Maxillary Posterior Intrusion Research Articles

Efficacy of clear aligner wear protocols in orthodontic tooth movement-a systematic review.

Different expedited aligner wear protocols are currently in practice. This review was undertaken to systematically appraise the available evidence on the comparative efficacy of orthodontic tooth movement (OTM) across the different wear protocols. Two assessors conducted comprehensive searches of electronic databases, including MEDLINE (via PubMed), Scopus, Embase, Web of Science, Google Scholar, Directory of Open Access Journals, Cochrane Library, OpenGrey, and Clinical Trial Registry, till 18 February 2024. Titles and abstracts were independently screened. Prospective or retrospective studies comparing expedited wear protocols with the conventional 14-day protocol were included. A pre-piloted data extraction form was used. Risk of bias (RoB) assessment employed the Cochrane RoB 2.0 tool for randomized-controlled trials (RCTs) and the Newcastle-Ottawa scale for non-RCTs. The quality of evidence was evaluated using the Grading of Recommendations, Assessment, Development, and Evaluation Pro tool. Six studies, including 3 RCTs and 3 non-RCTs, were selected from 9076 records. Four studies (two RCTs and two retrospective cohort) found no statistically significant difference (P > 0.05) in the OTM efficacy between expedited and conventional protocols. Two studies (one RCT and one prospective cohort) found greater efficacy (P < 0.05) with the 14-day protocol, with the RCT reporting greater efficacy for certain movements, such as maxillary posterior intrusion, maxillary posterior distal tipping and buccal torquing, and mandibular posterior intrusion and extrusion. One RCT reported statistically insignificant difference (P > 0.05) in pain perception between the 10-day and 14-day protocols. Two studies demonstrated low RoB, two moderate, and two high RoB. The evidence level was very-low for OTM efficacy and high for pain perception. Meta-analysis was precluded due to significant heterogeneity among the studies. Within the limitations of the study, the 7-day, 10-day, and 14-day protocols did not show any significant difference in OTM efficacy, except for certain movements that exhibited superior outcomes with the 14-day wear. Hence, a 'hybrid aligner-wear protocol', based on clinical judgement, might serve a better alternative in complex situations. PROSPERO CRD42021288179.

An Orthodontic Treatment Case of a TMD Patient with Maxillary Posterior Intrusion Using TSADs

The orthodontic treatment of patients having temporomandibular disorders are some of the most complicated cases to treat. The positions of the mandibular condyles are often unstable, which means clinicians find it difficult to have definite criteria for making an accurate and reliable orthodontic diagnosis. This article reports the orthodontic treatment of a patient showing skeletal Class II and temporomandibular disorders with condylar resorption. To stabilize her condylar position and to relieve her symptoms in the temporomandibular joint, a stabilization splint was used before orthodontic tooth movement. After the splint therapy, the patient exhibited significantly increased open bite and a more severe Class II occlusal relationship as her mandibular condyles were seated anteriorly and superiorly in the articular fossae. The occlusion and facial esthetics of the patient were improved by orthodontic camouflage treatment with the proper use of temporary skeletal anchorage devices and treatment mechanics.

Cephalometric evaluation of intrusion of maxillary posterior teeth by miniscrews in the treatment of open bite

The objective of this research was to investigate the effectiveness of orthodontic miniscrews for skeletal anchorage during anterior open bite treatment using cephalometric radiographs. This study sample included 20 patients (mean age, 14.71; standard deviation, 1.77) with an anterior open bite. A total of 250g of force was applied using elastic chains with anchorage from palatal miniscrew to an occlusal splint covering the posterior maxillary teeth. Cephalograms were obtained at the beginning of the treatment when the appliance was first applied and at the 8-month visit when treatment was completed. Paired t tests were used to identify statistically significant differences between initial and final measurements of skeletal and dental parameters. A decrease of 2.72±1.90° in the SN-GoGn angle and 3.63±1.87mm in the anterior height (N-Me) parameter in the cephalometric evaluations indicated a significant improvement of vertically increased facial dimensions, with the intrusion of the maxillary posterior teeth (P<0.05). Anterior rotation of the mandible was determined by a 1.76±1.09° increase in the SNB angle and a 1.86±0.90° decrease in the ANB angle (P<0.05). Reductions in the open bite amount by 5.8±0.90mm, Mx6-SN by 4.00±1.01mm, and Mx6-PP by 4.01±1.00mm were indicative of significant intrusion in the maxillary posterior teeth (P<0.05). The present study confirmed that palatal miniscrew and maxillary occlusal splint caused intrusion of the maxillary posterior teeth, a decrease in the anterior open bite, and mandibular advancement, with anterior rotation after the maxillary posterior intrusion. We concluded that the treatment method in our study was appropriate for patients with Class I and mild Class II malocclusions and open bite anomalies.

Maxillary posterior intrusion with corticotomy-assisted approaches with zygomatic anchorage\u2014a finite element stress analysis

BackgroundAnterior open bite is one of the most difficult malocclusions to treat and maintain in orthodontics. An effective treatment approach to correct anterior open bite is the intrusion of maxillary posterior teeth. The aim of this study was to evaluate the effects of corticotomy-assisted posterior maxillary intrusion with zygomatic anchorage by using finite element stress analysis.MethodsAn acrylic bite block on the posterior teeth including two transpalatal arches were modeled and 1.96 N intrusive force was loaded. Three scenarios were set, first with no subapical corticotomy, second with buccal, and third with both buccal and palatal corticotomies. The stress distributions along the cortical, cancellous bone surfaces, and dental structures were assessed by finite element stress analysis.ResultsStress distributions over cortical and cancellous bones were commonly located at the inferior curvature of the zygomatic buttress area and posterior teeth for all scenarios. Stress values above the apices of anchor teeth were decreased for both corticotomy scenarios. Increased stress distributions were observed in cancellous bone around corticotomy regions. Despite the acrylic appliance and transpalatal arches, the stresses along the posterior teeth were not uniform. The apical third of the first molar mesiobuccal apex showed the highest stress values in all scenarios.ConclusionsCorticotomy-assistance effected biomechanical responses of dentoalveolar structures during maxillary posterior intrusion. There was no apparent difference for the stress levels of the root apices between corticotomy scenarios, pointing out that only buccal corticotomy may be a better option in corticotomy-assisted maxillary intrusion.

Long-term stability of soft tissue changes in anterior open bite adults treated with zygomatic miniplate-anchored maxillary posterior intrusion.

To evaluate soft tissue changes and their long-term stability in skeletal anterior open bite adults treated by maxillary posterior teeth intrusion using zygomatic miniplates and premolar extractions. Lateral cephalograms of 26 patients were taken at pretreatment (T1), posttreatment (T2), 1 year posttreatment (T3), and 4 years posttreatment (T4). At the end of treatment, the soft tissue facial height and profile convexity were reduced. The lips increased in length and thickness, with backward movement of the upper lip and forward movement of the lower lip. The total relapse rate ranged from 20.2% to 31.1%. At 4 years posttreatment, 68.9% to 79.8% of the soft tissue treatment effects were stable. The changes in the first year posttreatment accounted for approximately 70% of the total relapse. Soft tissue changes following maxillary posterior teeth intrusion with zygomatic miniplates and premolar extractions appear to be stable 4 years after treatment.

Evaluation of stress patterns on maxillary posterior segment when intruded with mini implant anchorage: A three-dimensional finite element study

Introduction The aim of this study is to evaluate stress and displacement effects of maxillary posterior intrusion mechanics with mini-implant anchorage by using finite element method. Materials and Methods A computer stimulation of three-dimensional model maxilla with all teeth, PDL, bone, mini-implants, brackets, arch wire, force element, and transpalatal arch was constructed on the basis of average anatomic morphology. Finite element analysis was done to evaluate the amount of stress and its distribution during orthodontic intrusive force. Results Increased Von Mises stress values were observed in mesio-cervical region of first molar. The middle third of second premolar and second molar and regions adjacent to force application sites also showed relatively high stress values. Minimum stress values were observed in apical region of first premolar as it is away from force application. Conclusion Using three mini-implant and transpalatal arches, this study demonstrates that significant amount of true intrusion of maxillary molars could be obtained with lesser concentration of stresses in the apical area recorded.

Maxillary posterior intrusion mechanics with mini-implant anchorage evaluated with the finite element method

The goal of this study was to evaluate the effects of 3 maxillary posterior intrusion mechanics with mini-implant anchorage by using the finite element method. Finite element models were generated by assembling the images obtained by computed tomography and a laser surface scanner. For each posterior dental segment, a 300-g force was applied and distributed to the mini-implants in proportion to their calculated root surface areas. The most balanced intrusion and the most uniform stress distribution were obtained by concurrent force applications from the vestibular and palatinal sides. In the models with transpalatal arches and buccal force application, vestibular tipping movement and overall stress values were prominent. In all models, increased stress values were identified at the apical region of the first premolar roots and at the apical region of the first molar mesial root. The results of this study suggest that the apical region of the first premolar roots and the apical region of the first molar mesial root should be considered to be prone to resorption during posterior intrusion treatment. Posterior intrusion systems with force application from counterbalancing sites lead to a more uniform stress distribution and balanced intrusion than the mechanics with a transpalatal arch. For a balanced intrusion, root surface areas should be considered when determining the appropriate forces.

Supra-apical posterior ostectomy and zygomatic miniplate anchorage—a new approach to treat severe skeletal anterior open bites

Background: Correction of severe anterior open bites is impossible with traditional orthodontic treatment and a conventional Le Fort I impaction osteotomy is often the only alternative. Skeletal anchorage is becoming a popular therapeutic tool in orthodontics and miniplates in the zygomatic buttress area can serve as anchorage for maxillary posterior intrusion.