| Objective: The objectives of this study were to evaluate the reliability of digital oral scanning(DOS)combined with cone beam computed tomography(CBCT)technique for measuring the thickness of the labial gingival and bone plates in the aesthetic area of the maxillary anterior teeth,to analyze the correlation between the thickness of the gingival and the bone plate,and to compare the differences among various parameters of different gingival biotypes.Materials and methods: In this study,30 young volunteers were selected,including18 males and 12 females,with an average age of 22,involving 172 maxillary anterior teeth.First,gingival biotypes(GB)were divided into thin,intermediate and thick gingival types by transparency probing(TP)method.Then,the imaging data of all subjects were obtained using CBCT with radiopaque template technique(M1)and digital oral scanning(DOS)combined with CBCT imaging technique(M2),and the gingival thickness(GT)at the cemento-enamel junction(CEJ)as well as alveolar ridge crest(ARC)were measured on the median sagittal plane.Meanwhile,the GT and Bone thickness(BT)at 2?4 and 6 mm apical to CEJ,and the distance between CEJ and ARC were measured using the M2 method.One week later,the repeatability test was performed on all the above measurements.Finally,the consistency of M1 and M2 in GT measurement was evaluated,the differences among various parameters of different GB was analyzed,and the correlation between GT and BT were investigatedfurtherly.Results:1.There was no significant difference between the GT measurements using M1 and M2 methods at the position of CEJ and ARC for maxillary anterior teeth(t=5.35,P=1.09).2.Among the 172 maxillary anterior teeth,thick GB could be found in 44 cases,intermediate GB in 87 cases,and thin GB in 41 cases.The GT of the three GB(thick,intermediate and thin)at CEJ was: 1.04±0.33 mm,0.96± 0.29 mm,and 0.93± 0.18 mm,respectively,while at ARC was 1.11±0.16 mm,0.96± 0.16 mm,and 0.94±0.16 mm,respectively.In the central incisor and lateral incisor groups,the GT of the three GB at CEJ showed significant differences,but the difference between the canine groups only could be found between thick and thin GB.At ARC,there was no significant difference in GT between the three GB in each tooth position of the upper anterior teeth.The distances of CEJ-ARC corresponding to the three GB was 1.83 ±0.47 mm,1.88 ± 0.66 mm,2.06 ± 0.57 mm,respectively,but with no statistical difference.3.There were negative correlations between GT and BT at 2?4 mm apical to CEJ in the central incisor and lateral incisor groups and at 2 mm apical to CEJ in the canine groups,while only weak negative correlations or even no correlations could be found in the other sites.In addition,the ratio of BT < 1 mm of the labial of central incisor,lateral incisor and canine was 96.7%,97.8% and 90.2%,respectively,and the proportions of GT < 1.5 mm were 92%,95% and 97%,respectively.Conclusion:(1)DOS combined with CBCT imaging technique should be a reliable method for the measurement of gingival thickness.(2)There were strong negative correlations between GT and BT at the labial side of maxillary anterior teeth at 2?4 mm apical to CEJ,but no significant correlations at 6mm apical to CEJ.With clinical point of view,cautious should be taken to evaluate the labial BT based on GB.(3)On the labial side of the maxillary anterior teeth,GT and BT were all very limited(GT < 1.5 mm,BT < 1 mm).Therefore,for the cases of implant restoration in theaesthetic area(especial immediate implant insertion),the implantation sites should be carefully evaluated to formulate the reasonable treatment strategy. |
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