| ObjectivesProgress with the technology uninterrupted growth, the definition of successful implantation is not any more the long-term stability of implant but the long-term stability of soft tissue and aesthetics. But unfortunately, the unpredictability of the soft tissue in long-term observation always accompanies aesthetic complications,as recession of soft tissue and exposure of emerging abutment. Sufficient multi-center studies have proved that the diameter of implant, the facial bone thickness and gingival biotypes are the most critical influences on aesthetic complications. Presently,ignoring the unmodifiable gingival biotypes and the thickness of facial bone wall, the3-D position of implant was the key to reach the pick of aesthetics. So, it is important to access to the information including the thickness of facial bone wall, the axial angular of tooth and its alveolar bone, for achieving best long-term aesthetic results.There has been one study about classification of maxillary central incisors determined based on CBCT images. In our study, all the maxillary anterior teeth were included, and quantitative classifications with relative recommendations were provided.The present study was aimed to analyze the anatomical structure of maxillary anterior teeth including the thickness of facial bone wall and the axial angular between tooth and alveolar, to offer classification for the teeth by using CBCT, and to provide the data of this retrospective anatomical structure study and the advice for formulating treatment plan before immediate implantation in aesthetic zone.MethodsPart one was a study of the anatomical structure of alveolar bone in maxillary anterior teeth zone. Part two was a study of the positional relationship between themaxillary anterior teeth and the relative alveolar bone.One hundred patients, hospitalized at stomatology center, Shenzhen People’s hospital, second clinical medical college of Jinan university, including 600 maxillary anterior teeth, were recruited randomly. The thickness at 6 positions of labial and palatal bone wall and the distance from cervical CEJ to ABC was measured, and the classifications were established based on the thickness of alveolar bone in part one.The axial angular between tooth and its relative alveolar process was measured, and the classifications were established based on the angular and the occurring of undercut at the apical facial bone wall in part two.ResultsPart 11. The mean distance from cervical CEJ to ABC of facial and palatal were 1.92±0.86 mm、1.42±0.68 mm in central incisor, 1.89±0.91 mm、1.36±0.77 mm in lateral incisor, and 2.08 ± 1.12 mm 、1.54 ± 0.88 mm in canine, all of which increased with age. And this facial distance at the age between 50 to 59 was 1mm longer than the age between 19 to 29.2. The thickness of facial bone wall was thinnest at mid-root, which was 0.83±0.33 mm for central incisor, 1.42±0.68 mm for lateral incisor, and 0.67±0.41 mm for canine. And it was thickness at the position of the apical. The proportions of facial bone wall thickness at the position of 4 mm bellow CEJ in 0.1 mm to 1.0mm section of 3 kinds of teeth were 66 %,68 %,53.5 %, and at the position of the apical were 81 %,91 %,86 %.3. Palatal bone wall thickness showed an increasing phenomenon from the crest to the apex, and a mean thickness of different teeth at apical position was 7.76±1.44 mm, 6.60 ± 1.72 mm and 9.81 ± 2.65 mm, with the proportion of the thickness≥6.0 mm was 81.0 %,84.5 % and 82.5 %. The thickness at the position of 4 mm bellow CEJ mainly ranged from 1.0 mm to 3.0 mm, with a mean thickness of 1.91±1.29 mm for central incisor, 1.44±0.54 mm for lateral incisorand 1.48±0.59 mm for canine. The thickness at the apical position mainly ranged from 2.0 mm to 3.0 mm.4. There were 85.5 % of anterior teeth belong to type I alveolar bone, 5.2 % belong to type II, and 9.3 % belong to type III. There was 21.5 % of type III alveolar bone for lateral incisor, while canine(5 %) and lateral incisor(1.5 %) were less.Part 21. The mean axial angles(without negative measured value)was 17.32±6.31°for central incisor, 17.06±7.35°for lateral incisor,and 19.52±6.28°for canine.The axial angles all teeth were mainly in 10°to 20°section, while 14.0% of canines were in 10°to 20°section.2. The axial angles between the tooth and its relative alveolar process were categorized into three styles. Style A occupied 11 %,While style B occupied52 %, 30.0 % of which with undercut at the apical facial bone wall. Style C occupied 37 %, 77% of which were with deeper undercut. 17.5 % of lateral incisors belonged to style A, while canines(7.0 %) were less and central incisors(8.0 %) were least.Conclusions1. The mean distance from cervical CEJ to ABC of facial and palatal were with an overall tendency to increase with age.2. A thin facial alveolar bone wall(<1 mm) was usually present at the position of 4mm below CEJ and mid-root(78.3 %). Palatal bone wall thickness showed an increasing phenomenon from the crest to the apex, and the mean thickness at apical position was>6 mm.3. Type II was the best kind of alveolar for immediately implantation, while type I was the most comment one, while type III was the most technical one.4. The axial angular of maxillary anterior teeth and alveolar process was meanly in10°to 20°section, and the greater the angular was, the more undercut at the apical facial bone wall happened.5. Style A was the best kind of axial angular for immediate implant and immediate restoration. But,besides the angular, style B and C should pay more attention on proctecting the thin buccal bone. |
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