Intrusion Of Maxillary Posterior Teeth Research Articles

Nonsurgical correction of occlusal canting using temporary anchorage devices: A systematic review

ObjectiveThe recent development of temporary anchorage devices (TADs) allows orthodontic canting correction by selective intrusion of the molars. The purpose of this study was to review the treatment strategy and outcomes after orthodontic correction of occlusal canting using the TADs based on published literature including the case reports. Materials and methodsA systematic review of published English-language human clinical studies was conducted by electronic search of PubMed, Embase & Medline, and Scopus reviews up to Dec 2023. For inclusion, reports required documentation of subject demographic characteristics; location or type of TADs; diagnosis; presence of maxillary occlusal canting (MOC); and treatment outcomes (MOC correction). Studies were excluded if they involved orthognathic surgery to correct MOC. Critical appraisal for all included studies were conducted with the case reports/case series appraisal checklist of the Joanna Briggs Institute (JBI). The current study was registered in PROSPERO (CRD42021226432). ResultsThe search identified 260 reports and a total of 33 case reports met inclusion criteria with 46 individual patient cases. The results reported that occlusal canting could be resolved by unilateral intrusion of maxillary posterior teeth using TADs. The reported the amount of maxillary molar intrusion ranged from 1 mm to 4.8 mm. However, there were fundamental limitations in study subjects, paucity of data regarding the long-term stability, lack of standardization in intrusion mechanics, and variations in TAD devices. ConclusionsAlthough the previous reports mentioned that orthodontic canting correction with TADs could avoid maxillary surgery or orthognathic surgery itself, it cannot be concluded that non-surgical correction of occlusal canting can be comparable to surgical treatment. Further comparative investigation between surgical and nonsurgical canting correction is needed to clarify whether orthodontic intrusion can be an alternative to surgical canting correction in terms of efficacy and stability.

Intrusion of Maxillary Posterior Teeth by Skeletal Anchorage: A Systematic Review and Case Report with Thin Alveolar Biotype.

This study aimed to review the literature related to the intrusion of maxillary posterior teeth in subjects needing pre-prosthetic restoration or orthodontic treatment due to anterior open bite, and to report a thin alveolar biotype case needing a pre-prosthetic intrusion of maxillary teeth by introducing a novel, personalized method of intrusion measurement. An electronic search was conducted between February 2022 and March 2022 in the following databases: PubMed, Scopus, Embase, Web of Science, and Lilacs; the terms “tooth movement techniques”, “orthodontic anchorage procedures”, “tooth intrusion”, “intrusion”, “molar”, “premolar”, and “human” were surveyed. Eighteen articles were included in this review; the mean amount of intrusion ranged from between 2.1 ± 0.9 mm and 4.57 ± 0.98 mm (being mostly 2–3 mm). The intrusion force varied between 100 and 500 g; 10 articles reported miniscrews (MS), 7 reported zygomatic plates (ZP), and 1 publication reported both anchorage types. The average treatment time was 6.9 months for MS and 7.9 months for ZP. Levelling the occlusal plane by intrusion of the upper posterior teeth can be achieved by skeletal anchorage. The stability of the obtained results, shortening treatment time, and controlling treatment outcome are the main goals for a complex surgical and orthodontic treatment approach.

Orthodontic Management of Severe Dentoalveolar Collapse with Miniscrew-Assisted TMA Cantilever Springs and Bite Blocks

Introduction: Management of mutilated cases is challenging, and adult patients often require orthodontic correction of occlusion before prosthetic replacement of missing teeth. Objective: To highlight the novel, simple, hygienic, and efficient miniscrew-supported Beta titanium molybdenum alloy (TMA) cantilever spring for uprighting severe mesially tipped molars for interdisciplinary treatment. Diagnosis and Treatment: A 23-year-old male patient presented with skeletal Class I relation, average growth pattern, Class II Division 1 malocclusion with dentoalveolar collapse, crowding, multiple missing, supraerupted teeth, and severe mesially tipped mandibular third molars. MBT appliance with 0.022˝ slot was used to achieve the objectives. 38 and 48 were uprighted and protracted with miniscrew implant-supported TMA cantilever springs to substitute 37 and 47. Mild intrusion of maxillary posterior teeth was done with acrylic bite blocks and transpalatal arch (TPA), followed by prosthetic replacement of missing teeth. Results: The patient had a consonant smile arc and a pleasing soft tissue profile. 38 and 48 were uprighted and protracted with good vertical control, and the mesial pockets were eliminated. 17 and 27 were intruded, and group function occlusion was established. Class I canine relationship, normal overjet, and overbite were achieved. Conclusion: Miniscrew supported TMA cantilevers are efficient for uprighting of severely tipped 38 and 48 without extrusion, unlike the conventional mechanics. 18, 28, 38 and 48 with good root forms can be protracted and substituted as 17, 27, 37 and 47 respectively to minimize or eliminate prosthetic rehabilitation.

A surgery-first approach using single-jaw rotational mandibular setback in low-angle mandibular prognathism

For the treatment of low-angle mandibular prognathism, rotational mandibular setback surgery is usually performed with Le Fort I maxillary osteotomy to rotate the maxillomandibular complex simultaneously. However, this maxillary surgery can be replaced with the orthodontic intrusion of maxillary posterior teeth. Single-jaw rotational mandibular setback surgery can be done with a surgery-first approach by planning orthodontic rotation of the maxillary occlusal plane with the simulation of the postsurgical forward mandibular rotation. This case report describes this approach applied to a 19-year-old female patient with low-angle mandibular prognathism but without maxillary deficiency. A Class II open bite was formed by the rotational setback surgery. During postsurgical orthodontic treatment, the maxillary total arch was distalized with maxillary molar intrusion using palatal mini-implants and lever. This case report demonstrates that orthodontic rotation of the maxillary occlusal plane and simulation of mandibular rotation can replace maxillary surgery and enable single-jaw rotational mandibular setback surgery with a surgery-first approach.

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.

Correction of open bite with temporary anchorage device-supported intrusion

This case report describes the use of temporary anchorage device (TAD)-supported molar intrusion to correct anterior open bite and achieve overjet correction. A 13-year-old female presented with a Class II skeletal profile, with increased overjet and anterior open bite. She was treated with a combination of intrusion of the posterior teeth and extrusion of anterior teeth. The intrusion of maxillary posterior teeth was done with a palatal TAD and a transpalatal arch on the upper first molars to control the transverse dimension. The patient’s mandibular plane angle was maintained with this treatment approach.

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.

Effect of premolar extraction and incisor retraction on the soft tissue in adult skeletal open bite subjects with miniplate anchored intrusion of maxillary posterior teeth

Objective: This study was conducted to determine the effect of premolar extraction and incisor retraction on the soft tissue profile of skeletal open bite adults following maxillary posterior teeth intrusion. Materials and Methods: Lateral cephalometric radiographs of 28 adults with skeletal open bite (age = 22.6 ± 2.1 years) were taken following molar intrusion with zygomatic miniplate skeletal anchorage and after four first premolars extraction. Several soft tissue variables were measured. Correlations, mean ratios and regression equations between the change in lip position and incisor retraction were calculated. Results:Both the upper and lower lips moved backwards by 3.46 mm ± 0.84 mm (P ≤0.01) and 0.87 mm ± 0.23 mm (P ≤ 0.05) respectively, with a significant reduction in the angle of convexity by 1.36° ± 0.24° (P ≤ 0.05). Strong correlations were found between the amount of upper incisor retraction and backward movement of the upper lip with a mean ratio of 1.04:1 (r = 0.812, P ≤ 0.01) and with the reduction of soft tissue convexity angle with a mean ratio of 2.65:1 (r = 0.814, P ≤ 0.01) and between the lower incisor retraction and backward movement of the lower lip with a mean ratio of 0.76:1 (r = 0.802, P ≤ 0.01). Conclusion: The pattern of change in soft tissue profile in this study was similar to studies of premolar extraction without prior molar intrusion. However, the ratio of change of upper lip position relative to the upper incisor retraction was higher compared to ratios reported in the literature which may be attributed to the underlying long face skeletal pattern.

Prediction of changes due to mandibular autorotation following miniplate-anchored intrusion of maxillary posterior teeth in open bite cases

BackgroundPrediction of the treatment outcome of various orthodontic procedures is an essential part of treatment planning. Using skeletal anchorage for intrusion of posterior teeth is a relatively novel procedure for the treatment of anterior open bite in long-faced subjects.MethodsData were analyzed from lateral cephalometric radiographs of a cohort of 28 open bite adult subjects treated with intrusion of the maxillary posterior segment with zygomatic miniplate anchorage. Mean ratios and regression equations were calculated for selected variables before and after intrusion.ResultsRelative to molar intrusion, there was approximately 100% vertical change of the hard and soft tissue mention and 80% horizontal change of the hard and soft tissue pogonion. The overbite deepened two folds with 60% increase in overjet. The lower lip moved forward about 80% of the molar intrusion. Hard tissue pogonion and mention showed the strongest correlations with molar intrusion. There was a general agreement between regression equations and mean ratios at 3 mm molar intrusion.ConclusionsThis study attempted to provide the clinician with a tool to predict the changes in key treatment variables following skeletally anchored maxillary molar intrusion and autorotation of the mandible.

Biochemical and Clinical Assessments of Segmental Maxillary Posterior Tooth Intrusion.

Objective. To compare chondroitin sulphate (CS) levels around maxillary second premolars, first molars, and second molars between the unloaded and the loaded periods and to measure the rates of intrusion of maxillary posterior teeth during segmental posterior tooth intrusion. Materials and Methods. In this prospective clinical study, 105 teeth (from 15 patients exhibiting anterior open bite and requiring maxillary posterior tooth intrusion) were studied. Competitive ELISA was used to detect CS levels. Dental casts (during the unloaded and loaded periods) were scanned, and posterior tooth intrusion distances were measured. Results. During the unloaded period, the median CS levels around maxillary second premolars, first molars, second molars (experimental teeth), and mandibular first molars (negative control) were 0.006, 0.055, 0.056, and 0.012 and during the loaded period were 2.592, 5.738, 4.727, and 0.163 ng/μg of total protein, respectively. The median CS levels around experimental teeth were significantly elevated during the loaded period. The mean rates of maxillary second premolar and first and second molar intrusion were 0.72, 0.58, and 0.40 mm/12 weeks, respectively. Conclusions. Biochemical and clinical assessments suggested that the segmental posterior tooth intrusion treatment modality with 50 g of vertical force per side was sufficient. Trial Registration. The study is registered as TCTR20170206006.

Outcomes and stability in patients with anterior open bite and long anterior face height treated with temporary anchorage devices and a maxillary intrusion splint

Temporary skeletal anchorage devices now offer the possibility of closing anterior open bites and decreasing anterior face height by intruding maxillary posterior teeth, but data for treatment outcomes are lacking. This article presents outcomes and posttreatment changes for consecutive patients treated with a standardized technique. The sample included 33 consecutive patients who had intrusion of maxillary posterior teeth with a maxillary occlusal splint and nickel-titanium coil springs to temporary anchorage devices in the zygomatic buttress area, buccal and apical to the maxillary molars. Of this group, 30 had adequate cephalograms available for the period of treatment, 27 had cephalograms including 1-year posttreatment, and 25 had cephalograms from 2years or longer. During splint therapy, the mean molar intrusion was 2.3mm. The mean decrease in anterior face height was 1.6mm, less than expected because of a 0.6-mm mean eruption of the mandibular molars. During the postintrusion orthodontics, the mean change in maxillary molar position was a 0.2-mm extrusion, and there was a mean 0.5-mm increase in face height. Positive overbite was maintained in all patients, with a slight elongation (<2mm) of the incisors contributing to this. During the 1year of posttreatment retention, the mean changes were a further eruption of 0.5mm of the maxillary molars, whereas the mandibular molars intruded by 0.6mm, and there was a small decrease in anterior face height. Changes beyond 1year posttreatment were small and attributable to growth rather than relapse in tooth positions. Intrusion of the maxillary posterior teeth can give satisfactory correction of moderately severe anterior open bites, but 0.5 to 1.5mm of reeruption of these teeth is likely to occur. Controlling the vertical position of the mandibular molars so that they do not erupt as the maxillary teeth are intruded is important in obtaining a decrease in face height.

The short-term skeleto-dental effects of a new spring for the intrusion of maxillary posterior teeth in open bite patients.

BackgroundThe technology surrounding temporary skeletal anchorage devices has improved in leaps and bounds. However, no specific auxiliary exists for the intrusion of molars in conjunction with these devices and currently clinicians are forced to make do with available force delivery materials. A new intrusion auxiliary, the Sydney Intrusion Spring (SIS), was designed to facilitate intrusion without frequent need for reactivation or tissue irritation.MethodsThe subjects consisted of 16 adolescent patients (12 females and 4 males) with an average age of 13.1 years (range 12.2 to 14.3 years). All patients were in the permanent dentition with an anterior open bite of ≥2 mm. Four self-drilling miniscrews were placed into the posterior maxillary buccal alveolar bone. The intrusion appliance consisted of a bonded acrylic appliance and the SIS, activated to produce an initial intrusive force of 500 g. Cone beam computed tomograms were taken after miniscrew placement and at the end of active intrusion. Rendered lateral cephalograms were produced and measurements were taken and compared.ResultsAll study objectives were achieved in 4.91 months (range 2.5 to 7.75 months). The mean molar intrusion was 2.9 ± 0.8 mm (P < .001), resulting in over bite increase of 3.0 ± 1.5 mm (P < .001). The intrusion led to a 2.6° ± 1.3° (P < .001) clockwise occlusal plane rotation and a 1.2° ± 1.3° (P < .01) counter-clockwise rotation of the mandible. Dental measurements showed a significant uprighting and elongation of the incisors. There was no significant extrusion of the lower molars.ConclusionThe SIS is an effective appliance for the intrusion of maxillary posterior teeth, in conjunction with miniscrews.

Camouflage Treatment of a Severe Open Bite Case

Skeletal open bite is a complex and multifactorial anomaly. There are many reasons for the occurrence of open bite, including skeletal abnormal growth pattern; dental, respiratory, neurologic, and habitual factors; and tongue posture and function. Anterior open bite is one of the most difficult problems to treat in orthodontics. Various treatment modalities for the correction of an anterior open bite have been proposed such as extrusion of anterior teeth using intermaxillary elastics, multiloop edgewise archwire technique developed by Kim, inhibition of molar eruption using bite blocks and high-pull headgear during growth, and extraction therapy. The most effective treatment option in adult patients is the repositioning of both the maxilla and mandible through a surgical correction. Although satisfactory results can be achieved with orthognathic surgery, the complexity, risks and costs of surgery are disadvantages of the surgical treatment. With the advent of skeletal anchorage, a number of studies were released to introduce the treatment of anterior open bite by intrusion of maxillary posterior teeth. This report presents the treatment and long-term stability of an adult case of a severe anterior open bite treated by means of extraction of the 4 first molars.

Occlusal plane change after intrusion of maxillary posterior teeth by microimplants to avoid maxillary surgery with skeletal Class III orthognathic surgery

To increase stability and mandibular setback movement, surgical maxillary impaction is normally performed with mandibular setback surgery in treating adult skeletal Class III patients. This article demonstrates the use of microimplants for anchorage to intrude molars and the resultant rotation of the maxillary occlusal plane clockwise to increase the surgical mandibular setback and reduce the posterior vertical dimension instead of maxillary surgical impaction. A 21-year-old man with mandibular prognathism was treated with mandibular setback surgery that included orthodontic treatment for decompensation. Microimplants placed into the palatal alveolar bone between the maxillary first and second molars were used to intrude the maxillary posterior teeth and change the occlusal plane clockwise. This produced 4 mm more of distal movement of the chin during mandibular setback surgery compared with the surgical prediction with no change in the occlusal plane. These results were similar to those of 2-jaw surgery with maxillary posterior impaction. The intrusion of the maxillary posterior teeth with microimplants might prevent the need for maxillary surgery in adult skeletal Class III patients.

Editor's Comment and Q&A: Long-term stability of anterior open-bite treatment by intrusion of maxillary posterior teeth

Introduction Anterior open bite results from the combined influences of skeletal, dental, functional, and habitual factors. The long-term stability of anterior open bite corrected with absolute anchorage has not been thoroughly investigated. The purpose of this study was to examine the long-term stability of anterior open-bite correction with intrusion of the maxillary posterior teeth. Methods Nine adults with anterior open bite were treated by intrusion of the maxillary posterior teeth. Lateral cephalographs were taken immediately before and after treatment, 1 year posttreatment, and 3 years posttreatment to evaluate the postintrusion stability of the maxillary posterior teeth. Results On average, the maxillary first molars were intruded by 2.39 mm (P <0.01) during treatment and erupted by 0.45 mm (P <0.05) at the 3-year follow-up, for a relapse rate of 22.88%. Eighty percent of the total relapse of the intruded maxillary first molars occurred during the first year of retention. Incisal overbite increased by a mean of 5.56 mm (P <0.001) during treatment and decreased by a mean of 1.20 mm (P <0.05) by the end of the 3-year follow-up period, for a relapse rate of 17.00%. Incisal overbite significantly relapsed during the first year of retention (P <0.05) but did not exhibit significant recurrence between the 1-year and 3-year follow-ups. Conclusions Most relapse occurred during the first year of retention. Thus, it is reasonable to conclude that the application of an appropriate retention method during this period clearly enhances the long-term stability of the treatment. Anterior open bite results from the combined influences of skeletal, dental, functional, and habitual factors. The long-term stability of anterior open bite corrected with absolute anchorage has not been thoroughly investigated. The purpose of this study was to examine the long-term stability of anterior open-bite correction with intrusion of the maxillary posterior teeth. Nine adults with anterior open bite were treated by intrusion of the maxillary posterior teeth. Lateral cephalographs were taken immediately before and after treatment, 1 year posttreatment, and 3 years posttreatment to evaluate the postintrusion stability of the maxillary posterior teeth. On average, the maxillary first molars were intruded by 2.39 mm (P <0.01) during treatment and erupted by 0.45 mm (P <0.05) at the 3-year follow-up, for a relapse rate of 22.88%. Eighty percent of the total relapse of the intruded maxillary first molars occurred during the first year of retention. Incisal overbite increased by a mean of 5.56 mm (P <0.001) during treatment and decreased by a mean of 1.20 mm (P <0.05) by the end of the 3-year follow-up period, for a relapse rate of 17.00%. Incisal overbite significantly relapsed during the first year of retention (P <0.05) but did not exhibit significant recurrence between the 1-year and 3-year follow-ups. Most relapse occurred during the first year of retention. Thus, it is reasonable to conclude that the application of an appropriate retention method during this period clearly enhances the long-term stability of the treatment.

Long-term stability of anterior open-bite treatment by intrusion of maxillary posterior teeth

Anterior open bite results from the combined influences of skeletal, dental, functional, and habitual factors. The long-term stability of anterior open bite corrected with absolute anchorage has not been thoroughly investigated. The purpose of this study was to examine the long-term stability of anterior open-bite correction with intrusion of the maxillary posterior teeth. Nine adults with anterior open bite were treated by intrusion of the maxillary posterior teeth. Lateral cephalographs were taken immediately before and after treatment, 1 year posttreatment, and 3 years posttreatment to evaluate the postintrusion stability of the maxillary posterior teeth. On average, the maxillary first molars were intruded by 2.39 mm (P<0.01) during treatment and erupted by 0.45 mm (P<0.05) at the 3-year follow-up, for a relapse rate of 22.88%. Eighty percent of the total relapse of the intruded maxillary first molars occurred during the first year of retention. Incisal overbite increased by a mean of 5.56 mm (P<0.001) during treatment and decreased by a mean of 1.20 mm (P<0.05) by the end of the 3-year follow-up period, for a relapse rate of 17.00%. Incisal overbite significantly relapsed during the first year of retention (P<0.05) but did not exhibit significant recurrence between the 1-year and 3-year follow-ups. Most relapse occurred during the first year of retention. Thus, it is reasonable to conclude that the application of an appropriate retention method during this period clearly enhances the long-term stability of the treatment.

Enhanced Effect of Combined Treatment With Corticotomy and Skeletal Anchorage in Open Bite Correction

To determine the effects of combined treatment with corticotomy and skeletal anchorage in open bite correction. Ten patients (6 females, 4 males) with ages ranging from 15 to 25 years were involved. All of the individuals received combined subapical corticotomy and skeletal anchorage procedure and intrusion forces of 200 to 300 g were applied on the attachments of each molar and both premolars during 12 to 15 weeks. Mean changes for the measurements for the sample group were evaluated with Wilcoxon signed ranks test. Significant intrusion of maxillary posterior teeth provided counterclockwise rotation of the mandible and open bite was successfully corrected. SNB angle increased and the ANB angle decreased (P< .05). Significant decreases were noted for vertical skeletal characteristics and overbite increased accordingly (P< .05). Our results indicated that the use of combined treatment with corticotomy and skeletal anchorage provided safe and noncompliance intrusion of posterior teeth in a short period and may be regarded as an alternative method for skeletal open bite correction in adults who reject orthognathic surgery.

Treatment and posttreatment changes following intrusion of maxillary posterior teeth with miniscrew implants for open bite correction

최근 절대적인 고정원의 등장으로 다른 부작용 없이 구치부 압하 치료를 가능하게 하였고, 비수술적으로 개방교 합의 심미적인 치료를 가능하게 하였다. 그러나, 이러한 치료법의 장기적인 안정성에 대한 연구는 많이 부족한 실정이다. 이에 본 연구에서는 miniscrew implant 를 이용하여 상악 구치를 압하시켜 치료한 성인 개방교합 환자 11명(남자 1명, 여자 10명) 을 대상으로 치료 전후, 그리고 유지기의 골격성, 치아 치조성 변화를 측모 두부 방사선사진을 이용하여 평가하였으며 계측치의 치료 전후 변화량간의 상관관계와 치료에 의한 변화량과 재발량과의 상관관계를 규명하여 상악구치의 압하를 통해서 개방교합을 치료할 때에 안정성을 평가하였다. 그 결과로 상악 구치는 2.22 mm 압하 (p $^{40}Ar/^{39}Ar$ 절대연대 자료는 제주도 동부 저지대 지역 대부분이 IV와 V 화산활동기 동안 분출된 200Ka 이내의 비교적 젊은 화산암류로 이루어져 있음을 지시한다. 이는 제주도 화산활동 시기 및 지형 형성에 대한 기존의 연구와는 상이한 결과이며, 화산암류의 K-Ar절대연대 자료를 바탕으로 한 기존의 제주도 화산활동 시기 구분이 재고되어야함을 확인하였다. 또한, 시추공에 근거한 화산 층서의 해석은 암석기재, 암석화학적 특징과 함께 절대연대 자료를 바탕으로 이루어져야 함을 강조한다. 방법의 개발이 필요하다. 따라서 퇴비원료로 이미 지정('02. 12. 31)된 제약오니 및 화장품 오니를 과량으로 토양에 시용한 후 유해 유기화합물, 미소동물, 미생물 및 생물학적(지렁이) 유해성 검정방법의 도입 가능성을 평가하기 거하여 고추를 재배한 포장에서 비료의 피해시험을 실시한 과 유해 유기화합물과 생물학적(지렁이) 유해성 검정방법은 앞으로 연구를 통해서 보완할 경우 상당히 활용 가능성이 있는 좋은 평가방법인 것으로 생각된다. 접촉 반응시간에 따른 탈착효율은 10분 이내에 전체 탈착량의 80%이상이 탈착 되었으며 1시간 이후에는 거의 변화가 없었다.장 내 B세포 및 T세포를 증가시켰으나, 마우스 흉선세포에 대해서는 증가를 보이지 않았다. ESMR은 마우스 섬유육종 세포에 대해 강한 세포독성 효과를 나타냈다. FSa II를 접종한 마우스에서 방사선 단독 보다 ESMR을 병용한 경우 방사선에 의한 세포손상이 약 50% 이상 증가되었으며, 두 군간의 차이는 통계학적 의미를 나타냈다(p 【Objective: This study investigated the skeletal and dentoalveolar changes after intrusion of maxillary posterior teeth using miniscrew implants during the treatment and posttreatment period. Method: The subjects consisted of 11 adults (1 male, 10 females) whose open bites were treated by posterior teeth intrusion with miniscrew. The lateral cephalometric x-rays of pre-treatment, post-treatment, and the retention period were evaluated. Results: The average intrusion of maxillary posterior teeth at the end of the treatment period was 2.22 mm (p】

P.299 Biomechanical efffects of orthodontic treatment by using anchorage device combined with corticotomy

To determine the effects of combined treatment with corticotomy and skeletal anchorage in open bite correction.Ten patients (6 females, 4 males) with ages ranging from 15 to 25 years were involved. All of the individuals received combined subapical corticotomy and skeletal anchorage procedure and intrusion forces of 200 to 300 g were applied on the attachments of each molar and both premolars during 12 to 15 weeks. Mean changes for the measurements for the sample group were evaluated with Wilcoxon signed ranks test.Significant intrusion of maxillary posterior teeth provided counterclockwise rotation of the mandible and open bite was successfully corrected. SNB angle increased and the ANB angle decreased (P < .05). Significant decreases were noted for vertical skeletal characteristics and overbite increased accordingly (P < .05).Our results indicated that the use of combined treatment with corticotomy and skeletal anchorage provided safe and noncompliance intrusion of posterior teeth in a short period and may be regarded as an alternative method for skeletal open bite correction in adults who reject orthognathic surgery.

The use of skeletal anchorage in open bite treatment: a cephalometric evaluation.

The aims of the present study were to assess the effectiveness of skeletal anchorage for intrusion of maxillary posterior teeth, to correct open bite malocclusion, and to evaluate the usage of titanium miniplates for orthodontic anchorage. Anterior open bite is one of the most difficult malocclusions to treat orthodontically. Currently, surgical impaction of the maxillary posterior segment is considered to be the most effective treatment option in adult patients. Various studies have reported the use of implants as anchorage units at different sites of midfacial bones for orthodontic tooth movement. The zygomatic buttress area could be a valuable anchorage site to achieve intrusion of maxillary posterior teeth. Ten patients, 17 to 23 years old and characterized with an anterior open bite and excessive maxillary posterior growth, were included in this preliminary study. Titanium miniplates were fixed bilaterally to the zygomatic buttress area, and a force was applied bilaterally with nine mm Ni-Ti coil springs between the vertical extension of the miniplate and the first molar buccal tube. The results showed that, with the help of skeletal anchorage, maxillary posterior teeth were intruded effectively. As compared with an osteotomy, this minimally invasive surgical procedure eased treatment and reduced treatment time and did not require headgear wear or anterior box elastics for anterior open bite correction. In conclusion, the zygomatic area was found to be a useful anchorage site for intrusion of the molars in a short period of time.