Maxillary Molar Intrusion Research Articles

Efficient usage of implant anchorage to treat overerupted maxillary first molar and mesially inclined mandibular molars

This case report demonstrates the efficient use of implant anchorage in a patient with mesially inclined mandibular molars and an overerupted maxillary molar. A 14-year-old girl had an overerupted maxillary right first molar, possibly because of severely inclined mandibular right molars. Two-step use of miniplate anchorage in the right zygomatic process was proposed. As the first step, the overerupted maxillary first molar was intruded with elastic chains from the miniplate for 10 months. Then the maxillary right molars were distalized by using the miniplate to correct the Class II molar relationship. In the mandible, the first molar was extruded with intermaxillary elastics applied from the miniplate to the molar for 7 months after the uprighting of the mandibular right second molar. The results suggest that the use of 2-step implant anchorage is efficient for intrusion and distalization of maxillary molars and extrusion and uprighting of mandibular inclined molars.

A prospective study of the short-term treatment effects of the acrylic-splint rapid maxillary expander combined with the lower Schwarz appliance.

This prospective clinical study evaluated the short-term treatment effects of acrylic-splint rapid maxillary expander in conjunction with lower Schwarz appliance (RME-Sz) therapy to the acrylic-splint rapid maxillary expansion alone (RME-only group). Pretreatment and posttreatment lateral cephalograms were analyzed for 25 RME patients and 19 RME-Sz patients. The average time between films ranged between nine and 12 months. Statistical comparisons of the treatment changes in the RME-only and RME-Sz groups were performed by means of independent sample t-tests (P < .05). The largest difference between the two groups was in lower anterior facial height (LAFH). The normally occurring increase in LAFH was not observed in the RME-only group during the treatment period, indicating that the acrylic-splint expander had a posterior "bite block effect" on the developing craniofacial complex. LAFH increased by 1.7 mm in the RME-Sz group, a value similar to that observed in untreated individuals. Slight forward displacement of the maxilla was observed when RME was used alone, and the sagittal position of the maxilla remained unchanged in the RME-Sz group. A significant amount of intrusion of the maxillary molars (-0.8 mm) was noted in the RME-only group, whereas the maxillary molars were prevented from erupting in the RME-Sz group. The lower dentition showed a significantly greater amount of extrusion in the RME-Sz group than in the RME-only group. Finally, the Sz appliance prevented the mesial movement of the lower molars during the treatment period.

Maxillary molar intrusion with fixed appliances and mini-implant anchorage studied in three dimensions.

The intrusion of an overerupted maxillary molar using traditional orthodontic treatment is a real challenge. The aim of this study was to investigate the envelope of intrusive movements of a maxillary molar in cases using mini-implants as anchorage with partial or full-mouth fixed edgewise appliances. The cusp tips of the pretreatment and postintrusion dental casts were recorded by a three-dimensional (3D) digitizer. The 3D data of the serial dental casts were analyzed to distinguish the direction and magnitude of individual tooth movement. The mean intrusive movement of the maxillary first molars was three to four mm, with a maximum of over eight mm. For the adjacent maxillary second molars and second premolars, the amount of intrusion was two mm and 1-2 mm, respectively. This study demonstrated that significant true intrusion of maxillary molars could be obtained in a well-controlled manner by using fixed appliances with titanium mini-implants as bony anchorage.

Closure of Severe Skeletal Anterior Open Bite With Zygomatic Anchorage

An open bite is commonly one of the main symptoms of an overall dentofacial deformity. Most anterior open-bite cases are characterized by excessive vertical development of the posterior maxilla. Intrusion of the overerupted molar teeth by traditional orthodontic methods is hardly possible; there is therefore no real alternative to a combined orthodontic and surgical approach. Skeletal anchorage has recently been proposed for the orthodontic movement of teeth. Titanium miniplates implanted in the zygomatic buttress area can serve as the absolute anchorage for maxillary molar intrusion. The aim of this study was to evaluate the use of skeletal anchorage for the closing of open-bite malocclusions. Seven patients with severe anterior open bites were selected, in all of whom the deformity was due to overeruption of the maxillary molars. Titanium miniplates were inserted bilaterally in the zygomatic buttress region and fixed with miniscrews. Elastic bands or coil springs were used to reduce excessive maxillary molar heights. In all cases, the anterior open bite improved significantly. The mean duration of active treatment was 6 months. No significant side effects were observed. Our results show that skeletal anterior open bites due to posterior maxillary dentoalveolar hyperplasia can be closed with intrusion of the upper molar teeth. This method is a safe, quick, and less expensive alternative to orthognathic surgery.

Three-dimensional dental model analysis of treatment outcomes for protrusive maxillary dentition: Comparison of headgear, miniscrew, and miniplate skeletal anchorage

The aim of this retrospective study on dental models was to compare the orthodontic outcomes of maxillary dentoalveolar protrusion treated with headgear, miniscrews, or miniplates for maximum anchorage. The 40 subjects were diagnosed as having either Angle Class II malocclusion or Class I bimaxillary dentoalveolar protrusion. All patients were treated to retract the maxillary dentoalveolar process by using the extraction space of the bilateral maxillary first premolars. They were divided into 3 groups according to the type of anchorage used. Group 1 (n = 16) received traditional anchorage preparation with a transpalatal arch and headgear, group 2 (n = 15) received miniscrews, and group 3 (n = 9) received miniplates for skeletal anchorage. To investigate the movement of the maxillary teeth during dentoalveolar retraction, we used a 3-dimensional (3D) digitizer to assess the positional changes of the maxillary teeth relative to the stable palatal rugose structures on the serial dental models. The 3D coordinates representing pretreatment and posttreatment maxillary dental casts were superimposed to determine the movement of individual teeth from the positional changes of 18 landmarks of the central incisor, canine, second premolar, and first molar. Three-dimensional analysis of the maxillary dental models in the buccopalatal, anteroposterior, and vertical directions showed significant differences in tooth movements between the headgear and the mini-implant (miniscrew or miniplate) groups. Both skeletal anchorage groups had greater incisor retraction (6.9 mm for the miniscrew, 7.3 mm for the miniplate) than did the headgear group (5.5 mm). Mesialization of occlusal centroid of the maxillary molar in the skeletal anchorage groups was less than that in the headgear group (1.3 mm for the miniscrew, 1.4 mm for the miniplate, 2.5 mm for the headgear). Tooth movements in the anteroposterior and buccopalatal directions did not reach a statistically significant difference between the miniscrew and miniplate groups, but the maxillary posterior teeth of the subjects receiving miniplates showed greater intrusion than those receiving miniscrews anchorage. This 3D analysis of serial dental models demonstrated that, compared with headgear, skeletal anchorage achieved better results in the treatment of maxillary dentoalveolar protrusion. Significant intrusion of the maxillary posterior teeth was noted in the miniplate group but not in the miniscrew and headgear groups. Greater retraction of the maxillary anterior teeth, less anchorage loss of the maxillary posterior teeth, and the possibility of maxillary molar intrusion all facilitated correction of the Class II malocclusion, especially for patients with a hyperdivergent face.

Intrusion of Overerupted Upper First Molar Using Two Orthodontic Miniscrews

Loss of the mandibular first molar often leads to the overeruption of the opposing maxillary first molar, resulting in occlusal interference, loss of periodontal bony support, and inadequate room to restore the mandibular edentulous space. Without orthodontic molar intrusion or segmental surgical impaction, restoring the posterior occlusion often entails the need for significant reduction of maxillary molar crown height, with the potential need for costly iatrogenic root canal therapy and restoration. The literature has cited successful maxillary molar intrusion with minor prosthodontic reduction using palatal orthodontic miniscrews and buccal zygomatic miniplates. In this report, the authors present successful maxillary molar intrusion with two orthodontic miniscrews in a patient with extreme dental anxiety and significant dental erosion due to gastric reflux. Using two orthodontic miniscrews for skeletal anchorage to intrude the maxillary molar simplified the orthodontic treatment by eliminating the need for extensive surgery, headgear, and intraoral multiunit anchorage and preserved indispensable tooth enamel. The clinical results showed significant intrusion through the maxillary sinus cortical floor while maintaining periodontal health, tooth vitality, and root length.

Avaliação cefalométrica das alterações dentoesqueléticas de jovens com má oclusão de Classe II dentária tratados com distalizadores Jones jig

OBJETIVO: esta pesquisa objetivou avaliar cefalometricamente as alterações dentoesqueléticas de jovens com Classe II dentária tratados com o distalizador Jones jig. METODOLOGIA: foram avaliados 30 pacientes, sendo 15 de cada gênero, com média de idades iniciais de 13,63 anos; brasileiros, naturais da cidade de Bauru/SP, caracterizados por má oclusão de Classe II, 1ª e 2ª divisões de Angle sem comprometimento esquelético. Os jovens foram tratados com aparelho Jones jig a fim de distalizar os molares superiores a uma relação molar de "super Classe I"; sendo que esse dispositivo permaneceu, em média, por 0,55 anos. Ao final da sobrecorreção, os molares distalizados receberam um botão de Nance e, como ancoragem extrabucal, o aparelho extrabucal (AEB) com tração média-alta, com o intuito de verticalizar e corrigir a angulação radicular dos molares distalizados. Foram realizadas telerradiografias em normal lateral inicial (T1) e pós-distalização (T2). As medidas cefalométricas foram submetidas ao teste t dependente de Student para avaliar as alterações de T1 para T2. RESULTADOS: com base nos resultados obtidos e a partir da metodologia empregada, observou-se alterações dentárias significativas, como a movimentação distal linear e angular, assim como a intrusão dos segundos e primeiros molares superiores no sentido vertical. Também se confirmou efeitos indesejáveis, como a perda de ancoragem refletida em mesialização, extrusão e angulação mesial dos segundos pré-molares, a protrusão dos incisivos superiores e o aumento do trespasse vertical e horizontal. Pode-se confirmar que certas movimentações dentárias promovem significativas alterações esqueléticas de estruturas localizadas à distância, ou seja, observou-se extrusão significativa dos segundos pré-molares superiores, o que resultou em rotação mandibular, aumento significativo da altura facial anteroinferior e protrusão do lábio inferior. CONCLUSÃO: pode-se concluir que o distalizador Jones jig promove, basicamente, alterações dentárias.

Maxillary molar intrusion with micro-implant anchorage (MIA)

Abstract Background: Intrusion of the maxillary molars is difficult to accomplish using traditional methods of anchorage. Aims: To describe methods of maxillary molar intrusion with the aid of micro-implants. Methods: Micro-implants provide stable intra-oral anchorage and enable the maxillary molars to be intruded without the usual side effects. Three adult patients are presented showing how micro-implants can be used to intrude the maxillary molars. In the first patient micro-implants were placed in the alveolar process between the second premolar and first molar, in the second patient micro-implants were placed in the palatal alveolar process between the first and second molars, and in the third patient a micro-implant was placed in the palate paramedially. A transpalatal bar was used to prevent bucco- or linguoversion of the molars during intrusion. Conclusions: The maxillary molars can be intruded with intra-oral anchorage derived from microscrew implants.

Minibone plates: The skeletal anchorage system

The skeletal anchorage system (SAS) is a recently developed orthodontic anchorage modality utilizing titanium miniplates and monocortical screws that are temporarily fixed in the maxilla and/or mandible for absolute orthodontic anchorage. The most appropriate application of the SAS is to enable the predictable intrusion and distalization of maxillary and mandibular molars. Therefore, the SAS offers a nonsurgical orthodontic treatment option for skeletal (surgical) malocclusions, as well as a nonextraction treatment approach for some malocclusions characterized by maxillary or mandibular protrusion, and/or anterior crowding.

Maxillary Molar Intrusion with Fixed Orthodontic Appliances and Bony Anchorage-A Preliminary Report with a 3-D Analysis

Overeruption of upper molars due to loss of antagonists may cause problems such as periodontal defects and occlusal interference. Molar intrusion requires anchorage support from intraoral multi-unit teeth, extraoral headgear wear or newly adopted miniscrew and miniplate as bony anchorages. The aim of this study was to investigate the amount of individual tooth movement within the same arch in cases of overerupted maxillary molars receiving partial or full-mouth fixed orthodontic treatment with miniscrews and miniplates used as anchorage. The surface topology of the cusp tips and incisal edges of the pretreatment and post-intrusion dental casts were recorded using a desktop mechanical 3D digitizer. The 3D data of the pretreatment and the post-intrusion dental casts were traced, processed, synthesized, and analyzed to distinguish the direction and magnitude & individual tooth movements. Results of this study demonstrated that the average intrusive movement of the upper first molars was 3 to 4mm with a maximum value of over 8mm. For the adjacent upper second molar and the upper first and second premolars, the amount of intrusion was around 2mm. A small difference between the buccal and palatal cusps was noted in the quantitative analysis of intrusive tooth movement. In conclusion, a significant amount of intrusion for overerupted maxillary molars can be obtained in a well-controlled manner using fixed appliances with mini-implants such as titanium miniscrews and miniplates serving as bony anchorage.

Initial intrusion of the molars in the treatment of anterior open bite malocclusions in growing patients.

The treatment of the hyperdivergent phenotype and/or anterior openbite is one of the common problems facing orthodontists. The purpose of this study is to present a new appliance (Molar Intruder) for molar intrusion and to determine its effects in the treatment of anterior openbite. The study group comprised 14 patients (eight girls and six boys), with a mean age of 10 years and 7 months. All presented anterior open bite malocclusions between the second premolars. The study was carried out on lateral head films taken before (T1) and after (T2) molar intrusion. Periapical radiographs, study models, and standard photographs of all the patients were also obtained before and after molar intrusion. The paired sample t-test was used to determine the differences between the parameters. The average treatment time with the Molar Intruder was five months. The mean intrusion of maxillary and mandibular molars was 1.86 mm and 1.04 mm, respectively. Maxillary incisors extruded 0.54 mm with a labial tipping of 1.46 degrees and overbite increased by 4.00 mm. The mandibular plane angle was decreased by 1.57 degrees, and the anterior face height was decreased by 1.86 mm on average. The mandible showed a counterclockwise rotation, the chin moved forward, and the posterior facial height/anterior facial height ratio was increased. Anterior openbites of the patients were significantly rehabilitated at the end of the intrusion period, simplifying further orthodontic treatment.

Effects of maxillary molar intrusion on the nasal floor and tooth root using the skeletal anchorage system in dogs.

The skeletal anchorage system (SAS) was developed to provide intraoral absolute anchorage for the intrusion or distalization of molars. The purpose of this study was to verify the effects of remarkable molar intrusion on the tooth root and the maxillary sinus floor. Six adult female beagles with fully erupted dentition were used. Titanium miniplates were implanted bilaterally above the maxillary second premolar root apices using pentobarbital anesthesia. The second premolars were intruded for four or seven months after three months of healing after implantation. Standardized dental radiographs were taken periodically to evaluate the amount of tooth movement and root resorption. After the experimental animals were fixed by perfusion at the end of each experimental period, the second premolars were dissected along with the surrounding alveolar bone. Undecalcified (60 microm thick) and decalcified (five microm thick) sections were prepared. The average extent of intrusion was 1.8 mm after four months and 4.2 mm after seven months. The root apices of the intruded molars penetrated into the nasal cavity. Remodeled bone around the intruded molar toots was rich in woven bone on the buccal side, whereas that on the palatal side was rich in lamellar bone. Nasal floor membrane and a thin layer of newly formed bone, which lifted intranasally, covered the intruded molar root. Root resorption partly reached into the dentine without the formation of reparative cementum, and little or no serious pathological changes were seen in the pulp of the intruded molars. SAS effectively intruded maxillary molars, but some moderate root resorption was observed.

Age effects on orthodontic treatment: Adolescents contrasted with adults

Skeletodental treatment changes in 30 adolescent girls and 26 women who had Class II, Division 1 malocclusions were contrasted cephalometrically, primarily with the McNamara analysis. The data show that adult treatment does not obligate the practitioner to longer treatment. In this study, both age groups were treated in 2.5 years on the average. Apical base corrections were achieved with equal facility in both groups by the posterior remodeling of point A, and this (in conjunction with unrestrained mandibular growth) is the major source of correction in the adolescents. In adults, in whom growth is trivial, an appreciable source of sagittal correction is the steepening of the occlusal plane. Several sequelae of Class II elastic force occurred as by-products of molar correction in the adults: increased mandibular molar eruption, increased maxillary molar intrusion, increased maxillary incisor eruption, increased mandibular incisor intrusion, and steepening of the occlusal plane.

Adaptability of the adult primate craniofacial complex to asymmetrical lateral forces

The adaptability of the adult craniofacial skeleton to altered functional relationships has been reported. An experimental quantification of these changes is lacking, however, and the possible underlying mechanisms of the alterations have not been explained. The purpose of this investigation was to evaluate the effect that lateral displacement of the mandible has on the dentoalveolar, craniofacial, and neuromuscular system in the adult rhesus monkey. Ten adult monkeys were studied; five served as controls, three were fitted with bilaterally inclined mandibular splints designed to deviate the mandible toward the left on closure, and two animals had flat splints to provide even occlusal contact. Pretreatment and posttreatment assessment of dentoalveolar and craniofacial change was made from mounted study casts, cephalometric head films, electromyograms and computed tomograms. Axial computed tomographic scans were used to evaluate potential changes in bone density at the lower part of the mandible, the condyle, the coronoid process, the neck of the condyle, and the zygomatic arch by means of a one-way analysis of variance. Changes in the measured variables were not observed in the control animals or in the animals with flat splints. Animals with inclined splints, however, demonstrated attrition and intrusion of maxillary molars and mild proclination of the maxillary incisors. Posttreatment computed tomographic scans in these animals showed significantly increased bone density in the right coronoid process (p less than 0.05) and bilaterally at the necks of the condyles (p less than 0.005). Resting electromyographic activity remained low and was not significantly different among the three groups.(ABSTRACT TRUNCATED AT 250 WORDS)

A cephalometric evaluation of anterior openbite correction with the magnetic active vertical corrector.

The purpose of this study was to evaluate treatment effects of the magnetic active vertical corrector appliance (AVC) when used to treat anterior openbites in a sample of growing patients. Twenty-five patients with a mean age of 10 years 8 months underwent AVC treatment for an average of almost 8 months. They had an average of 3 mm of anterior openbite closure during the treatment period, primarily due to maxillary and mandibular molar intrusion. Additional contributions to correction of the openbite were related to maxillary incisor eruption and lingual tipping combined with mandibular incisor lingual movement. A small amount of mandibular rotation with closure of the bite and decrease in anterior force height was observed. Anteroposterior skeletal change attributed to the AVC therapy was minimal.