Orthodontic anchorage: a systematic review

The aim of this systematic review was to examine, in an evidence-based way, what kind of orthodontic anchorage systems/applications are evaluated and their effectiveness. A literature survey from the Pub Med and Cochrane databases covering the period from January 1966 to December 2004 was performed. Randomized controlled trials (RCT), prospective and retrospective controlled studies, and clinical trials comparing at least two anchorage situations were included. Two reviewers selected and extracted the data independently and also assessed the quality of the retrieved studies. The search strategy resulted in 494 articles, of which 14 met the inclusion criteria. Two main anchorage situations were identified: anchorage of molars during space closure after premolar extractions and anchorage loss in the incisor or premolar region (or both) during molar distalization. Because of contradictory results and the vast heterogeneity in study methods, the scientific evidence was too weak to evaluate anchorage efficiency during space closure. Intraoral molar distalization leads to anchorage loss in various amounts depending on the choice of distalization unit. Most of the studies had serious problems with small sample size, confounding factors, lack of method error analysis, and no blinding in measurements. To obtain reliable scientific evidence, controlled RCT's with sufficient sample sizes are needed to determine which anchorage system is the most effective in the respective anchorage situation. Further studies should also consider patient acceptance and cost analysis as well as implants as anchorage.     

Orthodontic implants as anchorage appliances for unilateral mesialization: a case report.

Space closure from distal to mesial is one of the most difficult orthodontic tasks. Toothborne anchorage limits the scale of tooth movement. Extraoral or intraoral appliances are used especially for unilateral space closure. As an alternative to conventional mesialization appliances, osseointegrated implants may be used for maximum anchorage in orthodontic treatment. Temporary implants inserted in the palatal suture are most common in maxillary treatment. In the case presented, temporary implants were placed in the palatal bone of a 17-year-old male patient with hypodontia of the mandibular central incisors and second premolars and the maxillary left second premolar for mesialization of the molars. Slight irritations of the tongue were registered in the first 2 weeks of use of the palatal implant. There were no other effects during treatment.     

Orthodontic anchorage with specific fixtures: related study analysis.

The purpose of this report is to systematically review the relevant major studies published between 1970 and 2000 related to the use of implants for orthodontic anchorage. Analysis of the literature is divided into specific topics: materials, size and shape of fixtures, biomechanics, healing and loading times, forces used, surgery, and criteria for success. Two subjects previously given little consideration in the discussion of implants-the psychological aspects of the doctor-patient relationship and the medical-legal implications of implantology for orthodontic purposes-are briefly addressed.     

Use of a 2.0-mm locking plate/screw system for mandibular fracture surgery.

PURPOSE: In this study, we examined the use of a 2.0-mm locking bone plate/screw system in mandibular surgery. PATIENTS AND METHODS: All patients who were treated with a 2.0-mm locking bone plate/screw system during an 8-month period for fractures of the mandible or other defects of the mandible were prospectively studied. Ease of use of locking plate/screw system, characteristics of the fractures and defects, and complications were tabulated. RESULTS: A total of 80 fractures in 59 patients were treated with the 2.0-mm locking plate/screw system. One hundred two 2.0-mm locking plates were applied to the 80 fractures; 58 fractures received 1 plate and 22 fractures received 2 plates. There were no intraoperative difficulties associated with their application. Fracture reductions were considered to be excellent in all cases. At the latest follow-up, all fractures had healed, but 2 patients had slight malocclusions. Six patients developed postsurgical infections. Only 1 patient required hospitalization for treatment of the infection; all others were managed in the outpatient clinic. Four patients required removal of their plates for varying reasons. CONCLUSIONS: The use of a 2.0-mm locking plate/screw system was found to be simple and to provide sound fixation in all cases.     

Intercortical osteotomy with fixation using a locking system

In 12 patients with lower macrognathia we have applied a technique allowing to prevent the postsurgical recidives of the jaw deformation. The locking system allowed to ensure the stability of osteal fragments in sagittal plane, increase firmness and solidity of osteal suture fixation in the cases of bad intraoral supplementary fixation.     

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     

AO self-drilling and self-tapping screws in rat calvarial bone: an ultrastructural study of the implant interface.

PURPOSE: The purpose of the present study was to compare the bone-to-screw interface of both AO self-drilling screws (SDSs) and self-tapping screws (STSs) using scanning electron microscopy. MATERIALS AND METHODS: The calvaria from Sprague-Dawley rats were harvested, and the periosteum was removed. The samples were stored in saline until use. AO STSs and SDSs were then inserted into the outer surface of the calvaria without irrigation. All screws were 4 mm in length and were inserted until their tips protruded to the endosteal side. A total of 6 screws, 3 of each type, were placed. The dimensions of the screws were 1.3, 1.5, and 2.0 mm. All STSs were placed with an appropriately sized predrilled hole. Samples were then examined and digitally photographed using scanning electron microscopy. RESULTS: No damage was noted to any of the implants (STSs or SDSs). Excellent adaptation of the STSs to host bone was observed for all specimens. On the other hand, the endosteal surface of the SDSs demonstrated large voids adjacent to the screw threads at the interface. These appeared to represent microfractures of the bone at the bone-implant interface. CONCLUSIONS: These data suggest a greater amount of bone damage during placement of the SDSs compared with the STSs. These results point to the need for further investigation into the use of SDSs in clinical practice.     

Skeletal and dental effects of molar distalization using a modified palatal anchorage plate in adolescents

Objective:To evaluate and compare skeletal effects and the amount of molar distalization in maxilla using modified palatal anchorage plate (MPAP) vs headgear appliances in adolescent patients.Materials and Methods:Pre- and posttreatment lateral cephalograms of 45 Class II malocclusion patients were analyzed; 24 were treated with MPAP appliances (age, 12.4 years) and 21 with headgear (age, 12.1 years). Fixed orthodontic treatment started with the distalization process in both groups. Thirty-two variables were measured and compared between both groups using multivariate analysis of covariates.Results:There was no significant main effect of the appliance type on the treatment results (P  =  .063). Also, there was no significant main effect of the appliance type on both pre- and posttreatment comparisons (P  =  .0198 and .135, respectively). The MPAP and headgear groups showed significant distalization of maxillary first molars (3.06 ± 0.54 mm and 1.8 ± 0.58 mm, respectively; P < .001). Sagittal skeletal maxillomandibular differences were improved after treatment (P < .001), with no significant differences between the two groups. No significant difference in treatment duration was found between the groups.Conclusions:The MPAP showed a significant skeletal effect on the maxilla. Both MPAP and headgear resulted in distalization of maxillary first molars. Therefore, it is recommended that clinicians consider the application of MPAP, especially in noncompliant Class II patients.     

Immediate and late inflammatory and bone healing response post implantation of self-tapping and self-drilling osteosynthesis screws

The aim of this study was to comparatively analyse osseointegration after the implantation of self-tapping screws (STS) and self-drilling screws (SDS). Thus, 24 four-month-old male Wistar rats, received SDS and STS screws in their left and right tibias, respectively. Sample collection was performed immediately at 0 hours (0h), two, seven, and 21 days after implantation (2d, 7d, 21d). Samples from immediately and 21 days after were analysed by micro computed tomography (MicroCT). All time points were evaluated by histology (Haematoxylin and Eoisin and Goldner's Trichrome) and immunohistochemistry for tartrate-acid resistant phosphatase positive (TRAP+) osteoclasts. MicroCT images revealed an intimate contact between bone and each type of screw at 0h. However, SDS group presented decreased bone volume (BV, mm³) at 21 days in comparison with STS. Both SDS and STS post implantation presented areas of suitable new bone formation surrounding screw threads from seven days, and inflammation decreased from two to 21 days. Also, TRAP+ osteoclasts were mainly identified at seven days in both STS and SDS groups, particularly surrounding areas of pressure, with significant differences between groups. In conclusion, differences in shape and insertion technique for SDS and STS screws did not affect immediate and late inflammatory and bone healing response post implantation in this animal model. Both osteosynthesis screws allowed satisfactory post-surgical outcomes.     

Comparative evaluation of 2.0-mm locking plate system vs 2.0-mm nonlocking plate system for mandibular fracture: a prospective randomized study

This study evaluated the efficacy of a 2.0-mm locking plate/screw system compared with a 2.0-mm non-locking plate/screw system in mandibular fractures. A prospective randomized clinical trial was conducted. Patients were randomly assigned to receive 2.0-mm locking plates (group A) or 2.0-mm nonlocking plates (group B). All patients were followed up for 12 weeks postoperatively. Complications were analysed according to the type of plate used and the site of fracture. Fifty patients with 76 fractures met the inclusion criteria. Thirty-six fracture sites were treated with 2.0-mm locking plates and 40 with 2.0-mm nonlocking plates. The number of patients requiring postoperative maxillomandibular fixation was significantly higher in group B (p < 0.01); seven complications occurred representing 9% of the total. Two complications occurred in the locking group and five in the nonlocking group with complication rates equalling 6% and 13%, respectively. When comparing the overall complication rates according to plates used, the χ² test showed no statistically significant difference between the locking and nonlocking plates (p > 0.05). In conclusion, mandible fractures treated with 2.0-mm locking plates and 2.0-mm nonlocking plates present similar short-term complication rates.     

Intermaxillary fixation using screws. Report of a technique.

A technique of intermaxillary fixation using screws anchored in the maxilla and mandible has been described. AO (Synthes) screws with a diameter of 3.5 mm and 12 mm to 16 mm in length were inserted at the antero-lateral surface of the maxilla and the buccal surface of the mandible. This technique is particularly suitable for mandibular fractures in denture wearing patients.     

Orthodontic bone screws: A quick update and its promising future

Orthodontic bone screws (OBSs) provide intraoral anchorage by penetrating oral mucosa and seating firmly in basilar bone (BB). Retromolar (prosthetic-type) implants introduced the extra-alveolar (E-A) concept for BB anchorage to move teeth throughout the alveolar process, but the clinical procedures were complex and expensive. Titanium alloy (Ti) miniscrews placed in inter-radicular (I-R) alveolar bone are more convenient and provide some tooth movement potential, but multiple screws are usually required and the devices often interfere with the path of tooth movement. The advantages of BB anchorage and the convenience of miniscrew are combined into the E-A OBS system. These miniscrews are relatively large in diameter (2 mm), and strong (stainless steel), which are placed intraorally in the BB of the infra-zygomatic crest (IZC) and mandibular buccal shelf (MBS). E-A OBSs provide osseous anchorage to retract the dentition and/or rotate either arch. Recovery of impactions is effectively managed with lever arm springs anchored with IZC or MBS bone screws. An emerging frontier is BB anchorage for correcting severe malocclusions with clear aligners. Since the osseous-anchored mechanics are complementary, fixed appliances and clear aligners can be used individually or in tandem to resolve a broad variety of malocclusions. This report summarizes current concepts for conservatively managing complex malocclusions such as severe crowding, skeletal discrepancies, asymmetries and impactions with the OBS system.     

Stability of the chin after advancement genioplasty using absorbable plate and screws with template devices

PurposeThe purpose of this study was to compare the stability of the chin between absorbable plate and screws with a template device and titanium plate after advancement genioplasty in class II patients.Patients and methodsThe subjects consisted of 22 Japanese class II patients who underwent genioplasty advancement in combination with bi-maxillary surgery. After genioplasty horizontal osteotomy, the template plate and screws were fixed at the central region of the chin temporarily. Then, two absorbable bi-cortical screws (uncalcined and unsintered hydroxyapatite and poly-l-lactic acid: uHA/PLLA) were used and fixed bilaterally. After removal of the template plate and screws, one absorbable plate and screws were added to fix the segment in the advancement genioplasty (n = 14). The remaining 8 patients underwent genioplasty advancement surgery with the conventional titanium plate.For all patients, lateral cephalograms were obtained pre- and immediately after surgery and at 1 year after surgery. Change in the Pogonion (Pog) and Menton (Me) points and the corresponding soft tissue points (PogS and MeS) were evaluated.ResultsAlthough there were no significant differences in the change from before to immediately after surgery between the absorbable and titanium groups, there were significant differences in the Pog (Y) (P = 0.0379) and PogS (Y) (P = 0.0379) from immediately after surgery to after 1 year between both groups.ConclusionThis study shows that predicted advancement of the chin in the absorbable group could be achieved by using a template and screws, and likewise in the titanium group. However, this study suggested that vertical relapse to the inferior site or resorption at the antero-superior edge of the segment could occur in the absorbable group.