Extraction of Maxillary Central Incisors with Short Roots for Orthodontic Treatment of Maxillary Protrusion and Open Bite.

This case report describes the unusual choice of extraction of maxillary incisors with short roots as part of an orthodontic treatment plan. The patient was a 20-year-old woman referred to our department in whom the diagnosis was maxillary protrusion and open bite. Both of the maxillary central incisors had short roots. Two treatment options were considered. The first involved extraction of the 4 first premolars with the aim of improving dentoalveolar protrusion and crowding. If preservation of the central incisors subsequently became difficult due to root resorption, prosthetic options were to be considered. The second treatment option involved extraction of the maxillary central incisors with short roots and the mandibular first premolars. The second treatment option was selected as survival of the central incisors following orthodontic movement was uncertain and the patient also wanted to minimize the risk of future extractions and the use of prosthetics. Active treatment was performed over a span of 31 months, and circumferential type retainers were used on both arches for retention. For such treatment to be successful, careful diagnosis and orthodontic treatment planning must be taken to ensure the anterior dental esthetics are properly restored.

Esthetic Improvement through Orthodontic Treatment Involving Extraction: Use of Orthodontic Anchor Screws.

Here, we report two cases of dental bimaxillary protrusion in which orthodontic anchor screws were used to improve the esthetics of the mouth and lips and facilitate complete closure of the mouth. Case 1 was a woman with dental maxillary protrusion and constriction of the dental arches, with the main complaint of protrusion of the lips and mandibular crowding. The maxillary and mandibular dental arches were first widened and traction applied to the maxilla via orthodontic anchor screws. The maxillary incisors were retracted 10 mm and the mandibular incisors 3 mm, resulting in upper lip retraction of 3 mm and bottom lip retraction of 5 mm with respect to the E-line. The nasolabial angle increased to 20°, and the inter-vermilion angle, which indicates the thickness of the vermillion, decreased to 20°, improving esthetics by reducing the thickness of the lips. Case 2 was a woman with bimaxillary dental protrusion, with the chief complaint of protruding lips and a gummy smile. Orthodontic anchor screws were used to achieve posterior traction and intrusion in the maxillary incisor region to improve the gummy smile. The maxillary incisors were retracted 9 mm and the mandibular incisors 8 mm. In the soft tissues, this yielded upper lip retraction of 3 mm and bottom lip retraction of 4 mm with respect to the E-line. The nasolabial angle increased to 10° and the inter-vermilion angle decreased to 30°, improving esthetics by reducing the thickness of the lips. The gummy smile was also improved, with 4 mm intrusion of the maxillary incisors. Increased ease in closing of the mouth was also a major factor in patient satisfaction with the results of orthodontic treatment.

Finite Element Analysis of Stress in Maxillary Dentition during En-masse Retraction with Implant Anchorage.

The goal of this study was to investigate how the height of the archwire hook and implant anchor affect tooth movement, stress in the teeth and alveolar bone, and the center of resistance during retraction of the entire maxillary dentition using a multibracket system. Computed tomography was used to scan a dried adult human skull with normal occlusion. Three-dimensional models of the maxillary bone, teeth, brackets, archwire, hook, and implant anchor were created and used for finite element analysis. The heights of the hook and the implant anchor were set at 0, 5, or 10 mm from the archwire. Orthodontic force of 4.9 N was systematically applied between the hook and the implant anchor and differential stress distributions and tooth movements observed for each traction condition. With horizontal traction, the archwire showed deformation in the superior direction anterior to the hook and in the inferior direction posterior to the hook. Differences in traction height and direction resulted in different degrees of deformation, with biphasic movement clearly evident both in front of and behind the hook. With horizontal traction of the hook at a height of 0 mm, all the teeth moved distally, but not with any other type of traction. At a height of 5 mm or 10 mm, deformation showed an increase. The central incisor showed extrusion under all traction conditions, with the amount showing a reduction as the height of horizontal or posterosuperior traction increased. The center of resistance was located at the root of the 6 anterior teeth and entire maxillary dentition. The present results suggest that it is necessary to consider deformation of the wire and the center of resistance during en-masse retraction with implant anchorage.

Case of Severe Maxillary Protrusion Accompanied by Crowding and Scissor Bite.

This case involved a 30-year-old woman who visited our hospital with the main complaint of protrusion of the maxillary incisors and upper and lower lips. She had difficulty closing her lips, and a chin button was observed when the lips were closed. The skeletal pattern showed maxillary protrusion and mandibular retrusion, and the mandible showed severe high angle. Labial inclination of both the maxillary and mandibular incisors was found, as well as crowding. In addition, the maxillary left second molar showed buccal displacement, and scissor bite was evident in the left second molar region. The bilateral molar relationship was cusp-to-cusp class II malocclusion. Angle class II maxillary protrusion accompanied by crowding and left second molar scissor bite was diagnosed. Surgical orthodontic treatment was judged as the best approach to treat the jaw deformities. However, in line with the wishes of the patient, treatment was undertaken using implant anchors instead. Straight-wire brackets with a 0.022-inch slot were fitted. A lingual arch was placed in the mandible and plate-type implant anchors in the first molar region of the maxilla. Almost no change was observed in skeletal pattern as no surgery was performed. The maxillary incisors moved back 10 mm, however, and the mandibular incisors showed an improvement of 4 mm from L1 to APo. The upper and lower lips consequently moved back 7 mm with respect to the E-line. Active treatment required 3 years and 6 months. Esthetic and functional improvements were achieved.

A Newly Proposed Method to Predict Optimum Occlusal Vertical Dimension.

PURPOSE: Establishing the optimum occlusal vertical dimension (OVD) in prosthetic treatment is an important clinical procedure. No methods are considered to be scientifically accurate in determining the reduced OVD in patients with missing posterior teeth. The purpose of this study was to derive a new formula to predict the lower facial height (LFH) using cephalometric analysis. MATERIALS AND METHODS: Fifty-eight lateral cephalometric radiographs of Japanese clinical residents (mean age, 28.6 years) with complete natural dentition were used for this study. Conventional skeletal landmarks were traced. Not only the LFH, but six angular parameters and four linear parameters, which did not vary with reduced OVD, were selected. Multiple linear regression analysis with a stepwise forward approach was used to develop a prediction formula for the LFH using other measured parameters as independent variables. RESULTS: The LFH was significantly correlated with Gonial angle, SNA, N-S, Go-Me, Nasal floor to FH, Nasal floor to SN, and FH to SN. By stepwise multiple linear regression analysis, the following formula was obtained: LFH (degree) = 65.38 + 0.30* (Gonial angle; degree) - 0.49* (SNA; degree) - 0.41* (N-S; mm) + 0.21* (Go-Me; mm) - 15.45* (Nasal floor to FH; degree) + 15.22* (Nasal floor to SN; degree) - 15.40* (FH to SN; degree). CONCLUSIONS: Within the limitations of this study for one racial group, our prediction formula is valid in every LFH range (37 to 59°), and it may also be applicable to patients in whom the LFH deviated greatly from the average.

Orthodontic treatment in combination with Le Fort II bone distraction in patient with Apert syndrome.

We report a case of an 11-year-old girl presenting with Apert syndrome characterized by midface concavity, protrusion of the eyeballs, and ocular hypertelorism. She had class III anterior crossbite, narrow upper and lower arches, and marked crowding. Based on cephalometric analysis, anterior crossbite associated with marked midfacial hypoplasia was diagnosed. Orthodontic treatment in combination with Le Fort II maxillary distraction was scheduled. The dentition was laterally extended using a Rapid palatal expander in the upper jaw and a Bihelix in the lower jaw. Multi-bracket appliances were simultaneously applied for leveling. Next, Le Fort II maxillary osteotomy was performed to distract the midface bone 16 mm anteroinferiorly using a rigid external distraction system. Orthodontic treatment was completed at 3.8 years after initiation. Bone distraction moved the upper jaw anteriorly downward, and the lower jaw subsequently rotated posteriorly downward, leading to a marked improvement in facial appearance and occlusion. Elongation of the dorsum of the nose, in particular, allowed esthetic improvement of the saddle nose. These improvements remain stable at 2 years after orthodontic treatment.

Dental implant treatment after improvement of oral environment by orthodontic therapy.

A 57-year-old man presented with mesial inclination of the lower right first molar caused by untreated loss of the second premolar. The occlusal relationship was restored by dental implant treatment following improvement of the intraoral environment by orthodontic therapy. At his initial visit, the interdental spacing in the molar-premolar region was inadequate, as the first molar had mesially inclined into the extraction space of the second premolar. The patient had also lost the second molar and complained of masticatory problems on the right side. It was considered necessary to restore the second molar and improve the occlusal relationship with the first molar to recover occlusal function on the right side. After orthodontic therapy to correct the position of the mesially inclined tooth, occlusal restoration was carried out by dental implant treatment. The patient's clinical condition has remained excellent at over 5 years 2 months post-surgically and the patient is satisfied with the treatment outcome. The combination of dental implant treatment and orthodontic therapy were effective in improving the intraoral environment in this patient, indicating the efficacy of interdisciplinary treatment planning and practice.

A case of Sotos syndrome treated with distraction osteogenesis in maxilla and mandible.

Sotos syndrome is inherited in an autosomal-dominant manner and is characterized by increased birth weight, excessive growth, advanced bone age, and distinctive facial features, including dolichocephaly, hypertelorism, and a prominent mandible. We treated a jaw deformity due to Sotos syndrome consisting of malocclusion due to a narrow maxillary dental arch and mandibular retrusion from hypoplasia of the rami. The patient was a 17-year-old man. Malocclusion due to a narrow maxillary dental arch and mandibular retrusion was diagnosed. Rapid maxillary expansion with Lines corticotomy and mandibular advancement with distraction osteogenesis were performed. The maxilla was expanded laterally a total of 3 mm and the mandible prolonged 12 mm in the posterior area of the mandibular body. Subsequently, orthodontic treatment was continued. At present, 5 years after surgery, occlusion remains good and stable.

Case reports of orthodontic treatment of maxillary central incisors with short roots.

Maxillary central incisors with short roots are occasionally encountered during orthodontic diagnosis. From an esthetic point of view, the central incisors occupy the most noticeable position in the maxillary and mandibular arches, and whether or not to extract them marks a major turning point in the planning of orthodontic treatment. In deciding a treatment strategy in this situation, there are two options to be considered: 1) treatment without extraction due to esthetic considerations; or 2) extraction, taking risk and prognosis into account. Whichever strategy is adopted, however, it will still be necessary to bear in mind that the treatment and prognosis will differ from that in normal orthodontic treatment. If no extraction is to be carried out, care must be taken that no further shortening occurs during the course of active treatment and that stable retention is preserved. On the other hand, if the central incisors are to be extracted, care must be taken to ensure that this has no negative esthetic impact, either during or after orthodontic treatment.

Stress distribution in mandible and temporomandibular joint by mandibular distraction: a 3-dimensional finite-element analysis.

The effects of mandibular distraction on the mandible and its surrounding tissue remain to be clarified. Here, we used a 3-dimensional finite-element method to investigate the effects of unilateral horizontal lengthening of the mandibular body and vertical lengthening of the mandibular ramus on the mandible and temporomandibular joint (TMJ). With horizontal loading that assumed mandibular body lengthening, tensile and compressive stresses were great near the anterior region of the mandibular angle (the loading area). With vertical loading that assumed mandibular ramus lengthening, tensile and compressive stresses were great at the center of the mandibular ramus (the loading area). Under both loading conditions, stress distribution in the TMJ was greater on the loading side than on the non-loading side. With mandibular body lengthening, the center of the mandible deviated in the direction of the non-lengthened side to widen the mandible in the lateral direction. With mandibular ramus lengthening, the occlusal plane tilted in the inferior direction on the lengthened side. In the TMJ, stress was greatest on the affected side during mandibular ramus lengthening, suggesting the need to consider the mandibular condyle on the affected side during this procedure.

Clinical statistical investigation of cleft lip and palate patients aged over 18 years at Department of Orthodontics, Suidobashi Hospital, Tokyo Dental College.

Since the fee for orthodontic treatment of malocclusion caused by cleft lip and palate (CLP) became covered by national health insurance in 1982, orthodontic treatment from school age has become the norm. However, in some CLP patients, orthodontic treatment is commenced in adulthood. A number of studies have reported on orthodontic treatment in adult CLP patients. The purpose of this study was to clarify the number and age of new patients, chief complaint, referral status, cleft type, malocclusion, history of orthodontic treatment, and acceptance and planning of orthodontic treatment. The study investigated new CLP patients aged over 18 years who visited the Department of Orthodontics, Suidobashi Hospital of Tokyo Dental College, between April 1, 2001 and March 31, 2006. During the investigation period mentioned above, 235 new CLP patients visited our department. Among them, 23 were aged over 18 years, accounting for 9.8% of the 235 CLP patients. In terms of chief complaint, occlusion-related complaints and occlusal dysfunction accompanying malocclusion were noted in 14 cases (61%). Eighteen patients were referrals. Unilateral CLP was the most prevalent cleft type. In terms of malocclusion type, reversed occlusion was noted in 13 cases (57%), accounting for over half of all cases. Patients with a previous history of orthodontic treatment accounted for half of all cases. Ten patients accepted orthodontic treatment. In terms of treatment plan, surgical orthodontic treatment was planned in 10 cases.

Changes in orthodontic cephalometric reference points on application of orthopedic force to jaw: three-dimensional finite element analysis.

The present study investigated the effects of two orthodontic appliances on changes in the cephalometric reference planes using the three-dimensional finite element method. We simulated the use of a headgear and an orthopedic facial mask, two devices for the application of orthodontic force to the jaw. Using a finite element model of the skull, orthodontic force was applied to the maxillary first molar in a posterior or anterior direction. Changes in the maxilla, mandible and cephalometric reference planes were ascertained by the three-dimensional finite element method. The results showed that posterior force caused a slight posterior displacement and clockwise rotation of the reference planes, while anterior force caused anterior displacement and counterclockwise rotation. Since the maxilla was displaced and rotated in the same direction, the degrees of cephalometric displacement and rotation of the maxilla were smaller than the actual values.