钛合金/不锈钢微植体支抗稳定性的组织学研究

目的:评估钛合金和不锈钢微植体支抗即刻负载的稳定性。方法:选用8只本地成年雄性犬,每只犬任选一侧上颌骨和对侧下颌骨各植入1枚钛合金和不锈钢微植体。同颌2枚微植体间即刻加载1.96 N的力。4周和12周时各随机处死4只实验犬,制作硬组织切片进行组织学研究。结果:所有微植体均没有松动、脱落。微植体与周围组织有良好的生物相容性,种植体周围有纤维组织和骨组织共同包绕。骨结合率随着愈合时间的延长而增高,钛合金微植体骨结合率高于不锈钢微植体。结论:即刻负载下,钛合金和不锈钢微植体支抗的愈合形式都是纤维骨性结合,均可保持稳定,钛合金微植体更为稳定。     

Patients' perceptions regarding microimplant as anchorage in orthodontics

OBJECTIVE: To determine patients' expectations, acceptance, and experience of pain with microimplant surgery compared to other orthodontic procedures. MATERIALS AND METHODS: Seventy-eight microimplants were placed in 37 patients as an anchorage unit for orthodontic treatment. Patients were asked to rate anticipated pain and pain experienced with various orthodontic procedures (tooth extraction, insertion of separators, initial tooth alignment, and microimplant surgery) on a visual analog scale (VAS) over a 7-day period. One month after insertion of microimplants, patients were asked to rate their acceptance of the procedure using a structured questionnaire. RESULTS: Unlike other orthodontic procedures, patients expected to experience a significantly higher level of pain with microimplant surgery than they experienced (P < .001). The postoperative pain experienced decreased continuously from day 1 to day 7 for all orthodontic procedures (P < .05). The total area under the curve (AUC) of pain experienced over the 7-day period was significantly larger for initial tooth alignment than for microimplant surgery (P < .05). Most patients were satisfied with the microimplant surgery (76%) and would recommend it to a friend or family member (78%). CONCLUSIONS: Patients tended to overestimate the pain anticipated with microimplant surgery. Patients were accepting of the surgery and would recommend it to others.     

The perception of pain following interdental microimplant treatment for skeletal anchorage: a retrospective study

During orthodontic therapy, patients frequently complain about pain and discomfort, especially during insertion of fixed appliances. Skeletal anchorage using an interdental microimplant is a new concept in orthodontic treatment. The purpose of this study was to investigate differences and changes in the level of pain among patients in relation to orthodontic microimplant treatments. Forty microimplants were applied to the maxilla as skeletal anchors in the orthodontic treatment. The visual analog scale (VAS) was used to evaluate the patients’ perception of pain during this new modality treatment. The premolar extraction VAS core was used as a baseline for the complete orthodontic procedure. The mean VAS score was 35.8 mm at 24 h after premolar extraction. The mean VAS score for insertion and removal of the microimplant 24 h after the operation was 12.3 and 7.8 mm, respectively. Three months after removal of the skeletal anchors, the VAS score had decreased to 3.2 mm and was the same as with the traditional orthodontic treatment. By using the repeated-measure general linear model (GLM), we found that the score 1 day after microimplant placement was significantly less than that 1 day after first premolar extraction or that 1 day after fixed appliance insertion. This result indicates that interdental microimplant did not generate any greater pain than other orthodontic procedures. Therefore, patients were willing to adopt the new orthodontic treatment.     

Optimal force magnitude loaded to orthodontic microimplants: A finite element analysis

Objective:To find an optimal force that can be loaded onto an orthodontic microimplant to fulfill the biomechanical demands of orthodontic treatment without diminishing the stability of the microimplant.Materials and Methods:Using the finite element analysis method, 3-D computer-aided design models of a microimplant and four cylindrical bone pieces (incorporating cortical bone thicknesses of 0.5, 1.2, 2.0, and 3.0 mm) into which the microimplant was inserted were used. Various force magnitudes of 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, and 4.0 N were then horizontally and separately applied to the microimplant head as inserted into the different bone assemblies. For each bone/force assembly tested, peak stresses developed at areas of intimate contact with the microimplant along the force direction were then calculated using regression analysis and compared with a threshold value at which pathologic bone resorption might develop.Results:The resulting peak stresses showed that bone pieces with thicker cortical bone tolerated higher force magnitudes better than did thinner ones. For cortical bone thicknesses of 0.5, 1.2, 2.0, and 3.0 mm, the maximum force magnitudes that could be applied safely were 3.75, 4.1, 4.3, and 4.45 N, respectively.Conclusions: For the purpose of diminishing orthodontic microimplant failure, an optimal force that can be safely loaded onto a microimplant should not exceed a value of around 3.75–4.5 N.     

Optimal asymmetric thread for orthodontic microimplants: Laboratory and clinical evaluation

Objectives:To investigate the performance of microimplants incorporating a newly designed asymmetric thread.Materials and Methods:Three microimplants were compared. The control group comprised microimplants with the original v-shaped thread. The two experimental groups (Taper 1.0 and Taper 1.25) comprised prototype microimplants constructed with the new asymmetric thread; the Taper 1.25 specimens had a 1.25-mm-long and sharper tip, while the Taper 1.0 and control groups had a less sharp 1-mm tip. Two specially designed artificial bone blocks mimicking soft (maxillary) and hard (mandibular) bone were used to evaluate the microimplant insertion characteristics and postinsertion lateral stability. The peak insertion torque, insertion time, Periotest value (PTV), and torsional strength were measured. Then the microimplants were evaluated clinically over a 3-month period.Results:Significant differences in peak insertion torque, insertion time, and PTV were observed and favored the experimental groups. Although statistically insignificant, the clinical success rate was also higher in the Taper 1.25 experimental group than in the control group (87.2% vs 75.6%).Conclusions:The better performances of the experimental microimplant, under both laboratory and clinical conditions (although statistically insignificant in the latter), demonstrate the superiority of the new asymmetric thread.     

正畸微种植体支抗即刻加载的稳定性研究

目的 本研究通过观察即刻加载的微种植体支抗周围骨界面组织学变化,旨在探索即刻加载是否会影响微种植体支抗的稳定性.方法 本试验选用成年狗1只,16枚正畸用微种植体植入狗的下颌骨后即刻施加1.5 N力,施力9周后狗被处死.骨标本作病理切片后进行组织学观察和测量.结果 微种植体可以承受即刻加载的1.5 N正畸力而无松动.组织学观察显示骨-微种植体界面有骨组织沉积,没有纤维组织生成,即刻加载的正畸力没有影响骨细胞在微种植体表面的沉积.结论 在严格控制植入创伤、加载力量大小的前提下,微种植体的即刻加载是可行的.     

Factors associated with the stability of titanium screws placed in the posterior region for orthodontic anchorage.

Recently, implant anchors such as titanium screws have been used for absolute anchorage during edgewise treatment. However, there have been few human studies reporting on the stability of implant anchors placed in the posterior region. The purpose of this study was to examine the success rates and to find the factors associated with the stability of titanium screws placed into the buccal alveolar bone of the posterior region. Fifty-one patients with malocclusions, 134 titanium screws of 3 types, and 17 miniplates were retrospectively examined in relation to clinical characteristics. The 1-year success rate of screws with 1.0-mm diameter was significantly less than that of other screws with 1.5-mm or 2.3-mm diameter or than that of miniplates. Flap surgery was associated with the patient's discomfort. A high mandibular plane angle and inflammation of peri-implant tissue after implantation were risk factors for mobility of screws. However, we could not detect a significant association between the success rate and the following variables: screw length, kind of placement surgery, immediate loading, location of implantation, age, gender, crowding of teeth, anteroposterior jaw base relationship, controlled periodontitis, and temporomandibular disorder symptoms. We concluded that the diameter of a screw of 1.0 mm or less, inflammation of the peri-implant tissue, and a high mandibular plane angle (ie, thin cortical bone), were associated with the mobility (ie, failure) of the titanium screw placed into the buccal alveolar bone of the posterior region for orthodontic anchorage.     

Radiographic and surgical template for placement of orthodontic microimplants in interradicular areas: a technical note

PURPOSE: In recent years, microimplants have gained popularity in orthodontics. Microimplants are primarily placed in complex sites where critical anatomic structures, such as roots of teeth, may be damaged, so precise surgical planning is required prior to placement. The goal of this report was to introduce a newly developed technique for the placement of microimplants in interradicular areas and evaluate its accuracy. MATERIALS AND METHODS: The planned placement site is radiographed using a radiographic template and film holder fabricated by the investigators. The resultant radiograph is clipped and attached to the radiographic template to make a surgical template to guide the placement of the microimplant. Forty-one patients, 15 men and 26 women ranging in age from 21 to 29 years, were enrolled in this study. On 1 side of the arch, this novel technique was used for implant placement, and on the other side, an established method reported by Maino and associates (i.e., the control technique) was used. RESULTS: A total of 116 microimplants 2 mm wide and 9 mm long were placed interradicularly in 41 patients. Twelve of 58 microimplants were placed unsuccessfully in the control group, versus 2 of 58 in the test group. Statistical analysis showed that there was a significant difference between the 2 techniques in terms of success rate (P < .05). DISCUSSION: Presurgical diagnosis of bone quantity and transfer of the information to the surgical sites are vital in microimplant placement. Radiographic templates modified for surgical purposes have the advantage of transferring radiographic information directly to the surgical site. CONCLUSION: This study, although limited in some respects, demonstrated that microimplant placement can be improved using the newly developed technique described.     

微型正畸支抗种植体即刻挤压植入时骨界面应力分析

目的研究微型正畸支抗种植体即刻植入时骨界面应力大小及分布,为微型支抗种植体即刻加载提供参考。方法将局部下颌骨简化成一个等腰梯形,颌骨骨块长20mm,断面高为30mm,上边宽为10mm,底边宽14mm,皮质骨厚度设定为1.6mm;微型种植体直径设定为1.2mm,长6mm。利用ANSYS9.0软件,建立局部微型种植体-骨的三维有限元模型。下颌骨材料属性设定为线性、正交各向异性,种植体-骨界面定义为完全连接。将断端处、下颌骨局部骨块面及底面的所有节点给予刚性约束。模拟种植体即刻植入时的情况,将骨界面初始位移设定为0、0.05、0.1mm,分析各指定初始位移时骨界面应力大小及分布。结果即刻加载时,0mm初始位移下,种植体骨界面无应力分布;初始位移为0.05mm时,骨界面应力集中在骨皮质内,分布较均匀,衰减幅度很小,近远中方向上的VonMises应力为1648MPa,龈向为1782MPa。初始位移为0.1mm时,近远中方向上的VonMises应力为2012MPa,龈向为2110MPa。结论微型种植体挤压植入时会产生较大的初始应力,即刻加载时,应当考虑这种初始应力。     

Histologic evaluation of early human bone response to different implant surfaces

BACKGROUND: Studies have demonstrated that roughened dental implant surfaces show firmer bone fixation and an increased percentage of bone-to-implant contact (BIC%) compared to commercially pure titanium-surface (machined) implants. Therefore, the purpose of this study was to evaluate the influence of implant-surface topography on human bone tissue after 2 months of unloaded healing. METHODS: Fourteen subjects with a mean age of 46.87 +/- 9.45 years received two microimplants each (2.5 mm in diameter and 6 mm in length), one test (sandblasted acid-etched surface) and one control (machined surface), either in the mandible or in the maxilla. After a healing period of 2 months, the microimplants and surrounding tissues were removed with a trephine bur and prepared for histologic analysis. RESULTS: All microimplants, except for one of the controls, were clinically stable after the healing period. Histometric evaluation indicated that the mean BIC% was 23.08% +/- 11.95% and 42.83% +/- 9.80% for machined and rough microimplant surfaces, respectively (P = 0.0005). The bone area within the threads was also higher for sandblasted-surface implants (P = 0.0005). The mean percentage of bone density did not differ between the two groups (P = 0.578). CONCLUSION: Data from the present histological study suggest that the sandblasted acid-etched implant provides a better human bone tissue response than machined implants under unloaded conditions after a healing period of 2 months.     

The application of mini-implants for orthodontic anchorage

The aim of this study was to explore the use of mini-implants for skeletal anchorage, and to assess their stability and the causes of failure. Forty-five mini-implants were used in orthodontic treatment. The diameter of the implants was 2mm, and their lengths were 8, 10, 12 and 14mm. The drill procedure was directly through the cortical bone without any incision or flap operation. Two weeks later, a force of 100-200g was applied by an elastometric chain or NiTi coil spring. Risk factors for the failure of mini-implants were examined statistically using the Chi-square or Fisher exact test as applicable. The average placement time of a mini-implant was about 10-15min. Four mini-implants loosened after orthodontic force loading. The overall success rate was 91.1%. The location of the implant was the significant factor related to failure. In conclusion, the mini-implants are easy to insert for skeletal anchorage and could be successful in the control of tooth movement.     

Orthodontic Microimplants Assisted Intrusion of Supra-erupted Maxillary Molar Enabling Osseointegrated Implant Supported Mandibular Prosthesis: Case Reports

Loss of mandibular molars, when not replaced in time, are usually associated with overeruption of maxillary molars. To provide prosthetic replacement for missing lower posteriors, over erupted maxillary teeth have been intruded in past with great difficulty in adults with conventional orthodontics, along with associated problems of root resorption. Currently orthodontic microimplants provide stable intraoral anchorage, allow predictable maxillary molar intrusion enabling reestablishment of functional posterior occlusion with mandibular implant supported prosthesis, thereby reducing need for prosthetic crown reduction in maxillary arch. The added advantage of microimplant is it enables use of sectional appliance in area of concern instead of full arch bracketed appliance which an adult may not accept. The case reports demonstrates, overerupted maxillary molars were intruded using orthodontic microimplants to enable prosthetic rehabilitation of mandibular dentition by osseointegrated implant supported prosthesis. The second case report also demonstrates use of CBCT scan in planning and execution.

     

C-orthodontic microimplant for distalization of mandibular dentition in Class III correction

A 16-year-old male patient with a Class III malocclusion and 2 lower missing central incisors presented for treatment. The treatment plan consisted of asymmetrically distalizing the lower dentition and regaining space for lower anterior prosthetic work. C-implants were to be used as anchorage for Class III intermaxillary elastics, and two C-orthodontic microimplants (C-implants) were placed in the interdental spaces between the upper second premolars and first molars. The particular design of the C-implant head minimized gingival irritation during the orthodontic treatment. Sliding jigs were applied on the buccal for distalization of the lower posterior teeth. The correct overbite and overjet were obtained by distalizing the entire lower dentition into its proper position with C-implant anchorage, which contributed to an improvement in facial balance. It took 15 months to treat this case. The application of this new microimplant, considerations for case selection, and the sequence of treatment are presented.     

Do miniscrews remain stationary under orthodontic forces?

Miniscrews have been used in recent years for anchorage in orthodontic treatment. However, it is not clear whether the miniscrews are absolutely stationary or move when force is applied. Sixteen adult patients with miniscrews (diameter = 2 mm, length = 17 mm) as the maxillary anchorage were included in this study. Miniscrews were inserted on the maxillary zygomatic buttress as a direct anchorage for en masse anterior retraction. Nickel-titanium closed-coil springs were placed for the retraction 2 weeks after insertion of the miniscrews. Cephalometric radiographs were taken immediately before force application (T1) and 9 months later (T2). The cephalometric tracings at T1 and T2 were superimposed for the overall best fit on the structures of the maxilla, cranial base, and cranial vault to determine any movement of the miniscrews. The miniscrews were also evaluated clinically for their mobility (0: no movement, 1: < or =0.5 mm, 2: 0.5-1.0 mm, 3: >1.0 mm). The mobility of all miniscrews was 0 at T1 and T2. On average, the miniscrews tipped forward significantly, by 0.4 mm at the screw head. The miniscrews were extruded and tipped forward (-1.0 to 1.5 mm) in 7 of the 16 patients. Miniscrews are a stable anchorage but do not remain absolutely stationary throughout orthodontic loading. They might move according to the orthodontic loading in some patients. To prevent miniscrews hitting any vital organs because of displacement, it is recommended that they be placed in a non-tooth-bearing area that has no foramen, major nerves, or blood vessel pathways, or in a tooth-bearing area allowing 2 mm of safety clearance between the miniscrew and dental root.     

Skeletal and dentoalveolar changes in the transverse dimension using microimplant-assisted rapid palatal expansion (MARPE) appliances

Conventional rapid palatal expansion (RPE) has been proven to be a reliable treatment for correcting transverse maxillary deficiency in young patients. However, side effects including dental tipping and risk of periodontal problem limited its application to young patients after the pubertal growth spurt. Surgically assisted rapid palatal expansion (SARPE), a supplement to RPE, could be applied in skeletally mature patients. However, SARPE was an invasive method, and the morbidity, risks and cost related to surgical treatment might discourage many adult patients. The use of Microimplant-Assisted Rapid Palatal Expansion (MARPE) appliance, which can potentially avoid surgical intervention, is gaining popularity in treatment of maxillary transverse deficiency (MTD) in young adolescent patients. However, the literature on the skeletal and dentoalveolar changes with this appliance is scarce. To evaluate the immediate skeletal and dentoalveolar changes in the transverse dimension with the maxillary skeletal expander (MSE), a MARPE appliance with hybrid anchorage, using cone-beam computed tomography (CBCT). Twenty-two patients (11 males and 11 females, mean age 14.97 ± 6.16 years) with transverse maxillary deficiency were treated using the MSE (Biomaterials Korea, Inc., Seoul, Korea). The appliance consisted of a central expansion screw that were welded to four tubes that served as guides for microimplant placement. The microimplants were 1.8 mm in diameter and 11 mm in length. The longer length of microimplants permitted bicortical engagement of the palatal and nasal floor, reducing the force transmitted to the anchored teeth during expansion. The appliance activation varied with age and skeletal maturity of the patient. The expansion was terminated when 2–3 mm of overexpansion was achieved. CBCT scans were taken before treatment (T1) and immediately after expansion (T2). Measurements were taken to evaluate the amount of total expansion, skeletal expansion, and angular dental tipping at the first molar region. A total expansion of 5.41 ± 2.18 mm was achieved, 59.23 ± 17.75% of which was attributed to skeletal expansion (3.15 ± 1.64 mm) with the first molars exhibiting buccal tipping of 2.56 ± 2.64°. The use of MARPE appliances such as MSE can be used to correct transverse maxillary deficiency in adolescent patients with minimal dentoalveolar side effects.     

Microimplant-based mandibular advancement therapy for the treatment of snoring and obstructive sleep apnea: a prospective study

Objective:To investigate the efficacy of orthodontic microimplant–based mandibular advancement therapies for the treatment of snoring and obstructive sleep apnea (OSA) in adult patients.Materials and Methods:Ten adult OSA patients (seven men, three women; mean age 60.00 ± 9.25 years) were each treated with two mandibular orthodontic microimplants attached to a customized reverse face mask for mandibular advancement. Pretreatment and posttreatment outcome measures of microimplant mobility, apnea-hypopnea index, snoring, respiratory movement, and Epworth sleepiness scores were evaluated after 6 months.Results:Highly significant reductions in the apnea-hypopnea index, snoring, and sleep variables were observed. Sixteen of the 20 (80%) microimplants were stable and showed no mobility, and four (20%) demonstrated grade 1 or 2 mobility and required removal and reinsertion of a new microimplant.Conclusions:Favorable reductions in sleep variables highlight the potential of microimplant-based mandibular advancement therapy as an alternative treatment modality for OSA patients who cannot tolerate continuous positive airway pressure and oral appliance therapy.     

腭部种植体支抗稳定性的临床研究

目的评价腭部种植体支抗系统在临床固定矫治技术正畸治疗中的稳定性。方法将直径5.0mm、长6mm的种植体植入19例错畸形患者上颌前磨牙区腭中缝的硬腭,愈合期4周,以横腭杆连接上颌双侧磨牙和种植体作为强支抗,配合MBT矫治技术常规减数正畸治疗。对种植体植入时和支抗作用完成种植体取出前的头影测量指标进行配对比较。结果本组腭部种植体支抗成功率为84.3%,16颗种植体在口内行使功能的时间10～36个月,平均为(23.08±8.06)个月。种植体植入到种植体取出,IL-X轴分别为(62.88±5.85)mm和(62.45±6.70)mm,IL-Y轴为(36.66±5.41)mm和(37.96±4.90)mm,IAP-PP为(73.81±8.84)°和(74.72±9.22)°,IAP-Y轴为(62.09±9.33)°和(63.85±10.96)°,U6-Y轴为(20.80±5.87)mm和(21.49±6.00)mm,经配对t检验,差异均无统计学意义。结论腭部种植体支抗种植系统承载临床正畸力能保持稳定,从而起到增强磨牙支抗作用。     

Clinical Suitability of Titanium Microscrews for Orthodontic Anchorage—Preliminary Experiences

Abstract. Aim: The future of orthodontic anchorage implants may well belong to micro-implants, developed in varying designs, lengths and diameters by different manufacturers. The aim of the present clinical study was to investigate whether titanium microscrews manufactured by Jeil Medical Corp. (South Korea) are suitable for orthodontic anchorage purposes. Material and Methods: At the Department of Orthodontics, University of Aachen, 36 micro-implants with diameters of 1.4, 1.6 and 2 mm and lengths of 6, 8 and 10 mm were inserted in 17 patients. The implants served predominantly as anchorage for premolar distalization, molar uprighting and molar mesialization. Results: The mean age of the patients was 29 ± 14 years. The implantation sites were evenly divided between the upper and lower jaw. The main insertion sites were buccal interradicular, retromolar, and palatal interradicular. Most implants used were 8 mm in length and 1.6 or 2 mm in diameter. The mean in situ time was 158 ± 97 days. Eleven fixtures failed before the end of treatment, corresponding to a failure rate of 30%. Conclusions: The tested miniscrews with a diameter of 1.6–2 mm and a length of 8–10 mm proved suitable for orthodontic anchorage purposes. Whereas larger implants need a relatively extensive bone supply and the insertion sites are limited, microscrews offer a more flexible range of applications. They also offer crucial advantages such as simple, atraumatic insertion and removal, minimum patient stress, and a favorable cost-benefit ratio.     

磨牙后区微种植体支抗竖直下颌近中阻生第二磨牙的临床应用

目的探讨磨牙后区微种植体应用于下颌近中阻生第二磨牙竖直的正畸治疗方法,评估其效果。方法选择南京医科大学附属口腔医院正畸科2011—2014年门诊下颌第二磨牙近中阻生的患者13例23颗患牙,采用磨牙后区植入微种植体,牵引23颗患牙向远中移动,引导其竖直、萌出。结果 23颗阻生的下颌第二磨牙全部竖直萌出并建立良好的咬合。竖直治疗平均时间为6.5个月。结论磨牙后区微种植体支抗能简单有效地竖直下颌阻生的第二磨牙,并且可以控制磨牙的垂直向高度,避免对相邻牙齿产生不良影响。     

牙周膜牵张成骨快速移动牙齿的组织学观察

目的 观察牙周膜牵张成骨快速移动牙齿的牙周组织学变化。方法 将6只杂种犬随机分为2w，4w，6w三组（每组二只）。拔除两侧第二前磨牙，并随机选择其中一侧为实验侧，另一侧为常规橡皮圈加力方法对照侧。动物基牙预备：拔牙凿骨减阻；粘结自制牵张装置；实验组以2次／天的频率、0．15fnm／次的速率加力，2w后固定保持。对照组以传统橡皮链对移动牙施加100g力值，加力2w后，固定保持。测量支抗牙、移动牙移动距离：分别于第2、4、6w各宰杀二只动物，观察实验侧与对照侧的组织学变化。结果 ①实验侧移动牙加力2w平均向远中移动3．78mm，对照侧移动牙平均向远中移动1．09mm（P〈0．01），实验侧支抗牙平均向近中移动0．42mm，对照侧支抗牙平均向近中移动0．40mm（P〉0．01）。②组织学观察得出：2w组，实验侧与对照侧相比，实验侧牙周膜显著增宽，牙周膜内成纤维细胞增殖，新生板层状牙槽骨明显增多，与牵张作用力方向一致；4w组，旧间隔骨已改建完成，牙周膜宽度基本恢复正常；6如组两种方法作用下移动牙牙周组织己无明显差异。结论 牙周膜牵张成骨可以快速移动牙齿；牙周组织不会出现不可复性损害。