Incisor Retraction Research Articles

Midpalatal miniscrews and high-pull headgear for anteroposterior and vertical anchorage control: Cephalometric comparisons of treatment changes

Our aim was to evaluate which anchorage system is better suited for both anteroposterior and vertical anchorage control of maxillary posterior teeth. Fifty-one subjects requiring maximum anchorage were divided into 2 groups according to maxillary posterior anchorage reinforcement: high-pull headgear, conventional transpalatal arch, and interarch elastics (n= 28); or modified transpalatal arch supported by 2 midpalatal miniscrews (n= 23). Bilateral maxillary first premolars were extracted in all patients. Pretreatment and posttreatment lateral cephalometric radiographs were superimposed to compare skeletal and dental changes between the groups. (1) The miniscrew group had less mesial movement of the maxillary first molars (0.85 vs 3.63 mm) and greater maxillary incisor retraction (6.87 vs 4.50 mm) than did the headgear group with the same treatment duration. (2) The maxillary molars were significantly intruded in the miniscrew group (1.30 mm), whereas they were extruded in the headgear group (0.71 mm). In the miniscrew group, intrusion of the maxillary molars resulted in a statistically significant decrease in the mandibular plane angle (0.80°). Patients using high-pull headgear showed no significant decrease in these measurements. In both the anteroposterior and vertical directions, a modified transpalatal arch supported by 2 midpalatal miniscrews provided more stable anchorage.

Treatment of Class II Division 1 Malocclusion using Cervical Headgear

Class II division 1 malocclusions have many variation and treatment options. Choosing the right treatment begins with a correct diagnosis. The aim of this article is to describe treatment of Class II division 1 malocclusion in a growing patient using combined cervical headgear and non-extraction fixed orthodontic therapy. Class I molar and canine relationship was achieved with normal overbite and overjet. There is improvement in jaw relationship and facial profile. This correction was achieved by downward displacement and inhibition of the forward growth of maxilla with favorable growth of mandible, upper molar distalization and retraction of upper incisors from cervical headgear use. There was neither downward rotation of the mandible nor maxillary first molar extrusion. Treatment time, favorable mandibular growth pattern and patient compliance proved to be determining factors in the success of this treatment. DOI: 10.14693/jdi.v16i3.106

Nonsurgical correction of a Class III malocclusion in an adult by miniscrew-assisted mandibular dentition distalization

This article reports the successful use of miniscrews in the mandible to treat a 20-year-old Mongolian woman with a chief complaint of anterior crossbite. The patient had a skeletal Class III malocclusion with a mildly protrusive mandible, an anterior crossbite, and a deviated midline. In light of the advantages for reconstruction of the occlusal plane and distal en-masse movement of the mandibular arch, we used a multiloop edgewise archwire in the initial stage. However, the maxillary incisors were in excessive labioversion accompanied by little retraction of the mandibular incisors; these results were obviously not satisfying after 4 months of multiloop edgewise archwire treatment. Two miniscrews were subsequently implanted vertically in the external oblique ridge areas of the bilateral mandibular ramus as skeletal anchorage for en-masse distalization of the mandibular dentition. During treatment, the mandibular anterior teeth were retracted about 4.0 mm without negative lingual inclinations. The movement of the mandibular first molar was almost bodily translation. The maxillary incisors maintained good inclinations by rotating their brackets 180° along with the outstanding performance of the beta-titanium wire. The patient received a harmonious facial balance, an attractive smile, and ideal occlusal relationships. The outcome was stable after 1 year of retention. Our results suggest that the application of miniscrews in the posterior area of the mandible is an effective approach for Class III camouflage treatment. This technique requires minimal compliance and is particularly useful for correcting Class III patients with mild mandibular protrusion and minor crowding.

Characteristics of dentoskeletal morphology and treatment changes in 2-maxillary premolar extraction: A comparison with 4-premolar extraction

BackgroundThe present study aimed to clarify the characteristics of dentoskeletal morphology and treatment changes after 2-maxillary premolar extractions to treat Class II malocclusion, by comparing pre- and post-treatment lateral cephalograms and dental casts from cases with 4-premolar extractions. MethodsSubjects comprised patients who had undergone orthodontic treatment for Class II molar relationship using either maxillary first premolar extraction (U2 group, n = 27) or maxillary and mandibular first premolar extraction (UL4 group, n = 27). Pretreatment (T1) and post-treatment (T2) lateral cephalograms and dental casts were examined. Groups were compared for differences at T1 and T2, and in T2–T1 change using unpaired t tests. Among the analysis items showing significant differences at T1, those that could discriminate between groups U2 and UL4 at T1 were extracted by stepwise logistic regression analysis. ResultsDentoskeletal morphology in the U2 group exhibited a severe Class II molar relationship, little need for maxillary incisor retraction, and a morphology in which bite opening was severe. Treatment changes in the U2 group showed that extraction spaces were used for mesial movement of maxillary molars in many cases, that bite-opening resulted from mandibular clockwise rotation, and that contraction of the upper arch and expansion of the lower arch occurred in anteroposterior and lateral directions. Severity of Class II molar relationship, anteroposterior position of mandibular incisors, and lower arch depth were selected as criteria for distinguishing pretreatment between groups U2 and UL4. ConclusionCases with 2-maxillary premolar extraction showed a characteristic dentoskeletal morphology compared to cases with 4-premolar extraction.

Reconstruction of a collapsed dental arch in a patient with severe periodontitis

This case report describes the significance of orthodontic treatment in reconstruction of a collapsed dental arch and a malocclusion associated with severe periodontitis. A Japanese man (age, 40 years 7 months) had an anterior crossbite, a collapsed occlusion, and severe periodontitis. Orthodontic treatment included the following steps: (1) correction of the anterior crossbite, labial movement of the maxillary incisors, and intrusion and retraction of the mandibular incisors; (2) correction of the posterior crossbite on the left side, buccal movement of the maxillary left canine and first premolars, and intrusion and retraction of the mandibular first premolar into the space of the mandibular left canine; (3) correction of the crowding of the mandibular right buccal segment and alignment of the teeth after extraction of the mandibular right first molar with a periapical lesion; and (4) improvement of the occlusion, with reconstruction of an acceptable occlusion. When combined with restorative and prosthodontic treatment, a fairly good occlusion was obtained. Reevaluation of the treatment after 11 years showed that the occlusion and periodontal condition were maintained well without deepening of the pockets and further bone loss. Orthodontic treatment with a systematic approach helped to recover the occlusion and prevented the recurrence of periodontitis by acquiring a good oral environment and motivating the patient to maintain oral health.

Maxillary incisor retraction: evaluation of different mechanisms

To mechanically evaluate different systems used for incisors retraction. Three different methods for incisors retraction using 0.019 x 0.025-in stainless steel wire were evaluated. The samples were divided into three groups: Group A (retraction arch with 7-mm high vertical hooks); Group G3 (elastic chain attached to the mini-implant and to the 3-mm stainless steel hook welded to the retraction arch); Group G6 (elastic chain attached to the mini-implant and to the 6-mm stainless steel hook welded to the retraction arch). A dental mannequin was used for evaluation in order to simulate the desired movements when the device was exposed to a heat source. The analysis of variance (ANOVA) and the Tukey test were used (p < 0.05). The results demonstrated that Groups G3 and G6 exhibited less extrusion and less incisor inclination during the retraction phase (p < 0.05). With regard to incisor extrusion, statistically significant differences were observed between Groups A and G3, and between Groups A and G6 (p < 0.05). Regarding incisor inclination, statistically significant differences were observed between the three evaluated systems (p < 0.05). Arches with 6-mm vertical hooks allow the force to be applied on the center of resistance of the incisors, thus improving mechanical control, when compared with the other two systems.

The use of miniscrew as orthodontic anchorage in correction of maxillary protrusion with occlusal cant, spaced arch, and midline deviation without surgery

This report describes the use of the miniscrew as orthodontic anchorage in maxillary protrusion with a spaced arch and midline deviation in a 16-year-old female patient. In cases with midline deviation, a cant in the maxillary occlusal plane is often observed. Thus, the authors used the miniscrew to control the vertical dimension, thereby flattening the maxillary occlusal plane, and to close and retract the incisors to improve her convex profile. Effective incisor intrusion to correct the deep overbite was also observed. In addition, functional evaluation by a 6-degrees-of-freedom jaw movement recording system was performed. Significant improvement in the jaw movement was observed during maximum opening and lateral excursion during the retention phase. The authors suggest that miniscrews are effective in correcting midline deviation due to maxillary occlusal cant and intrusion and retraction of incisors, and may result in favorable functional movement of the jaw.

Changes in alveolar bone thickness due to retraction of anterior teeth during orthodontic treatment: A cephalometric and computed tomography comparative study

Evaluate the changes in alveolar bone as a result of maxillary and mandibular incisor retraction in patients with bimaxillary protrusion by means of using lateral cephalograms and computed tomography (CT) scans and to investigate any occurrence of bony defects like dehiscence and fenestration. Ten patients (age 15 ± 3 years) with bimaxillary protrusion treated by extraction of four first premolars were investigated by lateral cephalograms and CT scans during pre-treatment (T1) and after 3 months of completion of incisor retraction (T2). The labial and lingual cortex of all the incisors were assessed on the CT scan with measurements taken at site adjacent to widest point of the labiolingual root in three slices separated by 3 mm at crest level (S1), mid root level (S2), and apical level (S3). In the mandibular arch, after lingual movement of the incisors, the bone labial to the anterior teeth decreased in thickness at the coronal level of the left lateral and left central incisors. Left lateral incisor showed significant changes in all the three levels. In the maxilla the change in the labial bone thickness was not statistically significant. Lingual bone of all the incisors showed significant changes in S1 level and S3 levels. Few patients demonstrated bone dehiscence that was not visible macroscopically or cephalometrically. When incisors are retracted, the risk of adverse effect is present. This must be carefully monitored to avoid negative iatrogenic effects. This study needs follow up after 6 months or 1 year after completion of the orthodontic treatment to assess the long-term consequences.

Changes of the upper lip in orthodontic and orthopedic treatment of angle′s class II malocclusion

This study aimed to evaluate the changes in upper lips due to incisors retraction in Class II Division 1 patients treated with mandibular protraction, fixed appliances, and without extraction. The sample consisted of 64 pre- and post-treatment lateral cephalometric X-rays of 32 patients with 9-12 years old (16 men and 16 women), who presented ANB > 4 o , overjet ≥ 4 mm, treated with Balter's Bionator and fixed appliances. The average period between initial and final radiographies was 5 years (maximum of 5.5 years and minimum of 4.5 years). A Student's t-test (P < 0.01) evaluated the statistical significance of differences between the mean values obtained for pre- and post-treatment in each variable, for males and females. Linear regression analysis for hard-tissue variables in relation to soft-tissue variables were also made for correlation. The male group presented cervical point with r = 0.40 and incisal point with r = 0.42. Female subjects showed incisor cervical point with r = 0.86 and incisal point r = 0.74. The average Ls retraction was 0.55 mm in 2.43 mm of incisal point movement and 0.34 mm of cervical point. The nasolabial angle showed increase average of 2° for men and 3.9° for women. There is a difference between genders regarding the lip-incisor relation at this age. Males presented thickening of soft tissue and week correlation between the movement of the incisor and soft tissue both cervical and incisal point. In females' subjects, a strong correlation between the retraction movement and soft tissue, both cervical and incisal point.

A comparison of second premolar extraction and mini-implant total arch distalization with interproximal stripping

The effect of total arch distalization using orthodontic mini-implants (OMIs) combined with interproximal stripping (IPS) and second premolar extraction was investigated in Class I malocclusion patients. A total of 66 consecutively treated Class I malocclusion (Class I molar relationship; 0 mm < overbite and overjet < 4.5 mm) patients ranging in age from 17 to 44 years who received single-phase treatment were included in this study. Pre- and posttreatment lateral cephalograms and dental casts were measured and compared statistically. In the distalization with IPS group, 3.6 mm and 3.8 mm of crowding in the upper and lower arches, respectively, were resolved, and 3.8 mm and 3.2 mm of upper and lower incisor retraction, respectively, were achieved simultaneously by the treatment. As a result of the second premolar extraction treatment, 3.9 mm and 3.6 mm of crowding in the upper and lower arches, respectively, were resolved, and 3.3 mm and 3.2 mm of incisor retraction, respectively, were achieved during treatment. There was no statistically significant difference in the amount of crowding and incisor retraction between the two groups. Total arch distalization using an OMI with IPS did not yield a significantly different treatment result compared to second premolar extraction treatment.

Onychophagia and postorthodontic isolated gingival recession: Diagnosis and treatment

This clinical report describes the diagnosis and the management of isolated-type recession defects of complex etiology in 2 healthy postorthodontic patients. The lesions were confined to 1 mandibular incisor and were associated with an abnormal buccolingual inclination of the affected tooth despite a lingual retainer made with a round stainless steel twisted wire. After careful questioning, it was determined that the recession defects were indirect effects of habitual onychophagia. The concomitant fingernail-biting habit and the lingual bonded retainer led to the indirect development of bone dehiscence and, consequently, gingival recession.

Orthodontic management of a patient with missing upper posterior teeth, severe curve of Spee and periodontal problems

This article describes the complex dental treatment of an adult patient with missing upper posterior teeth, malocclusion with a severe curve of Spee and generalized moderate chronic periodontitis. A skeletal Class II due to a retruded mandible with high overjet and overbite and labial inclination of the maxillary incisors were also present. Based on the loss of supporting periodontal tissue, missing upper posterior teeth and extrusion of the antagonist teeth, with consequent loss of space for rehabilitation, the orthodontic treatment consisted of a mini-screw anchorage on the posterior maxilla. A multiloop edgewise arch wire was applied in the lower arch in order to correct the severity of the curve of Spee, intruding posterior teeth and incisors. When the occlusal plane was established and a normal interocclusal space was obtained at the posterior teeth a prosthodontic treatment with implants was done to replace the missing teeth. In spite of the high skeletal Class II at the end of the treatment, the overall treatment improved periodontal attachments and a Class I dental relationship was achieved with a slight mandibular anterior repositioning. Furthermore, improved aesthetics of the patient was obtained by upper incisor retraction without increasing vertical dimensions.

Factors related to alveolar bone thickness during upper incisor retraction

To investigate the factors related to changes in alveolar bone thickness during upper incisor retraction. The subjects consisted of 23 ongoing orthodontic patients (mean age 20.4 ± 2.7 years) whose upper incisors were bound for retraction. Changes in alveolar bone thickness in the retracted area were assessed using preretraction (T0) and postretraction (T1) cone-beam computed tomography images. Labial bone thickness (LBT), palatal bone thickness (PBT), and total bone thickness (TBT) were assessed at the crestal, midroot, and apical levels of the retracted incisors. Paired t-tests were used to compare T0 and T1 bone thickness measurements. Spearman's rank correlation analysis was performed to determine the relationship of changes in alveolar bone thickness with the rate of tooth movement, change in inclination, initial alveolar bone thickness, and the extent of intrusion. As the upper incisors were retracted, the LBT at the crestal level and TBT at the apical level significantly increased (P < .005). Changes in alveolar bone thickness were significantly associated with the rate of tooth movement, change in inclination, and extent of intrusion (P < .05) but not initial alveolar bone thickness (P > .05). Rate of tooth movement, change in inclination, and extent of intrusion are significant factors that may influence alveolar bone thickness during upper incisor retraction. These factors must be carefully monitored to avoid the undesirable thickening of alveolar bone.

Conservative treatment of a Class I malocclusion with 12 mm overjet, overbite and severe mandibular crowding

INTRODUCTION: A female patient aged 12 years and 2 months had molars and canines in Class II relationship, severe overjet (12 mm), deep overbite (100%), excessive retroclination and extrusion of the lower incisors, upper incisor proclination, with mild midline diastema. Both dental arches appeared constricted and a lower arch discrepancy of less than -6.5 mm. Facially, she had a significant upper incisors display at rest, interposition and eversion of the lower lip, acute nasolabial angle and convex profile. OBJECTIVE: To report a clinical case consisting of Angle Class I malocclusion with deep overbite and overjet in addition to severe crowding treated with a conservative approach. METHODS: Treatment consisted of slight retraction of the upper incisors and intrusion and protrusion of the lower incisors until all crowding was eliminated. RESULTS: Adequate overbite and overjet were achieved while maintaining the Angle Class I canine and molar relationships and coincident midlines. The facial features were improved, with the emergence of a slightly convex profile and lip competence, achieved through a slight retraction of the upper lip and protrusion of the lower lip, while improving the nasolabial and mentolabial sulcus. CONCLUSIONS: This conservative approach with no extractions proved effective and resulted in a significant improvement of the occlusal relationship as well as in the patient's dental and facial aesthetics.

Apical root resorption in maxillary incisors when employing micro-implant and J-hook headgear anchorage: A 4-month radiographic study

This study evaluated, over a 4-month study period, the amount of apical root resorption occurring in maxillary central incisors following their retraction when employing either micro-implant or J-hook headgear anchorage. The prospective randomised clinical trial was conducted in Orthodontic Clinic, College of Stomatology, China from 2008-2009. Subjects are patients requiring fixed appliances on waiting list (n=20). In female Han Chinese patients aged from 16-26 years, standardized periapical radiographs from 10 randomly assigned patients with maxillary protrusions comprising the micro-implant group, and from 10 similar patients comprising the J-hook headgear group, were assessed for maxillary central incisor apical root resorption. Measurements before and after orthodontic therapy were also obtained from lateral cephalometric radiographs to calculate incisor horizontal retraction and vertical intrusion distances. Estimated retraction force vectors were calculated in horizontal and vertical directions for both treatment groups. Data analysis employed t-tests and the Pearson correlation test, with α=0.05 for statistical significance. The results showed that when compared with the J-hook group, significantly more apical root resorption shortening of the maxillary central incisors was observed in the micro-implant group (1.27 mm difference, 95% CI=0.70-1.84, P<0.001), which was associated with a significantly larger retraction distance (P=0.004) and a smaller vertical force component (P<0.0001). We are led to conclude that continuous activation of the nickel-titanium coil springs used in the micro-implant group resulted in significantly more apical root resorption shortening and maxillary central incisor retraction than when intermittent J-hook retraction was employed. The employment of continuous duration orthodontic forces presents a risk for increased apical root resorption that requires careful radiographic monitoring.

Tooth movement using palatal implant supported anchorage compared to conventional dental anchorage

Tooth stability is one of the most changing parameters in age. The aim of the present study has been to clarify the therapeutic benefit of the osseointegrated palatal implant (PI) supported anchorage in adolescents compared with conventional dental anchorage (DA) in extraction cases requiring 'maximum anchorage' in growing patients following the post pubertal growth spurt. Thirty patients (14.22±1.37 years) selected with homogeneous facial skeletal characteristics were divided in two groups. In the PI group, Orthosystem(®) implants were placed into the palate for anchorage and the transpalatal arch (TPA) was fixed to the implant and to the molar bands. In the DA group maximal anchorage was provided by a TPA and a utility arch. Super-elastic spring was used for canine- and contraction arch for incisor retraction. An insignificant difference was observed between the groups as to the duration of the canine retraction. In the PI group, the duration of the front retraction and the total treatment time was shorter compared to the DA group (P<0.05). No significant difference in molar mesial movement was found during canine retraction, but during front retraction, there was significantly less mesial molar movement in the PI group compared to the DA group (P<0.05). The use of palatal implant-based anchorage does not offer a shorter canine retraction period, but resulted in a significant shortening of the front-retraction phase and a total treatment time shortened by 5 months on average. The tooth stability in adolescent patients is adequate for tooth movements using both methods.

Residents' journal review

Residents' journal review

A prospective comparative study between differential moments and miniscrews in anchorage control

The purpose of this study was to measure the efficacy of anchorage control between differential moments mechanics and temporary anchorage devices in a clinical trial. Forty-six patients requiring extraction of maxillary first premolars were allocated into 2 treatment groups. The differential moments group (G1) received a nickel titanium (NiTi) intrusion arch and a 150g NiTi closing coil spring for separate canine retraction, followed by a continuous mushroom loop archwire for the retraction of the incisors. The TAD group (G2) received one miniscrew placed between maxillary second premolars and first molars with a 150 g NiTi closing coil spring connecting the miniscrew to a hook placed in the archwire between the lateral incisor and canine. Lateral cephalograms were taken before (T1) and after incisor retraction (T2). The ratio of molar protraction to incisor retraction was calculated and intragroup and intergroup changes in upper lip, maxillary incisor and molar position were analyzed by paired and independent t-tests. Twenty-eight patients were analyzed after 18 patients did not receive the intervention, were lost to follow-up, or discontinued treatment. The ratio of molar protraction to incisor retraction in G1 was 0.44 and in G2 was -0.11, which was significantly different. There was a statistically significant change in upper lip from T1 to T2 but no difference between the two groups. Moreover, there was a significant distal molar tipping and lingual incisor tipping in G2. There is a significant difference in the amount of anchorage control using differential moments mechanics compared to TADs. Although statistically significant retraction of upper lip was observed in both groups, there was no significant difference between the two groups.

Assessment of facial profile changes in Class I biprotrusion adolescent subjects submitted to orthodontic treatment with extractions of four premolars

OBJECTIVE: To evaluate cephalometric changes in tooth and profile position in young adolescent individuals with Class I biprotrusion submitted to orthodontic treatment with extractions of four first premolars. METHODS: Pre and posttreatment lateral cephalometric radiographs from 20 patients with Class I biprotrusion malocclusion were used to evaluate the following measurements: nasolabial angle, distance from lips to E line, distance from lips, incisors, tip of the nose and soft tissue pogonion to Sy line. RESULTS: All measurements showed significant changes after treatment (p<0.05), except the distance from lips and soft tissue pogonion to Sy line. There was a positive correlation between the retraction of incisors and the change of upper and lower lips (0.803/0.925; p<0.001). CONCLUSION: The profile retrusion observed occurred more due to nose growth than to lips retraction. The response from soft tissues to incisors retraction showed a great variability.

Esthetic orthodontic treatment with a double J retractor and temporary anchorage devices

This clinical article reports an esthetic treatment option for managing a Class II malocclusion in an adult. The patient, a woman aged 24 years 2 months, had crowding and a convex profile. She was treated with maxillary first premolar extractions, a double J retractor, and temporary skeletal anchorage devices in the maxillary arch. Posttreatment records after 2 years showed excellent results with good occlusion and long-term stability.