The maxillary sagittal appliance: a clinical study

A clinical review of the maxillary sagittal appliance is presented. The appliance is an active plate with expansion screws in the anteroposterior direction, hence the name. It is used to advance the maxillary incisors and to distalize the maxillary molars, thereby increasing arch length. No control or reference group was used. The maxillary incisors were advanced approximately 2 mm and the inclination was increased approximately 8 degrees. Cephalometrically, the maxillary molars were not distalized, possibly because no second molars were extracted. A minor advancement was noted at A point and the upper lip was advanced 1.4 mm. Very little change was noted in the mandibular dentition or mandibular skeletal measurements except for the overall mandibular length, which increased 3.00 mm during the 7.4 months of average treatment time. The lower anterior facial height increased 2.85 mm, which was more than expected and many contraindicate the appliance in long-faced patients. The appliance is easy to manage clinically and provides another appliance that may be used to decompensate the maxillary teeth before functional jaw orthodpedic (FJO) therapy or fixed therapy in Class II, Division 1 or Class II, Division 2 patients with a flat or recessive upper lip.     

Patterns of bilateral agenesis of maxillary third molars and agenesis of other teeth

The purpose of this study was to investigate the patterns of bilateral agenesis of maxillary third molars and other tooth agenesis in Japanese orthodontic patients. A group of 262 subjects with bilateral agenesis of maxillary third molars (group A) was divided into three subgroups: group 1A consisting of 114 subjects without agenesis of mandibular third molars; group 2A, 31 subjects with unilateral agenesis of mandibular third molars; and group 3A, 117 subjects with agenesis of all third molars. As controls, 926 other subjects without third molar agenesis were selected (group C). Panoramic radiographs were mainly used to examine for tooth agenesis. The Chi square test and odds ratio were used to make statistical comparisons. The prevalence rates of agenesis of maxillary lateral incisors, mandibular incisors and maxillary and mandibular second premolars, and bilateral agenesis of maxillary lateral incisors and second premolars were significantly higher in any one of the third molar agenesis groups than in the control group. Characteristically, no significant increase in occurrence of bilateral agenesis of mandibular second premolars was demonstrated by the subjects with bilateral agenesis of maxillary third molars. Irrespective of whether unilateral or bilateral agenesis of mandibular third molars is present or not, the Japanese orthodontic patients with bilateral agenesis of maxillary third molars exhibited a significantly increased occurrence of unilateral or bilateral agenesis of maxillary lateral incisors, mandibular incisors and maxillary and mandibular second premolars, except for bilateral agenesis of mandibular incisors and second premolars.     

Stress distribution produced by correction of the maxillary second molar in buccal crossbite

The purpose of this study was to evaluate the stress distribution produced in the dentoalveolar system by a maxillary posterior crossbite appliance used for the correction of maxillary second molars in buccal crossbite. A photoelastic model was fabricated using a photoelastic material (PL-3) to simulate alveolar bone and ivory-colored resin teeth. The model was anteriorly and posteriorly observed with a circular polariscope and photographically recorded before and after activation of the maxillary posterior crossbite appliance. An uncontrolled palatal tipping and a rotating force were generated when the traction force was applied on the palatal surface of the maxillary second molar. A controlled tipping and an intrusive force were generated when the traction force was applied on the buccal surface of the maxillary second molar.     

A 2-stage procedure combining maxillary advancement by distraction technique with mandibular setback surgery in patients with cleft lip and palate

A 2-stage procedure combining maxillary advancement by distraction technique with mandibular setback surgery was used to correct jaw deformities in 5 patients with severe maxillary retrusion secondary to cleft lip and palate. First, a Le Fort I maxillary osteotomy was performed. Immediately after maxillary distraction, the distraction device was removed. The advanced maxilla was fixed with miniplates after adjusting the length and direction of advancement, and mandibular setback surgery was performed simultaneously to obtain a normal occlusal relationship. This 2-stage procedure resulted in stable occlusion and a markedly improved facial profile.     

Maxillary advancement with internal distraction device in cleft palate patients

This study aimed to evaluate the results of maxillary advancement by using internal Le Fort 1 distractors on six patients with unilateral cleft lip and palate who had maxillary hypoplasia.The retrognathic maxilla of five patients were protracted with distractor bilaterally, and asymmetric advancement was performed in one patients. A removable intraoral acrylic appliance was used as an anchorage appliance in two patients, and Ragno fan-type expander appliance was used in the others to prevent maxillary collapse during the distraction period. The maxilla of one patient was not distracted successfully due to the maxillary collapse in result of breaking the removable anchorage appliance away. Lateral cephalograms were evaluated before 3 and 12 months after distraction.A desired level of advancement was attained in five patients. In one patient distraction was not performed due to the maxillary collapse. In one of the five patients with a wide oronasal fistula, the size of the fistula was decreased with asymmetric advancement of right and left maxillary segments. Following the retention period of 12 months, the results were stable.It was concluded that effective and easy distraction is possible with internal Le Fort 1 distractors in cleft lip and palate patients who requires maxillary advancement.     

Comparison of the midline stress fields in maxillary and mandibular complete dentures: a pilot study

STATEMENT OF PROBLEM: Complete dentures typically fracture along the midline due to crack initiation and propagation from stressed areas. Therefore, it is important to characterize the magnitude and direction of maximum stresses developed in the midline of dentures. PURPOSE: The purpose of this pilot study was to determine the midline stress field of a mandibular complete denture under different loading conditions, and to compare this with the corresponding field of a maxillary denture to identify whether significant differences in maximum stresses between these 2 stress fields are responsible for the higher rate of failure seen clinically in maxillary dentures. MATERIAL AND METHODS: The identical casts used in this study were fabricated with commercial molds. Two complete acrylic resin dentures (1 maxillary and 1 mandibular) that were used in a previous study were selected as prototype dentures for this study. The mandibular acrylic denture was used to fabricate a 2-piece mold from silicone (upper half) and polymethyl methacrylate (PMMA) sheets (lower half) that was subsequently used to produce 3 identical mandibular complete dentures. The single maxillary acrylic denture was used to load the mandibular dentures. A rosette strain gauge was cemented onto the midline of each of the 3 mandibular dentures. The test conditions, including the fabrication of the casts used to induce loads, simulation of oral mucosa, loading procedure, strain measurement, and stress calculations, were identical to those used in a previous investigation of maxillary complete dentures to allow a direct comparison between maxillary and mandibular dentures. The Mann-Whitney test (alpha=.05) was used to quantify the differences in the stress magnitudes between maxillary and mandibular complete dentures. RESULTS: The stresses in the mandibular denture differed both qualitatively and quantitatively from those in the maxillary denture. The midline stress field of the mandibular complete denture was characterized by 2 low compressive principal stresses and a low maximum shear stress, whereas the corresponding stress field of the maxillary complete denture was characterized by a high principal tensile stress and a high shear stress. These differences between the stresses of maxillary and mandibular dentures were statistically significant (P<.001). CONCLUSION: The differences in stress patterns between mandibular and maxillary complete dentures as determined by this study, which also used data from a previous study, may be the primary reason why maxillary dentures fracture more often than mandibular dentures.     

The influence of dentures on nasalance values in speech.

OBJECTIVE: The purpose of this study was to investigate the effects of maxillary dentures on nasalance values in normal elderly individuals. DESIGN: A three-factor within-subjects experimental design was employed to analyze the nasalance scores obtained. PARTICIPANTS: Twenty English-speaking women aged 61 to 81 years, who wore complete maxillary dentures, participated in the study. INTERVENTION: A Nasometer was used to collect nasalance data. Participants read three standard passages aloud, three times each, in two conditions: with and without their maxillary dentures. RESULTS: Results revealed that nasalance values were significantly lower with the maxillary dentures removed (p<.01), although the difference in nasalance between the two denture conditions averaged no more than 2%. Nasalance scores obtained both with and without maxillary dentures fell within one standard deviation of the mean for a reference group of comparably aged English-speaking women. CONCLUSIONS: The results suggest that the existing collection of normal reference data for nasalance may be safely used for elderly individuals regardless of their status with respect to natural or prosthetic maxillary dentition.     

Statistical evaluation of possible factors affecting the sagittal position of the first permanent molar in the maxilla

A cephalometric analysis was designed to evaluate several factors that may affect the sagittal position of the maxillary first permanent molar. A total of 184 Class II and Class I malocclusion patients were randomly selected before orthodontic treatment. The mandibular and palatal planes were related to Frankfort Horizontal and used to create the interjaw or B angle. Age and cephalometric landmarks (Ba, N, point A, pterygomaxillary fissure, and maxillary molars) were projected at right angles to the Frankfort Horizontal for effective length. Actual maxillary length and actual molar location were determined by projecting landmarks at right angles to the palatal plane. Correlation coefficients and P values were used to evaluate the data with a minimal significance value of .05 to determine a 95% confidence level. A statistically significant linear and proportional positive correlation (P < .0001) existed between molar location, age, and maxillary size. There was a strong negative correlation (P < .0001), both linearly and as a proportion of the actual length of the maxilla, between the actual position of the maxillary molar and the interjaw and mandibular plane angles. A significant correlation also existed between the molar position and palatal plane angles. The results show that increased interjaw, mandibular, and palatal plane angles are accompanied by a more posterior position of the maxillary first molar in the maxilla, whereas the molar occupied a continuing more forward position in the maxilla with increasing age, cranial base length, and maxillary size.     

A lip-activated appliance in early orthodontic treatment

After reviewing the modes of action and types of lip-activated appliances, three cases were reported. A mandibular lip-activated appliance was used to gain space among the incisors and mesial to the mandibular permanent first molars; a maxillary lip-activated appliance was used to correct an anterior crossbite by labial movement of the incisors; and a modified lip-activated appliance was used to expand maxillary molars buccally.     

Treatment of space loss caused by submerged maxillary second primary molar

Submersion is a clinical term describing a tooth depressed below the occlusal plane. In this case report, we present the treatment of a patient who had totally submerged primary maxillary second molar, which caused impaction of the second premolar and space loss in the maxillary arch due to tipping of adjacent teeth. A 12-year-old girl was referred to the pediatric dentistry clinic. The intra-oral examination revealed that right maxillary second primary molar was localized buccal side of posterior maxillary alveolar process, being almost completely covered by gingiva and adjacent teeth inclined closing the space of the related teeth completely. Periapical radiograph demonstrated that maxillary second premolar was impacted. Based on clinical and radiographic findings, maxillary primary second molar was extracted. Headgear was used for the distalization of maxillary right first molar in order to create space for the impacted second premolar. Eruption begun spontaneously 6 months later.     

上颌快速扩展最佳时机的初步研究

目的:通过患者年龄、牙龄、骨龄,对上颌快速扩展扩弓效应的相关性分析,期望发现应用上颌快速扩展的最佳时机。方法:选择需上颌横向扩展的患者30例,年龄11～14岁,平均12.30岁,进行上颌快速扩展。摄左手腕掌指骨片,扩展矫治前后的上颌前部咬合片、头颅正位定位片。利用SPSS11.0软件包对数据进行t检验、多元线性回归、多元逐步回归分析。结果:年龄相近,扩展效应不一;骨龄与扩展效应具有一定的相关性,偏回归系数为-6.440,P值为0.045;牙龄与扩展效应具有高度相关性,偏回归系数为-1.289,P值为0.000。随着上颌第二恒磨牙的萌出、生长和建牙合,扩展效应明显下降。结论:在上颌第二恒磨牙萌出前进行上颌快速扩展,可在较短的治疗时间内获得所需的骨骼效应。     

波及上颌窦的大型颌骨囊肿的治疗及临床效果

目的:探讨侵犯上颌窦的大型颌骨囊肿的治疗和临床效果。方法 :回顾2007-07—2015-03期间,在本院治疗的72例侵犯上颌窦的颌骨囊肿患者。A组(n=36)术中联合用超声骨刀和鼻内镜,彻底清除病变组织,保存正常窦内黏膜及骨骼外形;B组(n=36)术中用骨凿、咬骨钳去除骨壁,摘除囊壁组织后用刮匙搔刮囊腔及行上颌窦根治术。术后随访观察3~72个月,对术后并发症进行对比观察和统计学分析。采用SPSS13.0软件包对数据进行χ2检验。结果:A组患者在上颌窦瘘、面部畸形、鼻通气功能方面,术后并发症发生率显著低于B组(P<0.05);颌面部的美观和功能恢复良好。结论:术中用超声骨刀和鼻内镜治疗侵犯上颌窦的大型颌骨囊肿,保存正常窦内黏膜及骨骼外形,可明显降低上颌窦瘘和鼻通气下降的发生,颌面部的美观和功能恢复较满意。     

The maxillary rotation: Its relation to the cranial base and the mandibular corpus An implant study

A material of 22 patients with metallic implants was used in a longitudinal study, based on lateral head-plates, of the relationship between: 1) the maxillary rotation and the cranial base 2) the maxillary rotation and the different mandibular rotations. No connection has been found between the variation of the maxillary rotation and the growth of the cranial base. The correlation between the maxillary and the mandibular rotations is the highest when the rotation of the corpus is considered. A strong correlation is found between the variation of the condylar growth direction and the variation of the maxillary rotation.     

The maxillary rotation: Its relation to the cranial base and the mandibular corpus. An implant study.

A material of 22 patients with metallic implants was used in a longitudinal study, based on lateral head-plates, of the relationship between: 1) the maxillary rotation and the cranial base 2) the maxillary rotation and the different mandibular rotations. No connection has been found between the variation of the maxillary rotation and the growth of the cranial base. The correlation between the maxillary and the mandibular rotations is the highest when the rotation of the corpus is considered. A strong correlation is found between the variation of the condylar growth direction and the variation of the maxillary rotation.     

多曲余弦函数模拟上颌前部弓形宽度、深度和弧长之间的相互关系

目的：探讨上颌尖牙间宽度（W）、前牙弓深度（D）与前牙弓周长（L）之间的相互关系及其对咬合的影响。方法t利用多曲余弦函数描述前部牙弓的形态,建立数学模型来编程计算三者间的关系。结果：在D不变时,W每增加1mm将提供约0．8mm的L;D每减小或增大1mm,需要W增大或减小约1．8—2．0mm;在一定程度上,上下牙量的不调可通过调整W来缓解、消除。结论：在精细调整阶段,应注意W、D与L之间相互关系的变化对最终良好殆关系建立的影响。     

Three-dimensional in vitro measurement of initial forces and moments acting on maxillary canine teeth using various Class II elastic configurations with a straight archwire fixed lingual appliance

PurposeThe presented study utilized an in vitro Orthodontic SIMulator (OSIM) to study how Class II elastic configuration effects the forces and moments acting on maxillary canine teeth when using a straight archwire fixed lingual appliance.Materials and methodsMaxillary in-Ovation L self-ligating brackets were bonded to anatomically shaped stainless steel teeth on OSIM. A 0.016″ × 0.022″ stainless steel straight lingual archwire was used to provide a relevant arch shape and to position simulated teeth in a passive position. A mandibular typodont was positioned above the OSIM arch in a half cusp Class II malocclusion to serve as attachment points for elastics. Four different elastic configurations were tested: 1. maxillary–buccal to mandibular-buccal; 2. maxillary–lingual to mandibular–lingual; 3. maxillary–buccal to mandibular–lingual; 4. maxillary–lingual to mandibular–buccal. A new 4.5 oz 3/16″ elastic (n = 40 per configuration) was attached to the maxillary canine and mandibular first molar teeth for each trial. Forces and moments at the maxillary canine simulated center of resistance were considered. ANOVA was used to assess the effect of elastic configuration, and pairwise comparisons using Bonferroni correction were conducted to investigate configuration differences.ResultsOf the thirty-four pairwise comparisons, only two were statistically insignificant. Configurations 1, 2, and 4 were found to produce over 1 N of force in the desired distal direction, whereas Configuration 3 was significantly lower at 0.65 N.ConclusionsOverall, the configuration of Class II elastics had a significant effect on forces and moments at maxillary canine teeth for a simulated straight archwire fixed lingual appliance.     

两种不同扩弓方法结合上颌前方牵引的初步研究

目的探索反复快速扩弓回缩结合上颌前方牵引的可行性和方法,对比上颌单次快速扩弓和反复快速扩弓回缩结合前方牵引治疗的效果。方法选择20例上颌后缩患者,每组10例。A组：上颌单次快速扩弓加前方牵引,B组：上颌反复快速扩弓回缩加前方牵引。对治疗前及前方牵引6个月后的头颅侧位片进行头影测量分析。结果两组病例扩弓并前方牵引6个月后上颌显著前移和逆时针旋转,下颌向后下方旋转,上切牙唇倾、下切牙舌倾。两组间对比：反复扩弓回缩组前方牵引后上颌前移量（A点3．56mm）显著大于单次扩弓组（A点2．12mm）。结论使用上颌反复扩弓回缩结合前方牵引的方法治疗上颌后缩患者是可行的,其对前移上颌的效果优于单次扩弓结合前方牵引治疗。     

Variations of Palatal Canal Morphology in Maxillary Molars: A Case Series and Literature Review

A series of challenging cases with unusual canal anatomy in the palatal roots of maxillary first and second molars is presented. A review of the literature was done to elucidate the prevalence of anatomic variations in the palatal canal of maxillary first and second molars. An uncertain or indefinite radiographic appearance of the palatal canal, or eccentric deviation of the master cone or previous root canal filling was considered an indication of a bifurcated palatal canal. Five maxillary molars with a bifurcated palatal canal were identified. A MEDLINE database search was performed to identify studies on the palatal canal morphology of maxillary first and second molars. Data were categorized based on the methodology used in each study. The overall prevalence of anatomic variations in the palatal canal of maxillary first and second molars was less than 2%; however, anatomic variations occurred more frequently in certain ethnic groups, reaching up to 33% in maxillary first molars and up to 14% in maxillary second molars. This case series showed that even experienced endodontic clinicians can miss a bifurcated palatal canal if they are not aware of or overlook the hidden clues for these anatomic variations. The traditional assumption of an exclusively single-canal anatomy in palatal canals of maxillary molars needs to be changed, even though it is the most prevalent anatomy. The overall low percentage of more than 1 palatal canal in maxillary molars is disturbingly misleading, because in certain ethnic groups this prevalence can be considerably higher.     

Simultaneous maxillary advancement and closure of bilateral alveolar clefts and oronasal fistulas

A technique for simultaneous maxillary advancement with closure of alveolar clefts and oronasal fistulas in the patient with secondary cleft deformities and a Class III pattern of malocclusion resulting from maxillary hypoplasia is described. A case in which this technique was used is reported.     

Osseointegrated titanium implants for maxillofacial protraction in monkeys

Titanium implants were placed surgically into the maxillary, zygomatic, frontal, and occipital bones of four pigtail monkeys. After a 4-month healing period, the implants were exposed and abutments were placed. Extraoral traction appliances were then attached to the abutments. The cranial implants were used to support the framework of the traction appliance; those in the facial bones were used to attach springs that delivered a protraction force. The application of force varied among animals. In animal A, the force was applied to the maxilla. In animal B, the force was applied to the zygomatic bones. Animals C and D had force applied to both the maxillary and zygomatic bones. A tensile force of 600 gm per side was maintained until approximately 8 mm of maxillary anterior displacement had occurred. This amount of movement required 12 weeks of force application in animals A and B, and 18 weeks in animals C and D. Cephalometric and dry skull analyses showed that the amount of skeletal protraction was significant. The findings also demonstrated that it was possible to control the direction of maxillary protraction. The facial implants remained immobile throughout the experiment.