The use of small titanium screws for orthodontic anchorage

The use of conventional dental implants for orthodontic anchorage is limited by their large size. The purpose of this study was to quantify the histomorphometric properties of the bone-implant interface to analyze the use of small titanium screws as an orthodontic anchorage and to establish an adequate healing period. Overall, successful rigid osseous fixation was achieved by 97% of the 96 implants placed in 8 dogs and 100% of the elastomeric chain-loaded implants. All of the loaded implants remained integrated. Mandibular implants had significantly higher bone-implant contact than maxillary implants. Within each arch, the significant histomorphometric indices noted for the "three-week unloaded" healing group were: increased labeling incidence, higher woven-to-lamellar-bone ratio, and increased osseous contact. Analysis of these data indicates that small titanium screws were able to function as rigid osseous anchorage against orthodontic load for 3 months with a minimal (under 3 weeks) healing period.     

The Anchorage Quality of Mini-implants towards Translatory and Extrusive Forces

AIM: The objective of the present experimental animal study was to investigate the stability of mini-implants (submersion depth 4 mm, ? 3.3 mm) for orthodontic anchorage. Additionally the histomorphologic effects of orthodontic loading were to be analyzed, especially with regard to the activity and location of periimplant osteodynamic reactions. MATERIAL AND METHOD: 16 titanium implants (Orthosystem, Straumann, Waldenburg, Switzerland) were inserted in edentulous areas of the upper and lower jaw of four foxhounds. After a 6-month healing period the fixtures were loaded with extrusive forces (50 cN) in group 1, and with translatory forces (200 cN) in group 2. The osteodynamic changes during the 6-month force application period were documented using stains with calcium affinity (polychrome sequential labeling). The histologic analysis comprised: microsection method, fluorescence microscopy, toluidine blue staining, histomorphometry. RESULTS: All osseointegrated implants were stable throughout the test period. With respect to the apposition lines, the histomorphometric analysis showed more distinct osteodynamic activity in extrusively loaded than in translatorily loaded implants. The activity was more pronounced in the marginal area than in intermediate and apical implant areas. The extent of peri-implant remodeling activity was up to 980 micro m after extrusive loading and 300-700 microm after translatory loading. CONCLUSIONS: The results suggest that even mini-implants are suited to orthodontic anchorage tasks. The question of the required minimum size of orthodontic anchorage implants remains unanswered.     

Effects of a cell adhesion molecule coating on the blasted surface of titanium implants on bone healing in the rabbit femur

PURPOSE: One strategy to improve implant osseointegration is to control the quality of the bone reaction at the implant-bone tissue interface using an implant coated with biologically active substances. The purpose of this study was to investigate the effect of a tetra-cell adhesion molecule (T-CAM) coating composed of 4 cell-adhesion molecules-an arginine-glycine-aspartic acid (RGD) sequence, a proline-histidine-serine-arginine-asparagine (PHSRN) sequence, a tyrosine-histidine sequence (YH), and a glutamic acid-proline-aspartic acid-isoleucine-methionine (EPDIM)-on the rough-surfaced titanium implant on peri-implant bone formation in the rabbit femur with poor local bone conditions and minimal primary stability. MATERIALS AND METHODS: Seven T-CAM-coated (blasted/T-CAM) and uncoated (blasted) implants with a rough surface (hydroxyapatite-blasted; Ra = 1.8 microm) were placed in slightly oversized beds of the metaphyses of the right and left femurs of 7 New Zealand White rabbits with light tactile pressure, and minimal primary stability was obtained. To evaluate the effects of T-CAM coating on the peri-implant bone healing response, histomorphometric analysis was performed 8 weeks after surgery. The 2 groups were compared using the Student t test, with a significance level of P < .05. RESULTS: Compared to uncoated blasted implants at 8 weeks of healing, the blasted/T-CAM implants showed a significantly greater amount of bone-implant contact (BIC; P < .01) and new bone formation in the zones 0 to 100 microm and 0 to 500 microm lateral to the implant surface (P < .05) in the medullary space. CONCLUSION: The T-CAM coating on the rough-surfaced titanium implants significantly enhanced peri-implant bone formation in rabbit femurs with poor local bone condition.     

Early bone response to sandblasted,dual acid-etched and H2O2/HCl treated titanium implants: an experimental study in the rabbit

The aim of this study was to evaluate the influence of a roughened H₂O₂/HCl heat-treated titanium surface on peri-implant bone formation at an early stage in vivo. 24 Ti₆Al₄V alloy implants were used; half were treated by sandblasted and dual acid-etched treatments (control group), while the others were treated by sandblasted, dual acid-etched and H₂O₂/HCl heat treatments (test group). The morphology and roughness were analyzed by field emission SEM and atomic force microscopy. The implants were inserted into the femora of 12 adult white rabbits. After 2 and 4 weeks, femora block specimens were prepared for histological and histomorphometric analysis. SEM micrographs showed that multilevel and different sized pits were formed on both surfaces. New bone formation was observed on both implant surfaces. Test implants demonstrated a greater mean percentage of bone-implant contact as compared with controls at 2 (46.84 vs. 41.81, p=0.000) and 4 weeks (49.43 vs. 44.87, p=0.006) of healing. It is concluded that the H₂O₂/HCl heat-treated rough titanium surface promoted enhanced bone apposition during the early stages of new bone formation around the implant.     

正畸治疗中磨牙的拔除和保留(三十七)——牙槽外区域种植支抗的应用及临床意义

目的：介绍并总结微螺钉在牙槽外区域植入的应用方法。方法：选择80例需种植支抗配合矫治的病例,其中35例在牙槽间隔位置常规植入128个微螺钉,45例在牙槽外区域植入166个微螺钉。对两组微螺钉的松脱情况及黏膜包埋情况进行统计分析。结果：牙槽间隔组微螺钉的松脱率和黏膜包埋率分别是17.19%和17.97%,而牙槽外种植组分别是9.64%和2.41%。结论：微螺钉在牙槽外区域的应用有显著的优点,可以替代常规微螺钉及微钛板临床种植的应用,尤其适合拔除磨牙矫治的病例。     

Bone-implant contact on machined and dual acid-etched surfaces after 2 months of healing in the human maxilla

BACKGROUND: Recent clinical studies indicate that an implant with a textured surface may be loaded sooner than traditional healing protocols have recommended. In a previous study, the 6-month bone-implant contact for dual acid-etched and machined implant surfaces was reported to be 72.96% and 33.98%, respectively. In 1991, a minimum of 50% bone-implant contact was considered necessary for loading to ensure long-term survival of the implant. This study evaluated the 2-month bone-implant contact for dual acid-etched and machined implant surfaces to determine if this criterion had been met. METHODS: Custom manufactured implants (2 mm diameter and 5 mm length), having on one side a machined surface and on the other side a dual acid-etched surface, were placed in the posterior maxilla of 11 patients, allowed to integrate for 2 months, then removed using a 4 mm internal diameter trephine with irrigation. Sections were processed and stained for histologic and histomorphometric analysis. The parameters calculated for each section were: bone volume (BV%), actual percent bone-implant contact (BIC%), and expected bone contact (EBC%) as determined from 3 implant images superimposed onto the adjacent bone 150, 500, and 1,000 microm lateral to the actual implant surface and representing the bone-implant contact expected on the day the implant was placed, based on the peri-implant bone volume. RESULTS: Histomorphometric analysis indicated that the mean BV% of 36.77% from all sections was closely matched to the mean EBC% of 34.36% (P<0.001). The analysis showed that after 2 months of healing, the 47.81% BIC% on the dual acid-etched side was statistically higher (analysis of variance, P<0.001) than the 19.00% BIC% on the machined side. In areas of low-density bone (<40% BV%), the difference between the BIC% for the machined and dual acid-etched sides was even greater. Nine of the 11 dual acid-etched sides had a higher BIC% than the EBC% value. In the machined group, 1 of the 11 sides had a higher BIC% value than the EBC% value. The bone surrounding the dual acid-etched surface was a woven bone with thin, connecting peri-implant bony trabeculae projecting into and between the threads. Bone on the machined side was observed mostly contacting the tips of the screw threads. CONCLUSIONS: At 2 months, the mean BIC% for the dual acid-etched group increased 39.14% compared to the EBC% value, while the mean BIC% for the machined group decreased 44.70%. Based on the histomorphometric results of this study, sufficient bone for functional loading of the implant exists on a dual acid-etched surface after 2 months of healing in the posterior maxillary arch.     

Long-term follow-up of dental single implants under immediate orthodontic load

Objective:To evaluate the success of osseointegrated implants under immediate prosthetic and orthodontic forces after a follow-up period of at least 2 years.Materials and Methods:The sample included 20 titanium implants which were used as orthodontic and prosthetic anchorage of immediately loaded single-crowns on a total of 13 patients. A 40 N initial torque was considered the minimum for inclusion in the sample. All implants received screwed provisional crowns immediately after surgery. The implants were randomly divided into two groups: the control group (9 implants) and the immediate orthodontic loading group (11 implants). A healing period of 4 months was observed before orthodontic loads were applied to the control group implants. For the immediate orthodontic loading group, orthodontic forces were applied within 24 hours. The maximum orthodontic force applied in both groups was 200 g. After 6 months of orthodontic movement, clinical and radiographic evaluations were obtained. Implants were considered successful when favorable results were obtained in all evaluations.Results:After a 2-year follow-up, the success rates were 90.9% and 88.9%, respectively, in the orthodontic loading group and the control group. Each group had one failure.Conclusion:Shortening the healing period for the application of orthodontic forces did not seem to affect the success of osseointegrated implants used as anchorage.     

Immediate Loading of Palatal Implants in Stillgrowing Patients: a Prospective, Comparative, Clinical Pilot Study

OBJECTIVE: The objective of this prospective, comparative study was to evaluate the potential of allowing immediate (within 72 hours) loading of palatal implants used for maximum orthodontic anchorage. This is in contrast to the standard protocol calling for a healing period of 12 weeks. MATERIALS AND METHODS: Sixteen patients with a mean age of 14.22+/-1.37 years for whom orthodontic treatment with maximum anchorage was indicated were randomized into two groups. In the SB (immediate loading) group (n=8, mean age 14.15+/-1.2 years), the implants were employed to provide maximum anchorage for a 1.2 x 1.2 mm TPA wire in combination with a molar band within 72 hours of insertion. In the KB (conventional loading) group (n=8, mean age 14.30+/-1.57 years), the implants were not used for maximum anchorage until a 12-week healing period had elapsed. Patients in both groups with implants that were clinically unstable after insertion were excluded from the study. After conclusion of the treatment, the implants were explanted and embedded using the sawing-grinding technique after Donath. Bone-implant contact (KIK) was analyzed using Bioquant Osteo software version 7.10.10. RESULTS: The objective of the orthodontic treatment, to achieve maximum anchorage of the first molars, was achieved in both groups. In the SB group, the mean bone-implant contact was 55.0%+/-21.6. In the KB group, the mean bone-implant contact was 73.1%+/-19.8. With a p-value of 0.1661, the difference between the bone-implant contact values was not statistically significant. CONCLUSION: The results of our clinical study demonstrate that when implants are clinically stable following insertion, it seems that a 12-week healing phase during which the implants are not loaded leads to a non-statistically significant improvement in osseointegration.     

正畸治疗中磨牙的拔除和保留（四十五）——牙槽外正畸支抗钉种植的部位及应用

目的：分析微螺钉作为骨性之抗在牙槽外区域种植的部位及其临床应用。方法：总结近3年内100例应用骨性支抗辅助治疗的正畸病例的支抗钉应用情况。结果：作为骨性支抗,微螺钉植入部位主要在上颌颧牙槽嵴和下颌颊棚区。结论：骨性支抗实现了真正意义上的绝对支抗。     

腺相关病毒介导的骨形态发生蛋白7基因促种植体周骨缺损修复的实验研究

目的观察载bmp7基因的腺相关病毒（rAAV- BMP7）复合Bio- Oss的基因治疗方法对种植体周骨缺损修复的影响。方法体外构建载bmp7基因的腺相关病毒,并与Bio- Oss复合。6只雄性新西兰大白兔双侧胫骨植入种植体,并制备直径8 mm、深4 mm的种植体周骨缺损,A组骨缺损区填入rAAV- BMP7/Bio- Oss复合物;B组仅填入Bio-Oss;C组不充填材料。术后4、8周分期处死动物,取样进行组织学观察和形态学分析。结果A、B组骨缺损处均有新骨形成,A组较B组新骨形成更早、新生骨量更多、骨成熟程度更高（P<0.05）。结论rAAV- BMP7复合Bio- Oss较单纯植入Bio- Oss能更快、更有效地促进种植体周围骨缺损形成新骨,新骨量大且成熟度高,并能形成理想的种植体- 骨结合界面。     

Short epithetic implants for orthodontic anchorage in the paramedian region of the palate

Orthodontic movement of teeth often requires maximum anchorage, so that additional resistance must be added to teeth to avoid reaction to reciprocal forces. Thus, use of endosseous implants may be a valuable alternative for ensuring stable intraoral anchorage. This study was designed to evaluate the efficacy of short epithetic implants for orthodontic anchorage in the paramedian region of the palate. Twenty-one patients (15 female, 6 male; mean age 25.8+/-9.9 yrs, min 12.7, max. 48.1) were included in this study. Following adequate preoperative planning, an implant system with reduced length, which had already been used for anchorage of epitheses, was placed in the paramedian region avoiding the anterior palatine suture. After a mean period of 4 months with unloaded healing, the implants were subjected to direct or indirect orthodontic loading. Despite varying bone quality and varying vertical bone volume in this region, adequate primary stability was achieved for all of the implants. No implant was lost during the healing period. Three out of the 21 implants placed were considered as failures. Two implants loosened shortly after the start of orthodontic loading. One of these was lost at a later stage due to peri-implant inflammation, while the other one was left in place during the 9-month follow-up period because no inflammation developed and this implant is still indirectly included in the orthodontic treatment. Another implant loosening was observed after 8.5 months following direct loading with 8 N. This implant was also lost due to peri-implant inflammation. The time-related survival probability was 84.8% after 22.9 months. As yet, 4 implants have been removed due to completion of orthodontic treatment. The results of this study indicate that short epithetic implants are suitable to achieve maximum anchorage in the paramedian region of the hard palate in orthodontic treatment.     

A study on orthodontic bone-bonding anchorage

Objectives:The study had two objectives: (1) to measure the maximum loading capacity of a new skeletal orthodontic anchorage, designated the “bone-bonding anchorage,” and (2) to study its histological basis.Materials and Methods:A total of 81 bone-bonding anchorages were fixed onto the surface of the tibia of 12 big-ear white rabbits with N-2-butyl cyanoacrylate. The 12 animals were divided into groups designated as the immediate, 2-week, 4-week, and 8-week after-surgery groups. The maximum loading capacity of each group was measured, and histological changes were observed.Results:The results indicate a tendency toward an initial decrease and then an increase in the maximum loading capacity of the bone-bonding anchorage. The mean value of the 8-week group reached 45.69 N, which can satisfy orthodontic clinical needs. Histologically, new bone formation was found around the base of the bone-bonding anchorage, which wrapped the base until it was bone-buried, creating the histological basis of the maximum loading capacity. In the experiment, the total failure rate of the bone-bonding anchorage was 13.6%, and no failure occurred in the immediate and 8-week groups.Conclusion:The loading capacity of the bone-bonding anchorage is sufficient for orthodontic use, but whether or not it can be applied to clinical practice merits further study.     

An easy way to apply orthodontic extraction for impacted lower third molar compressing to the inferior alveolar nerve

PurposeTo study the results of an easy orthodontic extraction method for impacted lower third molar removal which had roots compressing to the inferior alveolar nerve (IAN).Patients and methodsForty patients were divided into two groups according to their desire. Orthodontic traction group (n = 20) had brackets or mini bone screws on the antagonist maxillary molars as anchorage for orthodontic traction from 3 to 10 weeks until the roots’ tip was away from the IAN, the tooth was then removed. Traditional extraction group (n = 20) had the tooth removed immediately by the same surgeon. Post-operative results were compared between the two groups.ResultsAll 20 patients in the orthodontic extraction group had their lower impacted third molar removed easily without lower lip numbness after surgery, while 5 patients in the traditional extraction group had transient IAN injury and went away 1 week later. There were no anchorage teeth and adjacent mandibular second molar loose or displacement.ConclusionApplication of orthodontic brackets or mini bone screws on the antagonist maxillary molars is an easy way for orthodontic extraction of impacted lower third molar with roots’ tip compressed to the IAN. It is an effective way to avoid IAN injury during tooth extraction.     

Resonance frequency measurements of implant stability in the dog mandible: experimental comparison with histomorphometric data

The aim of the present study was to test the hypothesis that measurements of implant stability using resonance frequency analysis (RFA) correlate with histomorphometric data of bone anchorage. Ten adult female foxhounds received a total of 80 implants in their mandibles 3 months after removal of all premolar teeth. At the time of implant placement, torque required for bone tapping was registered as a measure of bone density and immediately after placement implant stability was assessed using RFA. RFA measurements were repeated at the time of implant retrieval after 1 month (5 dogs) and 3 months (5 dogs). Peri-implant bone regeneration was assessed histomorphometrically by measuring bone-implant contact (BIC) and the volume density of the newly formed peri-implant bone (BVD). RFA values at the time of implant placement did not correlate with the torque required to tap the bone for implant placement. After 1 and 3 months, RFA values were significantly increased compared with baseline values. BIC and BVD, however, had increased significantly during this interval. There was no correlation between bone-implant contact and RFA values nor between peri-implant bone density and RFA values. Thus, the hypothesis could not be verified. It is concluded that the validity of the individual measurement of implant stability using RFA should be considered with caution.     

低幅高频振动对比格犬种植体周围骨愈合和种植体骨结合的影响

目的:低幅高频(low-magnitude high-frequency,LMHF)振动已被证实在骨愈合中起到重要作用.本研究旨在评估LMHF振动直接加载于纯钛种植体后,对种植体周骨愈合及种植体骨结合的影响.方法 :6 只拔除下颌前磨牙及磨牙的雄性比格犬常规饲养3 个月后,在双侧下颌骨前磨牙及磨牙区分别植入3 颗纯钛种...     

Threaded versus porous-surfaced implants as anchorage units for orthodontic treatment: three-dimensional finite element analysis of peri-implant bone tissue stresses

PURPOSE: A 3-dimensional finite element model was developed to investigate the cause of different crestal bone loss patterns observed around sintered porous-surfaced and machined (turned) threaded dental implants used for orthodontic anchorage in a previously reported animal study. MATERIALS AND METHODS: Twenty-noded structural solid elements with parabolic interpolation between nodes were used for modeling the bone-implant interface zone. A 3-N traction force acting between either 2 porous-surfaced or 2 machined threaded implants placed in canine premolar mandibular sites and bone profiles observed at initiation and 22 weeks of orthodontic loading were modeled. RESULTS: Higher maximum stresses in peri-implant bone next to the coronal region of the implants were predicted with the machined threaded implants at both the initial and final time points, with the values 20% greater than those predicted after the 22-week loading period. These values were approximately 200% greater than those predicted for the porous-surfaced implants, for which a more uniform stress distribution was predicted. DISCUSSION: The finite element model results indicated that the observed greater retention of crestal bone next to the porous-surfaced implants was attributable to lower peak stresses developing in crestal peri-implant bone with this design, which decreased the probability of bone loss related to local overstressing and bone microfracture. CONCLUSION: The predicted lower stresses were a result of the more uniform transfer of force from implant to bone with the porous-surfaced implants, which was a consequence of the interlocking of bone and implant possible with this design.     

正畸治疗中磨牙的拔除和保留（四十七）——骨钉在矫治正畸失败和复发病例中的运用

目的：分析骨钉在正畸失败或复发病例进行二次矫治中的应用。方法：总结近4年来20例正畸矫治失败或复发病例的再矫治情况。结果：除9例轻度复发者通过活动或固定矫治器进行简单矫治外,其余11例均通过减数一组磨牙和骨钉的应用得以矫治。结论：通过减数一组磨牙和骨钉的应用,使再矫治病例取得满意效果。     

Direct versus indirect loading of orthodontic miniscrew implants—an FEM analysis

Objective

The mesialization of molars in the lower jaw represents a particularly demanding scenario for the quality of orthodontic anchorage. The use of miniscrew implants has proven particularly effective; whereby, these orthodontic implants are either directly loaded (direct anchorage) or employed indirectly to stabilize a dental anchorage block (indirect anchorage). The objective of this study was to analyze the biomechanical differences between direct and indirect anchorage and their effects on the primary stability of the miniscrew implants.

Materials and methods

For this purpose, several computer-aided design/computer-aided manufacturing (CAD-CAM)-models were prepared from the CT data of a 21-year-old patient, and these were combined with virtually constructed models of brackets, arches, and miniscrew implants. Based on this, four finite element method (FEM) models were generated by three-dimensional meshing. Material properties, boundary conditions, and the quality of applied forces (direction and magnitude) were defined. After solving the FEM equations, strain values were recorded at predefined measuring points. The calculations made using the FEM models with direct and indirect anchorage were statistically evaluated.

Results

The loading of the compact bone in the proximity of the miniscrew was clearly greater with direct than it was with indirect anchorage. The more anchor teeth were integrated into the anchoring block with indirect anchorage, the smaller was the peri-implant loading of the bone.

Conclusions

Indirect miniscrew anchorage is a reliable possibility to reduce the peri-implant loading of the bone and to reduce the risk of losing the miniscrew. The more teeth are integrated into the anchoring block, the higher is this protective effect.

Clinical relevance

In clinical situations requiring major orthodontic forces, it is better to choose an indirect anchorage in order to minimize the risk of losing the miniscrew.     

Tapered orthodontic miniscrews induce bone-screw cohesion following immediate loading

The aim of this study was to investigate the initial stability of tapered orthodontic miniscrews (T-type screws) after placement, the necessity of a healing period, and the propriety of immediate loading. Twenty male Wistar rats with a mean age of 20 weeks were divided into two groups. In the immediate-loading groups, straight orthodontic miniscrews (S-type screws) and T-type screws (five rats each) underwent experimental traction force for 2 weeks (W) immediately after placement. In the healing groups (S- and T-type, five rats each), force was applied for 2 W after a 6-W healing period. The right tibia in each rat was identified as the test limb, while the left tibia in each rat was used as the control group, and underwent no experimental force during the experimental period. The screw-to-bone contact was observed histologically and the bone-screw contact ratio was calculated. Scheffe's test was performed to compare the bone-screw contact ratio in each group using statistical software package (SPSS 8.0 for Windows). In the control group, the bone-screw contact ratio improved from 34.8 +/- 16.0 to 74.8 +/- 12.0 per cent with S-type screws in proportion to the experimental period (2 to 8 W, respectively). With the T-type screws in the test group, there was no significant difference between the immediate-loading and healing groups. In the immediate-loading group, the bone-screw contact ratio with T-type screws was significantly greater (82.3 +/- 15.0 per cent) than with the S-type screws (33.3 +/- 11.8 per cent; P < 0.05), suggesting that T-type screws can be used for orthodontic anchorage immediately after placement.     

Osseointegration of miniscrews: a histomorphometric evaluation

Mini-implants and miniscrews are commonly used in orthodontics to provide additional temporary intraoral anchorage. Partial osseointegration represents a distinct advantage in orthodontic applications, allowing effective anchorage to be combined with easy insertion and removal. This article reports the histomorphometric findings of the osseointegration of bracket screw bone anchors (BSBAs). In an experimental animal study, four BSBAs were inserted in the alveolar process of the lower jaw in each of five male beagle dogs, aged 6.5 months from the same mother. Eleven screws were lost during the study, nine of them due to lack of primary stability. One screw was removed at the end of the examination period for evaluation of ease of removal. After 6 months, histological evaluation of the eight remaining screws was performed to evaluate the extent of osseointegration. All eight screws showed partial osseointegration (mean 74.48 per cent, standard deviation +/- 15.33 per cent). The amount of osseointegration was independent of loading time and location (anterior or posterior), as tested with an independent samples t-test (P > 0.05). Analysis of the data indicated that small titanium screws were able to function as rigid osseous anchors against an orthodontic load of 200 cN for 6, 12, 18, or 24 weeks after a minimal healing period or no healing period. These findings show that miniscrews, used for temporary anchorage in orthodontics, partially osseointegrate.