Factors Influencing Treatment Outcomes in Mandibular Class II Furcation Defects

Background: Factors influencing treatment outcomes in furcation defects remain to be studied. Therefore, the aim of the study was to evaluate the association between factors and clinical parameters that may influence treatment outcomes in mandibular Class II furcation defects. Methods: Twenty‐seven systemically healthy subjects with a Class II buccal or lingual furcation defect in lower molars were treated. Clinical measurements (probing depth [PD], clinical attachment level [CAL], recession, mobility, plaque index [PI], and bleeding on probing [BOP]) and defect (vertical and horizontal defect depths) were obtained at initial and 6‐month reentry surgeries. Treatment modalities (e.g., nine each in the following three groups: open flap debridement [OFD] alone, bone graft [BG], and bone graft plus a bioabsorbable collagen membrane [BG + C]), anatomic factors (presence of cervical enamel projection, presence of cervical restorations/fixed prosthesis, and location of furcations [buccal or lingual sides; first or second molars]), clinical parameters (initial mobility, initial PD at furcation, initial CAL at furcation, mean initial PD of the tooth, mean initial CAL of the tooth, initial horizontal PD at furcation, initial horizontal/vertical defect depth, PI, and BOP), and background factors (endodontic status, smoking status, and surgeon's experience) were analyzed for associations with probability of clinical improvement. Results: The anatomic factors, clinical parameters, and background information were found to have no effect in influencing treatment outcome with the exception of initial vertical defect depth. An initial vertical defect depth ≥4 mm had a borderline significance ( P = 0.06) of achieving a high probability of having a 1‐mm vertical bone fill. In addition, treatment modality was found to be a major influence factor. Sites treated with BG were 16× more likely to have >50% vertical bone fill than open flap surgery. Furthermore, sites treated with BG were 64× more likely to have a 1‐mm vertical defect fill compared to sites treated with OFD and 16× more likely to have a 2‐mm vertical defect fill compared to sites treated with OFD or BG + C. However, the additional membrane does not enhance the regenerative outcomes achieved by BG alone. Conclusions: Initial vertical defect depth (≥4 mm) and treatment modality (e.g., BG) were found to be the clinical parameter and factor that were associated with high probability of clinical improvement. Sites treated with BG, such as mineralized human cancellous allograft, were more likely to have greater vertical furcation defect fill than the conventional OFD surgery. Additional membrane placement does not enhance the treatment outcome achieved by BG alone.