Imaging Sci Dent.  2017 Sep;47(3):181-187. 10.5624/isd.2017.47.3.181.

Analysis of the root position of the maxillary incisors in the alveolar bone using cone-beam computed tomography

• Jung YH
• Cho BH
• Hwang JJ

• KMID: 2390083
• DOI: http://doi.org/10.5624/isd.2017.47.3.181

Abstract

PURPOSE
The purpose of this study was to measure the buccal bone thickness and angulation of the maxillary incisors and to analyze the correlation between these parameters and the root position in the alveolar bone using cone-beam computed tomography (CBCT).
MATERIALS AND METHODS
CBCT images of 398 maxillary central and lateral incisors from 199 patients were retrospectively reviewed. The root position in the alveolar bone was classified as buccal, middle, or palatal, and the buccal type was further classified into subtypes I, II, and III. In addition, the buccolingual inclination of the tooth and buccal bone thickness were evaluated.
RESULTS
A majority of the maxillary incisors were positioned more buccally within the alveolar bone, and only 2 lateral incisors (0.5%) were positioned more palatally. The angulation of buccal subtype III was the greatest and that of the middle type was the lowest. Most of the maxillary incisors exhibited a thin facial bone wall, and the lateral incisors had a significantly thinner buccal bone than the central incisors. The buccal bone of buccal subtypes II and III was significantly thinner than that of buccal subtype I.
CONCLUSION
A majority of the maxillary incisor roots were positioned close to the buccal cortical plate and had a thin buccal bone wall. Significant relationships were observed between the root position in the alveolar bone, the angulation of the tooth in the alveolar bone, and buccal bone thickness. CBCT analyses of the buccal bone and sagittal root position are recommended for the selection of the appropriate treatment approach.

Keyword

Maxilla; Incisor; Tooth Root; Cone-Beam Computed Tomography

MeSH Terms

Cerebral Cortex
Cone-Beam Computed Tomography*
Facial Bones
Humans
Incisor*
Maxilla
Retrospective Studies
Tooth
Tooth Root

Figure

• 

  Fig. 1 The root position of the incisors in the alveolar bone is classified as the buccal, middle, or palatal type. A. Buccal type: the apical point of the incisor is within the buccal third of the alveolar bone and the root is closer to the buccal bone wall. B. Middle type: the apical point of the incisor is within the middle third of the alveolar bone and the buccal and palatal bone walls are approximately equal in thickness. C. Palatal type: the apical point of the incisor is within the palatal third of the alveolar bone and the root is closer to the palatal bone wall.

• 

  Fig. 2 The buccal type is further classified as follows. A. Subtype I: the incisor root is covered by the buccal bone wall, and the bone thickness increases toward the apex. B. Subtype II: the incisor root is covered by a thinner buccal bone wall than in subtype I and the bone thickness does not noticeably increase toward the apex that is covered by the bone tissue in the long axis of the tooth. C. Subtype III: the axis of the apex is angulated very buccally and the apex is not covered by the bone tissue in the long axis of the tooth.

• 

  Fig. 3 The angle between the long axis of the tooth and the long axis of the corresponding alveolar bone is measured.

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  Fig. 4 The thickness of the buccal bone is measured at the alveolar crest; 2, 4, and 6 mm apical to the alveolar crest; and at the root apex.

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