Relationship Between Crown-to-root Ratio And Alveolar Bone Support In Patients With Unilateral Cleft Lip And Alveolus

Objectives: To evaluate the tooth lengths,crown-to-root ratios(CRR)and alveolar bone support(ABS)around cleft-adjacent maxillary central incisors(U1s)in patients with unilateral cleft lip and alveolus(UCLA)and to investigate the relationships between the CRR and ABS.Methods: CBCT data from 58 non-syndromic patients with UCLA(36males,22females;mean age =12.65±3.64 years)were evaluated.Crown height and root length,alveolar bone thickness(ABT)and the distances between the cementoenamel junction(CEJ)and alveolar bone crest(AC)on four surfaces of cleft-adjacent U1 were measured and compared with those of non-cleft side in the same patients.CRR and frequency of dehiscence were calculated and comparisons were also made between cleft and non-cleft sides.Regression analysis was performed to explore the association between CRR and ABS.Results: The CRR of cleft-adjacent U1 and alveolar bone crest heights(ACHs)on the four surfaces were significantly greater than those of non-cleft side.(P<0.01).3mm-labial,all lingual and apico-distal ABTs decreased on the cleft side(P<0.01).A positive correlation was found between lingual ACH and CRR(R=0.316,P<0.05),between the 3mm(R=0.417,P<0.05)and 6mm-labial(R=0.448,P<0.05)ABT and CRR.A negative correlation was found between the 3mm and 6mm-labial ABTs and the root length.Conclusions: It can be suggested that the CRR is related to alveolar bone crest height and alveolar bone thickness.The lingual ACH,the 3mm and 6mm-labial ABTs tend to increase with the increasing CRR.