Primary loading of palatal implants for orthodontic anchorage--a pilot animal study.

OBJECTIVES: This study aimed at evaluating the clinical performance and osseointegration of short orthodontic implants immediately loaded with orthodontic forces. MATERIAL AND METHODS: The investigation was designed as an experimental animal study. Eight palatal implants of the Ortho-system were immediately loaded with 100 cN after palatal insertion in 4 female German shepherd dogs. Xylene orange and calcein green were used for polychrome sequential labelling. Histological preparation utilized the cutting and grinding technique. Outcome variables were clinical implant success, histological osseointegration and bone-to-implant contact rates. RESULTS: All (8/8) implants were clinically successful and stable when the animals were sacrificed. One implant showed fibrous encapsulation and was histologically classified as "failed" for "osseointegration". Upon morphometrical analysis, bone to implant contact rates for newly formed or remodelled bone were 19% at 4 weeks and 26% at 6 months. The fluorochrome labelling indicated substantial mineral apposition on the surface of the implants at the end of the first and the second postoperative months. CONCLUSION: This study revealed borderline reliability of osseointegration for immediately loaded palatal implants but reasonable bone formation at the 4th postoperative week. Thus, two clinical concepts are both supported: early orthodontic loading after 4 weeks as well as improvement of primary stability to provide a biomechanical basis for immediate orthodontic loading.     

支抗种植体的组织学研究进展

支抗种植体是近年来国内外正畸学研究的热点之一。作者通过组织学研究的文献回顾,反映出支抗种植体微螺钉化、自攻化的发展方向。虽然种植支抗的加力时机尚有争论,但微螺钉存在骨结合,可即刻加力、长期应用,牙周损伤可自愈等新观点对传统认识提出了挑战。     

Rigid endosseous implant utilized as anchorage to protract molars and close an atrophic extraction site

A two-stage endosseous implant, placed in the retromolar area of the mandible was utilized as rigid anchorage to translate two molars 10-12 millimeters mesially into an atrophic endentulous ridge. Despite substantial anchorage demand over a three year period, the endosseous implant remained rigid ("osseointegrated"). At the end of treatment the implant and adjacent, intravitally labeled bone were recovered. Microradiographic and polarized light analyses revealed that about 80 percent of the endosseous portion of the implant was in direct contact with mature lamellar bone. Bone labels demonstrated a remarkably high remodeling rate (about 30 percent/year) for cortical bone within 0.5 millimeter of the interface. Continuous remodeling may be the long-term mechanism whereby loaded implants resist bone fatigue and maintain "osseointegration." Clinical use of orthodontic implants, placed outside the dental arches, requires careful attention to soft tissue management.     

Anchorage effect of osseointegrated vs nonosseointegrated palatal implants

Palatal implants can be used with a transpalatal arch (TPA) connected with the second premolar to provide anchorage. The purpose of this study was to compare the anchorage effects of an osseointegrated palatal implant (OPI) with a nonosseointegrated palatal implant (NOPI), using finite element analysis. One model, which was composed of two maxillary premolars, periodontal ligament (PDL), alveolar bone, a palatal implant, palatal bone, a bracket, band, and TPA, was created on the basis of the clinical situation. The palatal implant was treated as either NOPI or OPI. The force on the premolars was investigated under three conditions: a distomesial horizontal force, a buccolingual horizontal force, and a vertical intrusive force. The PDL stress was calculated and compared with a model without an implant. The result showed that OPI could reduce PDL stress significantly. (The average stress was reduced by 14.44% for the distomesial horizontal force, 60.28% for the buccolingual horizontal force, and 17.31% for the vertical intrusive force.) The NOPI showed almost the same anchorage effect as OPI. The stress on the NOPI surface was higher than that on the OPI surface, but the stress was not high enough to result in failure of the implant. These results suggested that waiting for osseointegration might be unnecessary for an orthodontic implant.     

Biological reactions of alveolar bone to orthodontic loading of oral implants

Enosseous oral implants have been suggested as anchorage for orthodontic appliances in cases where the existing dentition cannot provide sufficient stability. Long-term studies of oral implants have suggested that excessive loading may contribute as an etiologic factor in the pathogenesis of failing implants. The purpose of the present study was to perform a histomorphometric analysis of tissue reactions around implants subjected to a well-defined force system. The analysis was performed on undecalcified sections cut perpendicularly to the long axis of the implant. The degree of osseointegration, bone density at varying distances from the implant as well as the relative extent of resorption and formation of alveolar bone adjacent to the implant-bone interface were evaluated. The results were correlated with the local strain of the tissue estimated by the means of a finite element analysis. It was found that loading significantly influenced both the turnover and the density of the alveolar bone in the proximity of the implants. However, even unloaded implants tended to maintain the bone characteristics of the alveolar process. On the other hand, the degree of osseointegration appeared to be independent of the loading of the implant.     

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.     

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提要：钛和钛合金因具有良好的机械力学性能和生物相容性被广泛用作牙科种植体。种植体植入机体后,与骨的骨性结合是关系到种植体在体内维持时间长短的关键。种植体进入机体后,首先是其表面与组织接触,因此对种植体表面改性是提高种植体与骨的骨性结合的有效方法。本文对目前钛和钛合金表面改性的方法进行简要概述。     

正畸支抗种植体骨整合与稳定性的实验研究

目的　考察正畸支抗种植体的骨整合与稳定性以及二者之间的关系。方法　将HA涂层钛种植体、钛浆喷涂钛种植体、未涂层钛种植体植入狗股骨 ,愈合期后施加 1 96N正畸力 2个月。测量施力后种植体的位置变化和种植体—骨界面的剪切结合强度 ,用扫描电镜观察界面。结果　 3种种植体位移分别为 (- 0 5 0± 1 78)mm、(- 0 0 5± 1 76 )mm、(0 2 9± 1 77)mm ,统计学分析结果显示 ,还不能认为 3种种植体出现移动。 3种种植体—骨界面的剪切结合强度分别是 (2 88± 0 5 5 )MPa、(1 89± 0 81)MPa和 (2 14± 0 49)MPa。HA涂层种植体与骨紧密结合 ,其界面结合强度最高 ;另外 2种种植体与骨的结合强度差异无显著性。结论　虽然HA涂层种植体与骨结合最牢固 ,但 3种种植体—骨界面均可形成骨整合 ,在常规正畸力作用下不会发生明显移动。本项研究结果表明 ,种植体可用作短期的正畸支抗。     

Implant osseointegration in the absence of primary bone anchorage: a clinical report

The authors identified no report describing implant primary stability obtained by external fixation as a means to achieve osseointegration in craniofacial settings. This article describes a situation in which an implant was placed without direct contact with the resident bone; primary stability was provided by an external device. An edentulous patient was restored with 5 endosseous titanium implants to support a mandibular fixed prosthesis. An implant placed in the right central incisor position was removed after 48 hours and replaced with a shorter and narrower implant without contact with resident bone. Thus, primary stability for the implant was provided by rigid fixation to the prosthesis rather than by bone anchorage. At recall examinations after 6 and 27 months, all implants, including the implant in the right central incisor position, showed clinical and radiographic signs of osseointegration. Resonance frequency analysis indicated acceptable stability and osseointegration for all implants. Observations of this patient suggest that implant osseointegration can be achieved by providing primary stability using a fixed complete denture. Primary bone anchorage/contact does not appear to be critical to the osseointegration process.     

Bodily distalization of molars with absolute anchorage

Palatal implants have been used over the last two decades to eliminate headgear wear and to establish stationary anchorage. In this case report, the stability of a palatal implant for distalization of molars bodily and for anchorage maintenance was assessed. The implant was a stepped screw titanium (4.5 mm diameter x 8 mm length), and it was placed in the palatal region for orthodontic purposes. A surgical template containing a metal drill housing was prepared. Angulation of the drill housing was controlled according to the radiologic tracing of the maxilla transferred to a plaster cast section in the paramedian plane. The implant was placed using a noninvasive technique (incision, flap, and suture elimination) and left transmucosally to facilitate the surgical procedure and to reduce the number of operations. The paramedian region was selected (1) to avoid the connective tissues of the palatine suture and (2) because it is considered to be a suitable host site for implant placement. After three months of healing, the implant was osseointegrated and orthodontic treatment was initiated. For molar distalization, the Keles Slider appliance was modified and, instead of a Nance button, a palatal implant was used for anchorage. The results showed that the molars were distalized bodily at five months, and no anchorage loss was observed. At the end of the treatment, the smile was improved, and an ideal Class I molar and canine relationship, an ideal overbite, and an ideal overjet were all achieved. In conclusion, palatal implants can be used effectively for anchorage maintenance and in space-gaining procedures. Use of a three-dimensional surgical template eliminated implant placement errors, reduced chair time, minimized trauma to the tissues, and enhanced osseointegration. This method can be used effectively to achieve distalization of molars bodily without anchorage loss.     

Initial stress differences between sliding and sectional mechanics with an endosseous implant as anchorage: a 3-dimensional finite element analysis

Endosseous implants have been used as orthodontic anchorage in recent years. A 3-dimensional mathematical model was constructed that uses the finite element method, which simulated an endosseous implant and an upper canine with its periodontal ligament and cortical and cancellous bone. Levels of initial stress were measured during 2 types of canine retraction mechanics (friction and frictionless). The lower magnitude and more uniform stresses in the implant and its cortical bone were found to have a moment-force ratio (M/F) of 6.1:1, whereas the canine and its supporting structures exerted a M/F ratio of 10.3:1. On the basis of these results, when the anchor unit is an endosseous implant, it seems better to use a precalibrated retraction system without friction (T-loop) where a low load-deflection curve would be generated.     

Bone‐to‐implant contact of orthodontic horizontal implants in humans subjected to loading

Implant‐based anchorage in orthodontics is increasingly obtaining significance. In this study, implants were temporarily inserted into the mid‐palatal and the mandibular retromolar areas in humans for orthodontic anchorage. Histological analysis of the implant‐bone interface was performed following the retrieval of implants which were subjected to prolonged oblique orthodontic loading. The results of the histomorphometric evaluation indicated that all the implants serving for orthodontic anchorage were well integrated into the bone despite the prolonged application of the orthodontic loading. Hence, it may be concluded that small‐size, one‐part transmucosal implants with a self-tapping thread and an SLA surface seemed to provide adequate anchorage for orthodontic therapy. Furthermore, the successful integration and the subsequent oblique loading of these orthodontic implants provide evidence that continuous forces in the order of magnitude of 2–6 N are compatible with the maintenance of osseointegration.     

The use of an osseointegrated implant for orthodontic anchorage to a Class II Div 1 malocclusion.

This case report describes the use of an osseointegrated implant to maximize anchorage in a 24-year-old female orthodontic patient with an Angle Class II, Division 1 malocclusion. Preadjusted edgewise appliance therapy was performed by extraction of only the maxillary first premolars. The osseointegrated implant was placed in the median-sagittal region of the hard palate for maximum orthodontic anchorage and connected to maxillary first molar bands via a transpalatal arch. Total treatment time was 2 years and 8 months. Cephalometric superimposition revealed the achievement of maximum molar anchorage in the maxilla, resulting in satisfactory occlusal and facial improvements. Histological analysis of the implant-bone interface demonstrated that the fixture was successfully osseointegrated. In conclusion, the osseointegrated implant placed in the median-sagittal palate was shown to be an effective orthodontic system that can be used clinically as a rigid intraoral anchorage.     

Orthodontic anchorage--Evidence-based evaluation of anchorage capacity and patients' perceptions

Orthodontic anchorage is the ability to resist unwanted reciprocal forces and reinforcement of anchorage by supplementary appliances, in or outside the mouth, is often needed to obtain successful results. In the last 10 years, interest in appliances that use implants has been growing. Successful orthodontic treatment demands effective methods and systematic evaluation of different treatment approaches is therefore essential. Several studies on the efficiency of various anchorage systems have been published, but a critical appraisal or interpretation of evidence that systematically considers validity, results, and relevance has not been made. Analysis of treatment modalities must also include patients' perceptions and potential side-effects. The overall aim of this thesis was to evaluate a new anchorage technique that incorporates osseointegration and compare it with conventional methods concerning effects on tooth movements in adolescents and their acceptance and experience of the additional surgical procedures that osseointegration involves. The following anchorage systems were analyzed: Onplant system, Orthosystem implant, headgear and transpalatal bar. This thesis was based on four studies: Paper I systematically reviewed the efficiency of orthodontic anchorage systems and interpreted the methodological quality of the selected studies from an evidence-based perspective. The literature search spanned January 1966 - December 2004 and was later extended to July 2007. Paper II, a methodological study involving 60 adolescent patients, examined the validity and reliability of a new questionnaire for assessing adolescent patients' perceptions of orthodontic treatment. The questionnaire was based on focus group interviews. Papers III and IV were randomized controlled trials involving 120 adolescent patients in orthodontic treatment. Paper III evaluated and compared adolescent patients' perceptions of premolar extractions and surgical placement of Onplants and Orthosystem implants. Paper IV compared anchorage capacities of the four systems. These conclusions were drawn: The scientific evidence, found in the review, was too weak to evaluate the efficiency of various anchorage systems (conventional and osseointegrated) during space closure after premolar extraction, and most studies have quality problems. Future randomized controlled trials are recommended. The new questionnaire, developed from focus group interviews, had overall acceptable to good reliability and high face validity. It can therefore be recommended for use in the assessment of adolescents' experiences of orthodontic treatment. Pain intensity after surgical placement of an Orthosystem implant was less than after Onplant installation and premolar extraction. Pain intensity after Onplant installation and premolar extractions were comparable. With respect to pain intensity, discomfort, and analgesic     

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.     

Clinical applications of mini-implants as orthodontic anchorage and the peri-implant tissue reaction upon loading

Orthodontic tooth treatment depends on anchorage for improved results.There are many different sources of orthodontic anchorage. Segments of teeth or the entire arch have been the most common type of orthodontic anchorage. But in challenging situations, orthodontists frequently need extra-dental supplements of anchorage such as headgear, face mask, and intermaxillary elastics. Most of them require the patient's compliance. Recently, temporary mini-implants placed within the bone tissue have been used as orthodontic anchorage. It has been proven in many studies and case reports that the mini-implant is a very reliable anchorage source clinically and histologically. The purpose of this article is to introduce the basic clinical application of mini-implants as orthodontic anchorage and to discuss basic concepts about the tissue reaction of peri-implant bone upon placement and loading either from orthodontic mechanics and/or function in the orthodontic treatment of the patients. It is possible for mini-implants to supply absolute anchorage even though they may move slightly within the bone tissue without losing clinical stability. The primary application of mini-implants as orthodontic anchorage will be cases that need absolute anchorage for desired tooth movement.     

Method for the placement of palatal implants

PURPOSE: Palatal implants have been used in the last 2 decades to eliminate headgear wear and to establish stationary anchorage. The aim of this investigation was to establish a method and easy protocol for palatal implant placement. MATERIALS AND METHODS: The study comprised 8 male and 15 female patients each having a 4.5 x 8-mm stepped screw titanium implant placed in the palatal region for orthodontic purposes. A surgical template containing metal drill housing was prepared. Angulation of the drill housing was controlled according to the radiologic tracing of the maxilla transferred to a plaster cast section in the paramedian plane. Implants were placed using a noninvasive technique (incision, flap, and suture elimination) and left transmucosally to facilitate the surgical procedure and reduce operations. The paramedian region was selected so as to avoid connective tissues of the palatine suture and because it was considered to be a suitable host site for implant placement. RESULTS: After 3 months of healing, all implants were osseointegrated and no implant was lost throughout the orthodontic treatment. DISCUSSION: Palatal implants can be used effectively for anchorage maintenance and space-gaining procedures. CONCLUSION: Usage of a 3-dimensional surgical template eliminated faulty implant placement, reduced chair time, and minimized trauma to the tissues while enhancing osseointegration.     

The use of miniscrew implants for temporary skeletal anchorage in orthodontics: a comprehensive review

Though not a novel therapeutic concept, the use of miniscrew implants to obtain absolute anchorage has recently become very popular in clinical orthodontic approaches. The mode of anchorage facilitated by these implant systems has a unique characteristic owing to their temporary use, which results in a transient, albeit absolute anchorage. The foregoing properties together with the recently achieved simple application of these screws have increased their popularity, establishing them as a necessary treatment option in complex cases that would have otherwise been impossible to treat. The aim of this comprehensive review is to present and discuss the development, clinical use, benefits, and drawbacks of the miniscrew implants used to obtain a temporary but absolute/skeletal anchorage for orthodontic applications. Topics to be discussed include classification, types and properties (e.g., biocompatibility, osseointegration, types of anchorage, screw head, and thread design), clinical applications, site and placement method selection, clinical procedures for implant insertion, and loading and removal processes. Lastly, the potential complications and the advantages and disadvantages accompanying their use are presented.     

Immediate function of cortically anchored disk-design implants without bone augmentation in moderately to severely resorbed completely edentulous maxillae.

The completely edentulous maxilla remains a challenge in implant dentistry. Conventional two-stage surgical techniques require two independent invasive surgeries separated by a 5-6-month healing period. In addition, an increased risk of trauma to the implant-bone interface may be caused by a removable transitional complete denture during the interim submerged period, which can compromise implant success or increase crestal bone loss around the implants during initial bone healing. The purpose of this clinical trial was to evaluate the safety and efficacy of immediately loading a fixed implant-supported prosthesis without bone augmentation in moderately to severely resorbed, completely edentulous maxillae. Over a 41-month period, 783 titanium implants (627 laterally inserted disk implants, with or without 156 axially inserted Structure implants) were placed in 72 consecutive patients with completely edentulous maxillae using an immediate loading protocol. After 6 months of function, the fixed restorations were removed and each implant status was verified using radiographs, Periotest evaluations, clinical osseointegration criteria, and torque testing at 20 N-cm. Six months postoperatively, 98% of the implants were radiologically and clinically osseointegrated. Fifty-six gold screws (7%) required retightening after 10 months, but no screw fractures occurred during this study period. The postrestorative follow-up of these patients ranged from 6 to 48 months. As of this report, all of the fixed prostheses remain functional, and no additional implants have been lost. This clinical trial demonstrates that immediate loading of nonsubmerged, laterally inserted disk-design implants may provide adequate primary anchorage and longterm osseointegration in completely edentulous maxillae. The initial multicortical anchorage afforded by the disk-design implant in this study, coupled with biomechanical splinting of the disks (sometimes with more traditional root-form design implants) using a rigid prosthesis, permits a one-stage predictable implant procedure offering rapid restoration of patients to masticatory function.     

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.