A cone-beam computed tomographic study comparing characteristics of maxillary anterior regional alveolar bone remodeling under two reference systems

doi:10.3969/j.issn.1674-8115.2025.11.010

Abstract

Abstract:

Objective ·To compare differences in the bone remodeling/tooth movement ratio (B/T ratio) between the skeletal stable structure reference system and the dental long-axis reference system among extraction patients (extracted bilateral first premolars) undergoing maxillary anterior retraction and intrusion with micro-implant anchorages. Methods ·A total of 23 samples were retrospectively analyzed. Pretreatment and posttreatment cone-beam computed tomography (CBCT) data, along with pretreatment demographic (age, gender) and cephalometric parameters (ANB angle and FMA angle), were collected from patient records. All subjects underwent standardized orthodontic treatment protocols. Using Dolphin Imaging software, pretreatment and posttreatment CBCT images were superimposed. Labial inclination changes, incisal edge sagittal displacements, root apex sagittal displacements, and intrusion values were measured under skeletal stable structure reference system. For both group G (skeletal stable structure) and group Y (dental long-axis), tooth movement distances, bone remodeling distances, and B/T ratios were measured at three levels: alveolar crest (Level 1), mid-root (Level 2), and root apex (Level 3). Normalized data were compared to evaluate intergroup differences in B/T ratios. Results ·Average ANB and FMA angles were 6.00 °±2.08° and 30.24 °±5.95°, respectively, consistent with skeletal Class Ⅱ malocclusion and vertical hyperdivergence tendencies. The maxillary central incisors exhibited sagittal displacement gradients in which incisal edge displacements [right: (6.07±2.58) mm; left: (6.33±2.27) mm] exceeded apical displacements [right: (3.92±2.06) mm; left:(3.90±2.27) mm]. Concurrently, intrusion values demonstrated comparable vertical changes bilaterally [right: (2.90±1.51) mm; left: (2.87±1.80) mm], accompanied by labial inclination changes of 4.26°±9.19° (right) and 4.00°±8.84° (left). In group G, tooth movement distance progressively decreased from Level 1 to Level 3, whereas no such gradient was observed in group Y. Both groups demonstrated decreasing bone remodeling distances and B/T ratios from Level 1 to Level 3. After normalization, statistically significant intergroup differences (P<0.05) were identified across all measurement levels except for the B/T ratio at Level 1 of the left maxillary central incisor. Conclusion ·When evaluating alveolar bone remodeling during orthodontic retraction and intrusion of maxillary anterior teeth with micro-implant anchorages, the skeletal stable structure reference system provides more accurate assessments than the dental long-axis reference system, as the latter is susceptible to displacement artifacts inherent to the reference itself.

Key words: bone remodeling, tooth movement, cone-beam computed tomography

CLC Number:

R783

LI Lulu, WU Jianyong. A cone-beam computed tomographic study comparing characteristics of maxillary anterior regional alveolar bone remodeling under two reference systems[J]. Journal of Shanghai Jiao Tong University (Medical Science), 2025, 45(11): 1507-1514.

Figures/Tables 6

TrendMD

References 27

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Alveolar bone level	Tooth movement/mm	Alveolar bone remodeling/mm	B/T Ratio
T11
Level 1	3.49±2.21	2.83±1.78	0.84(0.76, 1.03)
Level 2	3.05±2.29	1.96±1.46	0.75(0.59, 0.90)
Level 3	2.09±2.51	1.09±1.27	0.59(0.47, 0.81)
T21
Level 1	3.55±2.06	2.83±1.65	0.74(0.67, 0.98)
Level 2	3.18±2.18	2.00±1.42	0.63(0.54, 0.76)
Level 3	2.81±2.54	1.29±1.25	0.55(0.44, 0.61)

Alveolar bone level	Tooth movement/mm	Alveolar bone remodeling/mm	B/T Ratio
T11
Level 1	3.49±2.21	2.83±1.78	0.84(0.76, 1.03)
Level 2	3.05±2.29	1.96±1.46	0.75(0.59, 0.90)
Level 3	2.09±2.51	1.09±1.27	0.59(0.47, 0.81)
T21
Level 1	3.55±2.06	2.83±1.65	0.74(0.67, 0.98)
Level 2	3.18±2.18	2.00±1.42	0.63(0.54, 0.76)
Level 3	2.81±2.54	1.29±1.25	0.55(0.44, 0.61)

Alveolar bone level	Tooth movement/mm	Alveolar bone remodeling/mm	B/T Ratio
T11
Level 1	4.93±1.87	4.28±1.27	0.88(0.79, 1.00)
Level 2	4.71±1.98	3.77±1.30	0.84(0.73, 0.92)
Level 3	4.54±2.15	2.92±1.29	0.72(0.49, 0.81)
T21
Level 1	5.08±1.60	4.40±1.23	0.89(0.82, 0.97)
Level 2	4.94±1.69	3.79±1.03	0.81(0.65, 0.93)
Level 3	5.00±1.90	3.01±1.11	0.64(0.50, 0.73)

Alveolar bone level	Tooth movement/mm	Alveolar bone remodeling/mm	B/T Ratio
T11
Level 1	4.93±1.87	4.28±1.27	0.88(0.79, 1.00)
Level 2	4.71±1.98	3.77±1.30	0.84(0.73, 0.92)
Level 3	4.54±2.15	2.92±1.29	0.72(0.49, 0.81)
T21
Level 1	5.08±1.60	4.40±1.23	0.89(0.82, 0.97)
Level 2	4.94±1.69	3.79±1.03	0.81(0.65, 0.93)
Level 3	5.00±1.90	3.01±1.11	0.64(0.50, 0.73)

Group		M(Q₁, Q₃)	Z value	P value
T11 B/T Ratio
Level 1	Group G	0.58(0.47, 0.86)	-2.798	0.005
Level 1	Group Y	0.35(0.19, 0.56)	-2.798	0.005
Level 2	Group G	0.56(0.46, 0.62)	-4.010	0.000
Level 2	Group Y	0.28(0.21, 0.33)	-4.010	0.000
Level 3	Group G	0.81(0.70, 0.90)	-3.498	0.000
Level 3	Group Y	0.40(0.25, 0.46)	-3.498	0.000
T21 B/T Ratio
Level 1	Group G	0.43(0.28, 0.86)	-0.016	0.987
Level 1	Group Y	0.54(0.41, 0.72)	-0.016	0.987
Level 2	Group G	0.37(0.27, 0.51)	-1.977	0.048
Level 2	Group Y	0.57(0.22, 0.83)	-1.977	0.048
Level 3	Group G	0.65(0.53, 0.70)	-2.419	0.016
Level 3	Group Y	0.51(0.34, 0.62)	-2.419	0.016