中国组织工程研究 ›› 2013, Vol. 17 ›› Issue (41): 7255-7264.doi: 10.3969/j.issn.2095-4344.2013.41.011
• 口腔组织构建 oral tissue construction • 上一篇 下一篇
牙周膜牵引成骨快速远中移动尖牙的可行性
麦志辉1，张静兰2，卢红飞1，陈 奇1，梁焕友1，艾 虹1
- 1中山大学第三附属医院口腔科，广东省广州市 510630；2广东省口腔医院儿童牙科，广东省广州市 510280
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收稿日期:2013-03-30修回日期:2013-05-22出版日期:2013-10-08发布日期:2013-11-01 -
通讯作者:艾虹，硕士，教授，广东省口腔医院儿童牙科，广东省广州市 510280 Aih_zssy09@126.com -
作者简介:麦志辉☆，男，1977年生，广东省番禺市人，汉族，2012年中山大学毕业，博士，主治医师，主要从事口腔正畸学方面的研究。 并列第一作者：张静兰，硕士。 -
基金资助:广东省自然科学基金(s2011010004629)*
Rapid canine distal movement through distraction osteogenesis of the periodontal ligament
Mai Zhi-hui1, Zhang Jing-lan2, Lu Hong-fei1, Chen Qi1, Liang Huang-you1, Ai Hong1
- 1 Department of Stomatology, the Third Affiliated Hospital of Sun Yat-sen University, Guangzhou 510630, Guangdong Province, China;2 Department of Pediatric Dentistry, Guangdong Provincial Stomatological Hospital, Guangzhou 510280, Guangdong Province, China
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Received:2013-03-30Revised:2013-05-22Online:2013-10-08Published:2013-11-01 -
Contact:Ai Hong, Master, Professor, Department of Stomatology, the Third Affiliated Hospital of Sun Yat-sen University, Guangzhou 510630, Guangdong Province, China Aih_zssy09@126.com -
About author:Mai Zhi-hui☆, M.D., Attending physician, Department of Stomatology, the Third Affiliated Hospital of Sun Yat-sen University, Guangzhou 510630, Guangdong Province, China maiya2007@126.com Zhang Jing-lan, Master, Department of Pediatric Dentistry, Guangdong Provincial Stomatological Hospital, Guangzhou 510280, Guangdong Province, China Zhang Jing-lan and Mai Zhi-hui contributed equally to this paper. -
Supported by:Natural Science Foundation of Guangdong Province, No. s2011010004629*
摘要：
背景：牵引成骨应用于患者的尖牙远中移动，能大幅度提高牙齿的移动速度，同时保护磨牙支抗。但关于牵引的速率、尖牙的牙髓活力、尖牙的牙周组织改建及该技术的生物学机制目前研究甚少。 目的：在成人患者中，评估使用牙周膜牵张成骨快速远中移动尖牙的可行性，同时监测牙髓活力、牙根吸收及尖牙牙周组织改建情况。 方法：选取9例成年错牙合患者，拔除上颌两侧第一双尖牙，通过改良牵张装置快速远中移动尖牙至预定的位置。利用头颅定位片及根尖片测量尖牙远中移动距离、支抗丧失、根尖吸收及牙槽间隔改建情况；并监测尖牙的牙髓及牙周情况。 结果与结论：通过牙周膜牵张成骨能在12-16 d内快速远中移动上颌尖牙至预定位置，尖牙远中移动7.18 mm 及远中倾斜(13.24±2.87)°；支抗丧失为0.5 mm；未见明显根尖吸收及牙周组织丧失；尖牙的牙髓活力在牵引后迅速下降，但3个月后明显恢复。结果显示牙周膜牵引成骨可显著加快尖牙移动速度，缩短矫治时间，同时保护磨牙支抗；未见牙根明显吸收、牙齿松动、牙髓坏死及牙周组织丧失等不良反应。提示牙周膜牵引成骨能够快速有效移动尖牙。
中图分类号:
引用本文
麦志辉，张静兰，卢红飞，陈 奇，梁焕友，艾 虹. 牙周膜牵引成骨快速远中移动尖牙的可行性[J]. 中国组织工程研究, 2013, 17(41): 7255-7264.
Mai Zhi-hui, Zhang Jing-lan, Lu Hong-fei, Chen Qi, Liang Huang-you, Ai Hong. Rapid canine distal movement through distraction osteogenesis of the periodontal ligament[J]. Chinese Journal of Tissue Engineering Research, 2013, 17(41): 7255-7264.
General situation of experimental subjects
Root resorption
Three months after placement of fixed appliance (Figure 4G), the width of periodontal space of canine returned to normal, with a clear lamina dura. The height of interval alveolar bone returned to the level before distraction; while the density of neonatal mesial interval alveolar bone was slightly lower (Figure 5).
Pulp vitality of maxillary canines, second premolar and first molar
Canine periodontal situation There were significant differences in canine periodontal probing depth and mucogingianl junction width between T1, T2 and T3. During canine distration, the periodontal tissue was healthy without edema and inflammation. Oral ulcers were found in three patients because of the oppression on the mucosa by the distraction device (Table 3).
Model measurement
After 12-16 days, mean (4.0±1.8) days of distraction, the canines moved to the expected position in all cases. The patients only felt mild discomfort during activation of the distraction device, a little tense in the canine area, but the symptoms disappeared after 10-15 minutes. No hot and cold stimulated pain or spontaneous pain happened. Oral ulcers were found in three patients because of the oppression on the mucosa by the distraction device. There were no difficulties in activating the distraction device. No loosening and falling off of distraction device happened.
Tooth looseness of canine
When the distraction was completed, 4/18 of maxillary canines had looseness of angle class Ⅱ, 14/18 of maxillary canines had looseness of angle classⅠ. One month after placement of fixed appliance, all canines had looseness of angle classⅠ. There was no looseness of maxillary first molar and second premolar.
Cephalometric analysis(Table 1)
After canine distraction, the amount of canine retraction achieved was an average of 7.18 mm, at a rate of 0.5 mm per day. The distal tipping of canine was (13.24 ±2.87)° at T2, but it reduced to (6.43±1.14)° at T3. The mean sagittal (U6m-Y) and vertical (U6m-X) anchorage loss was 0.5 mm and 0.2 mm at T2, and was 0.8 mm and 0.4 mm at T3, respectively. No signi?cant changes were observed in the other measurements (Table 1).
Root resorption
Root resorption of the canines was minimal. After distraction, apical root resorption of S1 occurred in 2/18 of the canines, while rdiographic examination showed no evidence of complications, such as root fracture and ankylosis in all teeth (canines, incisors, second premolars, ?rst molars), in any patient. No apical or lateral root resorption (S0) was detected in any subject at T1, T2 and T3.
Remodeling of the canine periodontal tissues
Newly formed alveolar bone in mesial canines was matured at 3 months after distraction. The periapical radiographs showed a process from empty to solid in the mesial distraction space of canine. One week after canine distraction (Figure 4C), the mesial periodontal space was widened (the space of cervical area was wider than the apical area), showing low density, and the original lamina dura turned indistinct, while the distal lamina dura remained clear. The alveolar fossa was significantly narrowed because of pressure and showed no significant increase of density. No obvious fracture line was found in distal alveolar bone of canine.
At the end of the canine distraction (Figure 4E), the mesial periodontal space of canine became obvious, with a triangle-shaped opening towards the gingival margin. The lamina dura was invisible. Low-density was showed in the apical area of canine. Distal periodontal space was widened and the lamina dura disappeared. The alveolar fossa was significantly narrower than before, but the boundary was still clear. The density of alveolar fossa was higher than that in the first week of distraction. Obvious deformation caused by pressure was found in the distal interval alveolar bone of the canine. The boundary of the alveolar crest was indistinct, and the height of it was decreased by about 1 mm. A low-density shadow was found in the lower 1/3 of the interval alveolar bone, which was considered to be a fracture line.
One month after placement of fixed appliance (Figure 4F), the mesial space of canine was still empty, but the density was higher than that in the first two weeks. The density around the canine root was significantly increased, but no obvious formation of lamina dura was found. The boundary of alveolar fossa was still indistinct. The density of alveolar fossa was high, but still lower than normal. The periodontal space of canine was still clear. Oblique resorption was found in the alveolar crest, and the height of it was decreased by about 1.5 mm.
Pulp vitality of maxillary canines, second premolar and first molar
At T2, 2/18 of the canines were in a state of shock, decline of pulp vitality appeared in 16/18 of the canines and it had significant differences with that of T1 (P < 0.05). Three months after the fixed appliance treatment, the canine pulp vitality recovered partly and had no significant differences with that of T1 (P > 0.05). The second premolar and first molar had no pulp vitality change (Table 2).
Canine periodontal situation There were significant differences in canine periodontal probing depth and mucogingianl junction width between T1, T2 and T3. During canine distration, the periodontal tissue was healthy without edema and inflammation. Oral ulcers were found in three patients because of the oppression on the mucosa by the distraction device (Table 3).
Model measurement
After canine distraction, the measurements of 6-6/perimeter, 6-6/width, and 6-6/width of base bone had no significant difference (P > 0.05). There were sigfniciant differences in the measurements of 3-6/distance, 2-6/distance, and 3-3/width before and after canine distraction (P < 0.05). Three months after placement of fixed appliance, there were no significant differences in the measurements of 6-6/width, and 6-6/width of base bone before and after canine distraction (P > 0.05), whereas the measurements of 6-6/perimeter, 3-6/distance, 2-6/distance, and 3-3/width of base bone had significant difference from those before distraction (P < 0.05), and the measurements of 3-3/width had significant difference from those before and after distraction (P < 0.05) (Table 4).
| [1] Codivilla A. The classic: On the means of lengthening, in the lower limbs, the muscles and tissues which are shortened through deformity. 1905. Clin Orthop Relat Res. 2008;466(12):2903-2909.
[2] Ilizarov GA. The principles of the Ilizarov method. Bull Hosp Jt Dis Orthop Inst. 1988;48(1):1-11.
[3] McCarthy JG. The role of distraction osteogenesis in the reconstruction of the mandible in unilateral craniofacial microsomia. Clin Plast Surg. 1994;21(4):625-631.
[4] Liou EJ, Huang CS. Rapid canine retraction through distraction of the periodontal ligament. Am J Orthod Dentofacial Orthop. 1998;114(4):372-382.
[5] Sharpe W, Reed B, Subtelny JD, et al. Orthodontic relapse, apical root resorption, and crestal alveolar bone levels. Am J Orthod Dentofacial Orthop. 1987;91(3):252-258.
[6] von Böhl M, Maltha JC, Von Den Hoff JW, et al. Focal hyalinization during experimental tooth movement in beagle dogs. Am J Orthod Dentofacial Orthop. 2004;125(5): 615-623.
[7] von Böhl M, Kuijpers-Jagtman AM. Hyalinization during orthodontic tooth movement: a systematic review on tissue reactions. Eur J Orthod. 2009;31(1):30-36.
[8] Kim SJ, Park YG, Kang SG. Effects of Corticision on paradental remodeling in orthodontic tooth movement. Angle Orthod. 2009;79(2):284-291.
[9] Chung KR, Mitsugi M, Lee BS, et al. Speedy surgical orthodontic treatment with skeletal anchorage in adults--sagittal correction and open bite correction. J Oral Maxillofac Surg. 2009;67(10):2130-2148.
[10] Ghoneima AA, Allam ES, Zunt SL, et al. Bisphosphonates treatment and orthodontic considerations. Orthod Craniofac Res. 2010;13(1):1-10.
[11] Ahn JJ, Shin HI. Bone tissue formation in extraction sockets from sites with advanced periodontal disease: a histomorphometric study in humans. Int J Oral Maxillofac Implants. 2008;23(6):1133-1138.
[12] Prabhakar AR, Tauro DP, Shubha AB. Management of an unusual maxillary dentoalveolar fracture: a case report. J Dent Child (Chic). 2006;73(2):112-115.
[13] Brusveen EM, Brudvik P, Bøe OE, et al. Apical root resorption of incisors after orthodontic treatment of impacted maxillary canines: a radiographic study. Am J Orthod Dentofacial Orthop. 2012;141(4):427-435.
[14] Weltman B, Vig KW, Fields HW, et al. Root resorption associated with orthodontic tooth movement: a systematic review. Am J Orthod Dentofacial Orthop. 2010;137(4):462-476; discussion 12A.
[15] Cope JB, Harper RP, Samchukov ML. Experimental tooth movement through regenerate alveolar bone: A pilot study. Am J Orthod Dentofacial Orthop. 1999;116(5):501-505.
[16] Nakamoto N, Nagasaka H, Daimaruya T, et al. Experimental tooth movement through mature and immature bone regenerates after distraction osteogenesis in dogs. Am J Orthod Dentofacial Orthop. 2002;121(4):385-395.
[17] Kharkar VR, Kotrashetti SM. Transport dentoalveolar distraction osteogenesis-assisted rapid orthodontic canine retraction. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2010;109(5):687-693.
[18] Kumar PS, Saxena R, Patil S, et al. Clinical investigation of periodontal ligament distraction osteogenesis for rapid orthodontic canine retraction. Aust Orthod J. 2009;25(2):147-152.
[19] Gürgan CA, I?eri H, Ki?ni?ci R. Alterations in gingival dimensions following rapid canine retraction using dentoalveolar distraction osteogenesis. Eur J Orthod. 2005;27(4):324-332.
[20] Ren Y, Maltha JC, Kuijpers-Jagtman AM. Optimum force magnitude for orthodontic tooth movement: a systematic literature review. Angle Orthod. 2003;73(1):86-92.
[21] Alkumru P, Erdem D, Altug-Atac AT. Evaluation of changes in the vertical facial dimension with different anchorage systems in extraction and non-extraction subjects treated by Begg fixed appliances: A retrospective study. Eur J Orthod. 2007;29(5):508-516.
[22] Sayin S, Bengi AO, Gürton AU, et al. Rapid canine distalization using distraction of the periodontal ligament: a preliminary clinical validation of the original technique. Angle Orthod. 2004;74(3):304-315.
[23] Tanne K, Yoshida S, Kawata T, et al. An evaluation of the biomechanical response of the tooth and periodontium to orthodontic forces in adolescent and adult subjects. Br J Orthod. 1998;25(2):109-115.
[24] Yoshihara T, Matsumoto Y, Suzuki J, et al. Effect of serial extraction alone on crowding: spontaneous changes in dentition after serial extraction. Am J Orthod Dentofacial Orthop. 2000;118(6):611-616.
[25] Wei S, Fu MK. Posttreatment stability of four first bicuspid extraction cases treated with the Alexander technique--model analysis. Zhonghua Kou Qiang Yi Xue Za Zhi. 2005;40(4):271-274.
[26] Miyajima K, Nakamura S. Distalization with 'driftodontics'. J Clin Orthod. 1994;28(7):393-394.
[27] Miura H, Hasegawa S, Okada D, et al. The measurement of physiological tooth displacement in function. J Med Dent Sci. 1998;45(2):103-115.
[28] Gritsch K, Laroche N, Morgon L, et al. A systematic review of methods for tissue analysis in animal studies on orthodontic mini-implants. Orthod Craniofac Res. 2012; 15(3):135-147.
[29] Ai H, Xu QF, Lu HF, et al. Rapid tooth movement through distraction osteogenesis of the periodontal ligament in dogs. Chin Med J (Engl). 2008;121(5):455-462.
[30] Kharkar VR, Kotrashetti SM. Transport dentoalveolar distraction osteogenesis-assisted rapid orthodontic canine retraction. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2010;109(5):687-693.
[31] Kurt G, I?eri H, Ki?ni?ci R. Rapid tooth movement and orthodontic treatment using dentoalveolar distraction (DAD). Long-term (5 years) follow-up of a Class II case. Angle Orthod. 2010;80(3):597-606.
[32] Ding Y, Liu Y, Cao M, et al. Periodontal tissues changes in tooth-borne distraction osteogenesis: an experimental study of closure of wide alveolar bone defects in dogs. Br J Oral Maxillofac Surg. 2009;47(2):111-115.
[33] Thiruvenkatachari B, Pavithranand A, Rajasigamani K, et al. Comparison and measurement of the amount of anchorage loss of the molars with and without the use of implant anchorage during canine retraction. Am J Orthod Dentofacial Orthop. 2006;129(4):551-554. |
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Distraction osteogenesis was used as early as 1905 by Codivilla[1] and was later popularized by the clinical and research studies of Ilizarov[2]. Recently, distraction osteogenesis has been extensively applied to the correction of craniofacial deformities[3] and is becoming a viable treatment option in the canine retraction[4], which can greatly increase the speed of the canine retraction, while protecting the molar anchorage. This technique is considered to be a breakthrough in orthodontics.
When the tooth is gradually distalized into the extraction socket, the periodontal ligament generates new bone in a direction parallel to the tooth movement, which is similar to the tooth movement. But little is known about canine pulp vitality, and periodontal tissue reconstruction, as well as the biological mechanism in adult patients. This study is to address these questions, aiming at providing further reference for clinical application of this technique.
Canine retraction, with traditional orthodontic treatment techniques, usually lasts for 6 to 8 months, and at the same time, extraoral or intraoral anchorage devices are required to maintain the space of extraction. Therefore, conventional treatment with ?xed appliances is likely to last about 2 years. The duration of orthodontic treatment is one of the things that orthodontic patients complain about most, especially the adult patients. A novel method of reducing the time and the anchorage demands during canine movement is by using the principles of distraction osteogenesis[4], by weakening the interseptal bone distal to canine and distracting the periodontal ligament through a custom made intraoral distraction device.
When the tooth is gradually distalized into the extraction socket, the periodontal ligament generates new bone in a direction parallel to the tooth movement, which is similar to the tooth movement. But little is known about canine pulp vitality, and periodontal tissue reconstruction, as well as the biological mechanism in adult patients. This study is to address these questions, aiming at providing further reference for clinical application of this technique.
Design
An clinical prospective studies.
Time and setting
This study was performed in the Department of Stomatology, the Third Affiliated Hospital of Sun Yat-sen University from October 2006 to May 2007.
Subjects
Nine patients, aged 21-26 years old, averaged (24.2±1.9) years, 3 males and 6 females, who had the first visit to our department from October 2006 to December 2006, were selected in this study. The inclusion criteria were as follows[4]: angle classⅡ malocclusion, while extraction treatment of bilateral maxillary first premolar and absolutely strong molar anchorage are needed; no defection, pulp, periodontal or periapical lesions can be found on bilateral maxillary canine and first premolar; no obvious sign of labial and palatal dislocation of the maxillary canines; with good oral hygiene habits and a good compliance; no systemic diseases, like cardiopathy and glycuresis. The exclusion criteria were: non-extraction case; maxillary canines and first molar had defection, pulp, periodontal or periapical lesions; maxillary canines dislocated labially or palatally; patient had systemic diseases, like cardiopathy and glycuresis.
All patients were informed before the surgery of the postoperative complications and further measures to correct them, and the informed consents were signed. This research project was approved by the ethics committee at the Third Affiliated Hospital of Sun Yat-sen University (China). All patients were carried out maxirally canine retraction through distraction osteogenesis of periodontal ligament using custom-made tooth-borne intraoral devices.
Methods
X-cephalometry
Cephalometric photoes were taken at T1, T2 and T3, and analyzed using the software Nemotec Analysis. All the marked points were decided by three orthodontic doctors by consensus. Reference planes and the items are shown in Figure 1.
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Periapical film examination
Periapical radiographs of the maxillary canine and first premolar were taken and measured for the following parameters: canine and first premolar root length (take tooth cusp and apex as marked points); periapical distance between first premolar and canine; interval widths between canine and first premolar at the top of alveolar ridge, in the middle and root apex; the root width of first premolar at enamelo-cemental junction and in the middle of root.
Individual bands of maxillary canine and first molar were prepared, and the impressions were taken. The bands were put inside the impression and the plaster models were then made.
Tooth extraction and alveolar bone trimming
Following conventional local anesthesia and disinfection, bilateral maxillary first premolars were extracted. Their root length and width were measured, then the actual vertical distance between first premolar and canine root apex and the actual width of alveolar bone between them generated. ITI dental implant spherical drill was used for alveolar bone trimming (Figure 2), which made the depth of first premolar alveolar fossa down to the level of canine root apex or 0.5 mm more. Half of the canine distal interval alveolar bone was removed by grinding. The buccolingual lateral and periapical groove was prepared. Normal saline of 4 ℃ was used for cooling during the operation. No gelfoam was placed inside the alveolar fossa.
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Activation of the distraction device
A custom-made tooth-borne intraoral device, which consisted of a sliding screw and a sliding rod that soldered to the bands for the canine and the first molar, and the sliding rod placed as apically as possible to minimize tipping (Figure 3). The device was activated twice immediately after the alveolar bone trimming (screw 180°), and then activated twice per day, with each time retracting for 0.25 mm (screw 90°). The activation frequency of the distraction device was adjusted based on actual canine mobility in the follow-up visits, if necessary.
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The distraction device was consolidated for 2 weeks when the canine had moved to the expected position. And then, ?xed orthodontic appliance treatment was started, and the canine was uprighted. Ligatures were placed between the canine and the ?rst molar and kept for 3 months.
Tooth looseness testing
The looseness of maxillary canine, second premolar and first molar was checked right after the removal of the distraction device, 1 and 3 months after the placement of the fixed appliance (in accordance with standards of clinical tooth looseness division).
Pulp vitality testing
Pulp vitality was evaluated and recorded with an electronic digital pulp tester (Satelec-Pierre Rolland, France) at T1 (canine retraction completion), T2 (consolidation) and T3 (3 months after fixed appliance treatment). All teeth (canines, incisors, second premolars and ?rst molars) subjected to pulp vitality test were cleaned. The probe was placed on the incisal one-third of the buccal surface, and the current was increased gradually to observe for sensation.
Periodontal status of the canine
The depth of periodontal pocket of canine was measured with periodontal probe (Yinxing, Guangzhou, China) at T1, T2 and T3 at the following six points: mesiobuccal, centrobuccal, distobuccal, mesiopalatal, centropalatal, and distopalatal (accurate to 0.5 mm). The width of the canine buccal gingiva was also measured (accurate to 0.5 mm).
Periapical radiographs
Periapical radiographs of the canine and first premolar were taken at T1, T2 and T3, before and right after the alveolar bone trimming. The photos were enlarged 8 times for evaluation of root resorption, based on Sharpe root resorption grading criteria[5], as follows: S0=no apical root resorption; S1=widening of periodontal ligament space at the root apex; S2=moderate blunting of the root apex (up to one third of the root length); S3=severe blunting of the root apex (beyond one third of the root length).
Model measurement
The impression was taken and the plaster model was made at T1, T2 and T3. The items of model measurement were 6-6/perimeter, 6-6/width, 6-6/width of base bone, 3-6/distance, 2-6/distance, 3-3/width and 3-3/width of base bone.
Main outcome measures
The following parameters were measured: the displacement distance, root resorption and probing depth of canine; the tooth looseness and pulp vitality of canine, first premolar and first molar; the width of canine-canine and first molar-first molar on model.
Statistical analysis
All data were analyzed using the software SPSS 11.0, paired t test was used for comparison between two groups, and analysis of variance, least significant difference, and Student-Newman-Keuls analysis were used for comparison among multiple groups.
The mechanism of rapid tooth movement
Tooth movement is a complex biomechanical process. Under mechanical force, bone resorption appears at pressure side, and deposition appears at tension side, then alveolar bone is remodelling, which then results in tooth movement. Therefore, rapid tooth movement requires not only acceleration of bone resorption, but also acceleration of bone deposition, that is acceleration of alveolar bone remodelling. In traditional treatment, there is a stagnant period of tooth movement[6], and during this period of time, tooth does not move or move at a low speed. The majority of researchers believe that tooth has a physical contact with alveolar bone under mechanical force, which causes partial necrosis of periodontal ligament and cell-free hyaline degeneration in tissue[7]. Tooth movement requires clearance of the hyalinized tissue. Osteoclasts, which absorb the hyalinized tissue, have to migrate from the latent-de-sac resorption area to periodontal ligament, so tooth movement is slow at this stage. The hyalinized tissue of human usually sustains for 2-3 weeks, depending on age of patients, density of alveolar bone, and extension of hyaline degeneration of periodontal ligament[8]. Stagnant period is equivalent to the time required for resorption of the hyalinized tissue.
Many authors think that alveolar bone bending is another mechanism of tooth movement. According to Chung’s study[9], alveolar bone bending can effectly accelerate tooth movement. Ashcraft’s studies[10] showed that the lower density of interval alveolar bone means the smaller resistance, and the sooner tooth movement. Therefore, in this experiment, the drag-reducing measures play an important role in rapid tooth movement. Generally, alveolar fossa will be imbued with regenerated bone tissue at 3 weeks after extraction, new bone area exceeded 50% of socket in 8 weeks[11]. So the best way to take full advantage of extraction space is to let tooth movement complete within 3 weeks. The only resistance during tooth movement is distal alveolar bone of canine, so chiseling away some of distal alveolar bone to form a bone fossa will obviously decrease bone resistance, while preserving the integrity of periodontal ligament. Decreasing of bone resistance plays an important role in distraction osteogenesis of periodontal ligament. Certain thickness of distal alveolar bone should be preserved to protect periodontal ligament of canine, which can also provide blood supply, and thus ensuring the tooth movement to be a healthy and stable process. Though, the distal alveolar bone will be absorbed and then regenerated eventually, complete removal of alveolar bone may lead to ankylosed root or root resorption[12]. Preservation of 0.5-1 mm distal alveolar bone has achieved good effect in this study.
Improvement of distraction device
The distraction devices have been modified and adjusted for optimum parallel canine movement as follows: a certain width of bands is preserved to increase the contact area with teeth; connecting rods are welded on distal side of bands to reduce canine rotation; connecting rods are welded vertically; the guidance bar was placed near root apex. The results have revealed a controlled distal inclination of (13.24±2.87)° of the canines, without canine rotation or fall off of distraction device.
Root resorption
It is commonly believed that root resorption occurs during orthodontic process. Root resorption has been found to be related to many factors including orthodontic force, time, age, sex, individual sensitivity, etc. The duration of orthodontic force is more important than its magnitude[13]. Root resorption occurs 2-3 months after fixed orthodontic application and continues throughout entire course[14], so tooth movement should be completed before root resorption starts. Periapical radiographs in our study showed no obvious root resorption in canines and lateral incisors after 3 months of distraction. Animal studies by Cope et al [15] and Nakamoto et al [16] found that serious root resorption can occur on the compressive side if orthodontic force is larger than 50 g, which could be up to 1/2 of dentin thickness. Greater orthodontic force and longer duration means more severe root resorption.
Pulp vitality of canines
There are various methods to test the pulp vitality, such as electric pulp vitality test, temperature experiment, laser Doppler flow measurement, dual-wavelength spectrophotometry, photoelectric plethysmography, Pulse Oximetry and so on. In this study, electric pulp vitality tests showed that pulp vitality of canine decreased significantly at T2, and partially recovered at T3, and had significant difference from that at T1 (P < 0.05). Our findings are similar to Liou and Huang’s clinical studies[4]. The pulp vitality test may not always be reliable because of the orthodontic force. No clinical symptoms or signs of pulpitis or pulp necrosis by periapical radiography were observed in our study. The animal experiment by Liou et al[4] also showed that the teeth can still maintain normal pulp vitality while moving 1.2 mm per week. Similarly, Kharkar et al [17] and Kumar et al [18] showed that there was no pulp vitality deterioration in canine after rapid canine retraction thought periodontal ligament distraction osteogenesis.
Periodontal remodeling of canine
The results showed that the distal periodontal pocket of canine was 0.5-0.7 mm at T2 and had no significant difference when compared with T1 (P > 0.05). Three months after placement of fixed appliance, the distal periodontal pocket depth was lower. This might be related with bone trimming and rapid alveolar bone remodeling during distraction. However, clinical study by Gürgan et al [19] showed that the canine periodontal pocket depth was more than 4 mm after distraction and had significant difference when compared with that before distraction, which is probably due to the canine flap surgery after bone trimming.
Tipping of canine
There are three possible moving manners of teeth in extraction fossa: free tipping movement, that is, crown moves towards extraction zone, while root moves towards reverse side; controlled tipping movement, that is, root stands still, while crown moves towards extraction zone; parallel movement, that is, crown and root move to the same direction. Tipping movement is considered to be the safest way because it is the main way of natural tooth movement[20]. Begg technology is characterized by two steps of tooth movement[21], which are crown tipping and then root uprighting. The resistance center on single-rooted teeth is located at apical 1/3. When orthodontic force was imposed near the center, body movement can be attained. In this study, in order to attain body movement as much as possible, connecting rod was adjusted to close as possible to the resistance center. However, tipping movement still occurred. But the inclination was less than 20°, which is similar to other studies. In Sayin’s study[22], the distraction devices were activated 0.5 mm per day and the maxillary canines had a distal inclination of 11.47°, while the mandibular canines tippinged 7.16°. But in Codivilla study[1], the distraction devices were activated 0.75 mm per day, and the canines had a distal inclination of 17°. In this study, when the distractions were finished, cusp of canine moved distal for (7.18±1.3) mm, apical point of canine moved (1.15±0.9) mm, and the canines had a distal inclination of (13.24±2.87)°. That means canine movement was mainly controlled tipping. The measurement is slightly greater than other studies[1] which may probably be because: the removal of canine periapical bone resistance was inadequate because of the existence of maxillary sinus; bone density and bone resistance are higher in Asian population; the design of distraction device may have defects, for example, the connection of the screw to nut is not tight. Three months after fixed appliance, canines had a distal inclination of (6.43±0.14)°, which basically expressed the preplaced distal angle of MBT Bracket (17°).
Model measurements showed that at T2, 3-3/width and 3-3/base bone degrees has an increase of (11.5±1.0) mm and (6.9±0.1) mm, respectively, which indiates that there is not only canine distal tipping, but also buccal tipping. That may probably be because: the traction device is on buccal side; the canine alveolar bone is thinner on buccal side and has smaller resistance; the first molar is more laterally than canine. Three month after fixed appliance, the 3-3/width:6-6/width is 0.93, indicating that the canine has been fully integrated into dental arch. This study showed that it takes about 3 months for canine upright, indicating that it only needs 4 months for canine body to move to the ideal location, which will take 6-8 months in conventional method. Orthodontic during by periodontal ligament distraction osteogenesis can significantly shorten for 3-6 months, but the tipping canine movement using traction remains to be further studied.
Incisor self-drifting
Tooth self-drift was first proposed by Tanne et al[23]. Yoshihara et al[24] believed that tooth self-drift plays important role in alleviating anterior teeth crowding in serial extraction. Wei et al [25] strongly supports this theory, and has also applied it to lower arch correction. The model measurements in our study showed that at 1 month after canine traction, bilateral maxillary lateral incisor self-drifted distally for 1.3 mm, which may greatly alleviate anterior teeth crowding due to loss of canines support, low resistance of traction gap, the fibers traction between canine and incisor[26], and synergy of labial muscle[27].
Anchorage loss
Anchorage is a very important factor in orthodontic treatment. Any force imposed on tooth for correction will generate a counter force, and support of this counter force is known as anchorage[28], which may also be defined as “the resistance of tooth movement after applied force”. Previous studies[17] have indicated that the periodontal membrane compression caused by a light or heavy orthodontic force will make tooth move a small distance (0.3-0.7 mm), after that, tooth still stay for 2-3 weeks, which is called stagnant period of orthodontic tooth movement. In our animal study, the loss of anchorage was smaller than 0.5 mm in rapid tooth retraction groups[29]. Clinical studies show that the anchorage tooth moves mesially for 0.6 mm after canine retraction, and 0.7 mm at T3, which was consistent with other researchs[4, 30-32]. In conventional methods for canine retraction, the molar anchorage loss is 1.6 mm on average[33]. Distraction osteogenesis of the periodontal ligament has been shown to be able to prevent molar anchorage loss due to stagnant period of tooth movement.
Clinical significance of rapid canine retraction
(1) Rapid canine distal movement: our clinical results showed that canine moves 0.5-0.8 mm per day during distraction, which is much better than conventional methods (canine moves about 1 mm per month).
(2) Protection molar anchorage: molar anchorage loss is less than 0.5 mm at canine retraction, and less than 0.8 mm at canine uprighting.
(3) Incisor self-drift: lateral incisors move distally for about 1.3 mm, which greatly alleviates anterior crowding.
(4) Shorten treatment time: it took 4 months for canine distraction and uprighting.
Distraction osteogenesis for rapid canine retraction is a promising and feasible for clinical practice. With this technique, rapid tooth movement and less anchorage loss can be easily achieved.
1通过改良的牵引装置，快速远中移动上颌尖牙，同时监测牙髓活力、牙根吸收及尖牙牙周组织改建情况，为临床推广该技术提供依据。 2国内首次应用牙周膜牵引成骨技术移动尖牙，较为系统评估牙周膜牵引成骨技术快速远中移动尖牙的临床可行性，评估手段较为全面，临床意义较大。
牵引成骨是一项通过将骨切开后应用牵引装置缓慢牵拉，使截骨间隙中形成新骨，从而达到骨骼延长目的的技术。该项技术由前苏联著名骨科教授Ilizarov发明，最初被用于矫正肢体长度不等，文献上也称骨牵引、骨痂成形、骨痂牵引、骨延长等。虽然这一技术最初应用于下肢骨，但这些来自肢骨牵引的许多经验如今已被成功地用于颅面骨畸形的矫治，对患者开始治疗的时间也可提前至幼儿时期。与传统的治疗方法如骨切开自体骨移植、异体骨移植、生物材料种植等相比，具有手术创伤小、继发病变少、无需植骨、牵引骨周围软组织可以同时得到扩张等优点，因而该项技术对颅面畸形的矫治具有很大的潜力和广阔的应用前景。牵引成骨通常分为4个阶段：①骨切开。②间歇期。③牵引期和④固定期。影响牵引成骨期间牵引区新骨形成的质量取决于骨段固定的坚固程度、骨髓及骨周软组织和血供受损伤的程度、牵引的速度和频率、新骨负重前适当钙化改建期，而截骨线和牵引力的方向，决定了新骨形成的方向和形态。
牵引成骨在颅颌面外科应用的适应证：半侧颜面发育不全畸形，颞下颌关节强直引起的小下颌畸形，小下颌畸形伴阻塞性睡眠呼吸暂停低通气综合征、颌骨缺失的牵引成骨重建，颌骨部分缺损或牙槽骨缺损的垂直向牵引成骨，移植骨的牵引成骨，上下牙弓狭窄的扩弓治疗，腭裂继发重度上颌后缩畸形牵引成骨矫治和颅面部重度发育不全的牵引成骨前徙，如Crouzon综合征、Apert综合征等。另外，利用该技术，还可以修复外伤或肿瘤术后的颌骨缺损，恢复牙槽骨高度，为牙种植手术创造条件。
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