Follow-up study evaluating morphological changes in alveolar bone in the maxillary anterior region after extraction retraction in adult patients treated with clear aligners on the basis of cone beam computed tomography data

doi:10.7518/hxkq.2025.2025316

Abstract

Abstract:

Objective Alveolar bone height and thickness changes in the maxillary anterior region were assessed before treatment (T1), after treatment (T2), and during the retention phase (T3) in patients with maxillary protrusion treated with clear aligners combined with premolar extraction. The aim was to provide clinical insights for safely retracting anterior teeth with clear aligners. Methods This retrospective study included 15 patients (2 males and 13 females) with maxillary protrusion, who underwent bilateral maxillary first premolar extraction and anterior tooth retraction with clear aligners. Cone beam computed tomography images were collected at T1, T2, and T3 (≥18 mon-ths post-treatment) for the measurement of vertical alveolar bone height (labial, palatal, mesial, and distal aspects) and horizontal alveolar bone thickness (labial, palatal, and total). Statistical analysis was performed using SPSS 26.0, and changes across phases and correlations were assessed. Results After orthodontic treatment, the palatal and mesial alveolar bone height of the maxillary anterior teeth significantly decreased (P<0.05). Concurrently, the labial midroot and apical thickness of the maxillary central incisors showed a significant increase, whereas the palatal cervical alveolar bone of the maxillary lateral incisors and canines exhibited significant thinning (P<0.05). At T3, the labiopalatal alveolar bone height of the maxillary central incisors significantly increased (palatal height increase: 0.46 mm±0.57 mm; P<0.05). Although the palatal alveolar bone thickness of the maxillary lateral incisors and canines continued to decrease, the differences were not statistically significant (P>0.05). A negative correlation was observed between alveolar bone resorption during treatment and bone regeneration during retention (labial height of maxillary central incisors: r=-0.597, P<0.05). Conclusion After the retraction of maxillary anterior teeth with clear aligners, the alveolar bone height on the mesial and palatal sides of the upper anterior teeth showed considerable reduction. The palatal alveolar bone thickness at the cervical and middle root levels of the upper lateral incisors and canines decreased remarkably. By contrast, the labial alveolar bone thickness at the middle and apical root levels of the upper central incisors significantly increased. At T3-T2, the partial recovery of alveolar bone height and thickness was observed, but pretreatment levels were not reached. Notably, the degree of bone resorption during treatment may influence the remodeling potential at T3.

Key words: clear aligner, anterior tooth retraction, maxillary protrusion, alveolar bone height, alveolar bone thickness

CLC Number:

R783.5

Hong Xinyu, Zhang Wenxuan, Qi Siyao, Yang Lan, Shen Wenxin, Liu Jian. Follow-up study evaluating morphological changes in alveolar bone in the maxillary anterior region after extraction retraction in adult patients treated with clear aligners on the basis of cone beam computed tomography data[J]. West China Journal of Stomatology, 2026, 44(1): 54-64.

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测量项目		T1	T2	T3	P值
测量项目		T1	T2	T3	T2和T1	T3和T2	T3和T1	Overall
上颌中切牙	LVBL	1.92±0.68	2.48±0.83	2.12±0.82	0.002^b*	0.012^b*	0.180^b	0.000^b*
	PVBL	1.51±0.56	2.27±0.71	1.81±0.58	0.000^b*	0.003^b*	0.636^b	0.000^b*
	MVBL	1.59±0.44	2.23±0.87	1.63±0.41	0.023^a*	0.056^a	1.000^a	0.032^a*
	DVBL	1.80±0.50	2.08±0.47	2.00±0.50	0.186^a	1.000^a	0.522^a	0.165^a
上颌侧切牙	LVBL	2.20±0.87	2.05±0.80	2.20±0.83	-	-	-	0.964^b
	PVBL	1.42±0.37	1.85±0.55	1.76±0.50	0.002^a*	1.000^a	0.005^a*	0.002^a*
	MVBL	1.73±0.61	2.14±0.58	2.01±0.64	0.000^b*	0.045^b*	0.045^b*	0.000^b*
	DVBL	2.24±0.55	2.26±0.66	2.15±0.63	-	-	-	0.218^b
上颌尖牙	LVBL	2.13±0.87	2.14±0.72	2.19±0.82	1.000^a	1.000^a	1.000^a	0.863^a
	PVBL	2.10±0.98	2.97±1.38	2.83±1.36	0.029^b*	1.000^b	0.043^b*	0.015^b*
	MVBL	1.68±0.84	2.06±0.77	2.01±0.57	0.001^b*	1.000^b	0.001^b*	0.000^b*
	DVBL	1.95±0.59	2.19±0.80	2.07±0.79	0.218^a	0.781^a	0.827^a	0.124^a

测量项目		T1	T2	T3	P值
测量项目		T1	T2	T3	T2和T1	T3和T2	T3和T1	Overall
上颌中切牙	LTBT1	1.00±0.47	1.27±0.80	1.37±0.75	0.054^a	1.000^a	0.030^a*	0.011^a
	LTBT2	0.92±0.21	1.47±0.45	1.46±0.64	0.000^b*	0.304^b	0.002^b*	0.000^b*
	LTBT3	1.06±0.32	1.68±0.76	1.60±0.85	0.011^b*	1.000^b	0.022^b*	0.005^b*
	PTBT1	1.20±0.44	1.03±0.53	1.29±0.56	-	-	-	0.134^b
	PTBT2	2.43±0.51	2.18±0.83	2.43±0.83	-	-	-	0.086^b
	PTBT3	4.06±1.03	4.60±1.45	4.52±1.47	0.652^a	1.000^a	0.870^a	0.066^a
	TBT1	8.44±0.38	8.90±0.66	9.00±0.70	0.015^a*	1.000^a	0.008^a*	0.001^a*
	TBT2	8.82±0.66	9.41±0.88	9.37±0.96	0.002^a*	1.000^a	0.002^a*	0.000^a
	TBT3	9.20±1.33	10.50±1.73	10.20±1.64	0.000^a*	0.089^a	0.000^a*	0.000^a*
上颌侧切牙	LTBT1	0.90±0.61	1.40±0.75	1.18±0.76	0.007^b*	0.066^b	0.221^b	0.007^b
	LTBT2	1.09±0.48	1.38±0.64	1.38±0.83	0.052^b	1.000^b	0.267^b	0.048^b*
	LTBT3	0.92±0.86	1.19±0.77	1.15±1.03	0.037^b*	0.055^b	1.000^b	0.423^b
	PTBT1	1.46±0.61	1.06±0.63	0.98±0.37	0.005^b*	1.000^b	0.002^b*	0.001^b
	PTBT2	2.61±1.23	1.99±1.05	1.92±0.91	0.014^a*	1.000^a	0.006^a*	0.003^a*
	PTBT3	4.17±2.05	3.97±2.00	3.85±1.98	-	-	-	0.935^b
	TBT1	8.17±0.91	8.13±0.90	7.95±0.75	-	-	-	0.368^b
	TBT2	8.74±1.60	8.31±1.25	8.24±1.04	-	-	-	0.576^b
	TBT3	8.88±2.18	8.91±2.01	8.69±2.04	-	-	-	0.340^b
上颌尖牙	LTBT1	1.00±0.55	1.19±0.70	1.16±0.73	0.064^a	1.000^a	0.246^a	0.054^a
	LTBT2	1.02±0.32	1.01±0.31	1.12±0.40	1.000^a	0.112^a	0.137^a	0.048^a*
	LTBT3	0.75±0.30	0.75±0.30	0.80±0.32	-	-	-	0.663^b
	PTBT1	1.11±0.59	0.58±0.54	0.54±0.48	0.003^b*	1.000^b	0.001^b*	0.000^b*
	PTBT2	2.26±0.72	1.81±0.76	1.66±0.63	0.007^b*	1.000^b	0.000^b*	0.000^b*
	PTBT3	3.95±1.26	3.29±0.94	3.16±0.95	0.005^a*	0.957^a	0.004^a*	0.004^a*
	TBT1	9.42±1.01	9.30±0.96	9.17±1.16	0.951^a	0.714^a	0.136^a	0.104^a
	TBT2	9.86±1.23	9.50±1.25	9.43±1.10	0.024^a*	1.000^a	0.017^a*	0.004^a*
	TBT3	10.12±1.36	9.46±1.35	9.41±1.35	0.001^a*	1.000^a	0.004^a*	0.002^a*

测量项目		T2-T1	T3-T2	r值	P值
上颌中切牙	LVBL	0.56±0.75	-0.36±0.58	-0.597^b	0.001*
	PVBL	0.76±0.70	-0.46±0.57	-0.407^b	0.039*
	MVBL	0.64±0.94	-0.60±1.01	-0.863^b	<0.001*
	DVBL	0.28±0.61	-0.08±0.70	-0.578^a	0.010*
上颌侧切牙	LVBL	-0.25±0.78	0.17±0.62	-0.254^a	0.200
	PVBL	0.43±0.60	-0.09±0.71	-0.691^a	<0.001*
	MVBL	0.41±0.55	-0.12±0.42	-0.142^a	0.472
	DVBL	0.03±0.57	-0.11±0.35	-0.154^a	0.433
上颌尖牙	LVBL	0.01±0.60	0.05±0.69	-0.598^a	<0.001*
	PVBL	0.87±1.50	-0.15±1.13	-0.298^a	0.110
	MVBL	0.38±0.49	-0.05±0.64	0.031^a	0.873
	DVBL	0.24±0.70	-0.12±0.55	-0.564^a	0.001*

测量项目		T2-T1	T3-T2	r值	P值
上颌中切牙	LTBT1	0.27±0.50	0.11±0.54	-0.378^b	0.100^b
	LTBT2	0.55±0.47	-0.01±0.40	0.043^a	0.856
	LTBT3	0.62±0.90	-0.08±0.53	0.078^b	0.751
	PTBT1	-0.30±0.32	0.29±0.44	-0.106^b	0.719
	PTBT2	-0.25±0.65	0.25±0.53	-0.558^a	0.011*
	PTBT3	0.54±0.91	-0.08±0.48	-0.409^a	0.082
	TBT1	0.45±0.64	0.10±0.50	-0.215^a	0.362
	TBT2	0.59±0.65	-0.04±0.52	-0.503^a	0.024*
	TBT3	1.30±1.09	-0.30±0.56	-0.720^a	0.001*
上颌侧切牙	LTBT1	0.50±0.76	-0.22±0.46	-0.254^a	0.202
	LTBT2	0.29±0.52	0.00±0.41	-0.175^a	0.384
	LTBT3	0.27±0.84	-0.04±0.60	-0.209^a	0.338
	PTBT1	-0.43±0.75	-0.08±0.68	-0.553^b	0.002*
	PTBT2	-0.62±1.30	-0.07±0.65	-0.446^b	0.015*
	PTBT3	-0.20±2.13	-0.12±0.87	-0.452^a	0.023*
	TBT1	-0.04±1.06	-0.18±0.72	-0.454^b	0.015*
	TBT2	-0.43±1.50	-0.08±0.74	-0.422^a	0.023*
	TBT3	-0.24±1.89	-0.22±0.98	-0.368^a	0.070
上颌尖牙	LTBT1	0.19±0.41	-0.03±0.42	-0.464^b	0.011*
	LTBT2	-0.01±0.26	0.11±0.29	-0.485^a	0.007*
	LTBT3	0.00±0.40	0.04±0.35	-0.331^a	0.074
	PTBT1	-0.53±0.81	0.04±0.55	-0.460^a	0.012*
	PTBT2	-0.45±0.81	0.16±0.53	-0.318^a	0.087
	PTBT3	-0.65±1.04	-0.13±0.73	-0.127^b	0.503
	TBT1	-0.12±0.64	-0.36±0.69	-0.471^a	0.009*
	TBT2	-0.36±0.70	0.66±0.88	-0.653^a	<0.001*
	TBT3	-0.66±0.88	-0.05±0.66	-0.045^a	0.814

测量项目	T2-T1	T3-T2	r1值	P1值	r2值	P2值
LVBL	0.56±0.75	-0.36±0.58	0.221^b	0.349	0.422^b	0.064
PVBL	0.76±0.70	-0.46±0.57	0.091^a	0.702	-0.160^a	0.500
MVBL	0.64±0.94	-0.60±1.01	-0.182^b	0.457	0.412^a	0.080
DVBL	0.28±0.61	-0.08±0.70	0.096^a	0.694	0.462^b	0.030*
LTBT1	0.27±0.50	0.11±0.54	-0.228^a	0.333	-0.299^b	0.201
LTBT2	0.55±0.47	-0.01±0.40	-0.350^a	0.130	-0.151^a	0.524
LTBT3	0.62±0.90	-0.08±0.53	-0.205^b	0.399	0.179^a	0.463
PTBT1	-0.30±0.32	0.29±0.44	-0.128^b	0.664	0.280^a	0.333
PTBT2	-0.25±0.65	0.25±0.53	0.294^a	0.208	-0.228^b	0.334
PTBT3	0.54±0.91	-0.08±0.48	0.682a	0.001*	0.005^a	0.983
TBT1	0.45±0.64	0.10±0.50	-0.333^a	0.152	0.314^a	0.178
TBT2	0.59±0.65	-0.04±0.52	0.060^a	0.801	-0.307^a	0.188
TBT3	1.30±1.09	-0.30±0.56	0.043^a	0.861	-0.109^a	0.657