of the modified su- pracrestal fiberotomy (MSF) and the contact point reproximation (CPR) in decreasing the relapse of anterior segments rotating and/ or crowding after orthodontic treatment.Methods　Atotal of 129 patientswith crowding and/or rotated anteriorteethwere selected for this study, and the average age was 13·07 years (54 males, 75 females). The modified supracrestal fiberotomywas performed on the anterior segments of patients in the experimental group (48 cases). After the anterior teethwere aligned, 23 of the 48 cases received a further treatment of the contact point reproximation on the anterior segments (the subgroup of MSF+CPR), and the other 25 sub- jects did not receive this treatment (the subgroup ofMSF). The control group consisted of 81 cases. All cases wore Hawley retainers for 1·8 to 2·3 years, and all the patientswere revisited 2·4years postretention. The maxillary and mandibular dental models of all the patients were taken before treatment (T1), at the end of the treatment (T2) and 2·4 years postretention (T3).Results　The relapse rate in the experimental group [(T3-T2)/T1×100%] was 21·6%, lowerthan that in the control group (P<0·001). The relapse rate of mandible in the subgroup ofMSF+CPRwas 6·56% lowerthan that of the subgroup ofMSF (P<0·05). But the relapse rate of maxillary in the subgroups ofMSF+CPRwas similar as that of the subgroup ofMSF (P>0·05).Conclusion　The modified su- pracrestal fiberotomy can effectively alleviate relapse after orthodontic treatment of the crowding and/or rotation of anterior teeth. The treatment combining MSF and CPR can help maintain the stability of post-retention of mandibular anterior teeth.

Key words: modified supracrestal fiberotomy, contact point reproximation, rotating/crowding relapse, irregularity in- dex