Longitudinal study of functional conditions in the masticatory system in Flemish children

A 5-yr longitudinal study on occlusal and functional parameters has been made in 75 children aged 8-11. They were selected at random from an original group of 510 studied 5 yr earlier. The following parameters were measured: frequency of frontal open bite lateral and frontal crossbite, the attrition on molars and on front teeth, the contacts on lateral excursion, pain on condyle palpation, TMJ clicking, deviations in the opening and lateral movement, and the maximal interincisal distance. There was an increase in the percentage of deep bite and crossbite. Attrition on molars was seen in 41% and on front teeth in 13% of the children. No real pattern could be observed as a function of age. The mean maximal opening range was 43.7 mm, varying between 23 and 52 mm. Restricted opening was found in one girl. In 60% a deviation in the opening has been found. In 26% TMJ sounds were observed and 28% had pain on condyle palpation. In most of the children the symptoms were very mild to moderate. No significant correlation could be found between dysfunctional signs and occlusal parameters. The present results did not provide any conclusive answer to the tremendous increase in dysfunctional signs over this 5-yr period. The treatment need is, however, low and should not be overestimated.     

Indication for and Frequency of Early Orthodontic Therapy or Interceptive Measures

The early treatment of nonskeletal and skeletal orthodontic anomalies in the deciduous and early mixed dentition is intended to prevent the development of pronounced anomalies in the late mixed and permanent dentition with the ultimate aim of reducing or even eliminating the need for later orthodontic treatment. There is a general consensus in the international literature that early therapy is indicated in cases of anterior and lateral crossbite and Class III malocclusion, and possibly for extreme forms of mandibular retrognathism (overjet > or =10 mm) and of open bite. However, evidence of the efficiency of early orthodontic measures is just as rare as studies providing serviceable information on the incidence of tooth malalignments and malocclusions in the deciduous and early mixed dentition, some of whose findings are in any case highly divergent. This makes it substantially more difficult to draw conclusions on the extent to which early orthodontic therapy may be indicated. In order to obtain information on the incidence of nonskeletal and skeletal orthodontic problems constituting a treatment need, 2326 first-year schoolchildren aged between 6 and 7 years were examined in Frankfurt am Main and in the Rural District of Offenbach. In only 14.7% of the children were no relevant orthodontic findings recorded. 77.2% displayed mild to severe dysgnathic symptoms, though without early orthodontic therapy being considered indicated. Treatment with orthodontic appliances was considered urgent for 187 of the children (8.04%). With 8.3% and 7.9% respectively, lateral and anterior crossbite were top of the list of anomalies with an urgent treatment need. Among the patients with lateral crossbite, the prognostically less favorable unilateral form was recorded approximately four times more often than the bilateral form. Markedly increased sagittal overjet > or =10 mm) was registered in only 1.4% of the children, and negative overjet (Class III) (with the exception of edge-to-edge bite) in 1.9%. Extreme anterior open bite > or =6 mm) was recorded in only two children (0.09%). In 19.6% of the children, a supporting zone was reduced in at least one quadrant, necessitating interceptive measures such as the insertion of a space maintainer or later orthodontic treatment (space opening or extraction therapy).     

Use of a new instrument for lateral release in arthroscopic surgery of the temporomandibular joint: a preliminary study

We developed a new instrument, which we call a lateral releaser, to improve the safety of either a blind lateral release or lateral stretching within the TMJ We used it during arthroscopic surgery in patients with chronic painful hypomobility of the temporomandibular joint (TMJ). We operated on 24 TMJs in 17 patients (15 women and 2 men). At operation, the mean increase in the interincisal distance was 22 mm (range 10-32). No instruments were broken. No serious surgical complications were reported during or after operation. Many of the patients currently have an interincisal distance exceeding 38 mm.     

Ankylosis of the temporomandibular joint developing shortly after multiple facial fractures

A 41-year-old male patient was referred for treatment of extensive facial fractures and lateral condylar dislocations. The patient underwent open reduction and fixation under general anaesthesia. Intermaxillary fixation was released in 2 weeks and mouth opening was 21 mm. Despite postoperative physical exercises, the range of motion decreased to 10 mm at 5 weeks after the surgery. MR arthrography revealed a fibrous ankylosis in the bilateral TMJs. Coronal CT scans depicted a bony outgrowth of the left TMJ tuber. The patient underwent surgery for the ankylosis including discectomy and coronoidectomy, and removal of the bony outgrowth. An interincisal distance of 30 mm on maximal mouth opening has been maintained for 14 postoperative months. The importance of imaging assessment was emphasized for diagnosing the precise pathologic state of the ankylosis and selecting an appropriate surgical treatment of choice.     

Mandibular condyle lesions, jaw movements, and occlusal status in 15-year-old children with juvenile rheumatoid arthritis

The purpose was to determine the number and severity of lesions in the temporomandibular area and their association with occlusal status and mandibular movements in 15-yr-old children afflicted with juvenile rheumatoid arthritis (JRA). The series comprised 121 JRA children, 78 girls and 43 boys, and a control group of 104 schoolchildren, 70 girls and 34 boys, taken for clinical examination. Of the JRA children, 55% had roentgenologically detectable lesions in the TMJ area. Lesions were found in 60% of the girls and in 42% of the boys, the ratio thus being 3:2. The largest group had grave lesions (48%), the second largest displayed flattening of the condyle (43%) and the smallest a flattened condyle with a minor lesion (9%). There were more bilateral lesions in the children with the severest lesions. Tendencies for Class II malocclusion, small vertical overbite and open bite were visible in the JRA children. Reduced maximal opening capacity, maximal protrusion, lateral movements of the mandible and pain in the TMJ area proved to be reliable signs predicting temporomandibular joint involvement in JRA children. Maximal mouth opening capacity was significantly restricted in the patients showing condylar lesions as compared with patients having no lesions or with controls. JRA children should be divided according to sex and the severity of the lesions. The JRA children without TMJ lesions had normal values for mandibular movements and were thus comparable to healthy children.     

Mandibular condyle lesions, jaw movements, and occlusal status in 15-year-old children with juvenile rheumatoid arthritis

Abstract – The purpose was to determine the number and severity of lesions in the temporomandibular area and their association with occlusal status and mandibular movements, in 15-yr-old children afflicted with juvenile rheumatoid arthritis (JRA). The series comprised 121 JRA children, 78 girls and 43 boys, and a control group of 104 schoolchildren, 70 girls and 34 boys, taken for clinical examination. Of the JRA children, 55% had roentgenologically detectable lesions in the TMJ area. Lesions were found in 60% of the girls and in 42% of the boys, the ratio thus being 3:2. The largest group had grave lesions (48%), the second largest displayed flattening of the condyle (43%) and the smallest a flattened condyle with a minor lesion (9%). There were more bilateral lesions in the children with the severest lesions. Tendencies for Class II malocclusion, small vertical overbite and open bite were visible in the JRA children. Reduced maximal opening capacity, maximal protrusion, lateral movements of the mandible and pain in the TMJ area proved to be reliable signs predicting temporomandibular joint involvement in JRA children. Maximal mouth opening capacity was significantly restricted in the patients showing condylar lesions as compared with patients having no lesions or with controls. JRA children should be divided according to sex and the severity of the lesions. The JRA children without TMJ lesions had normal values for mandibular movements and were thus comparable to healthy children.     

Effects of nonnutritive sucking habits on occlusal characteristics in the mixed dentition

PURPOSE: Little is known about the extent to which nonnutritive sucking habits contribute to malocclusion in the mixed dentition. The purpose of this study was to report on the relationship between certain occlusal traits in the mixed dentition and longitudinal sucking behaviors. METHODS: Dental examinations were conducted on 630 children in the mixed dentition who participated in a large, ongoing longitudinal study. Five hundred eighty consented to impressions, and 524 adequate study models were obtained. Of these, 444 also had adequate longitudinal nonnutritive sucking data obtained via mailed questionnaires to parents at 3- to 6-month intervals from birth to 8 years. Sucking behaviors were grouped by predominant type and duration. Study models were hand articulated using wax bites to evaluate the occlusion for the presence of open bite, crossbite, molar relationship, and excessive overjet. Bivariate statistical analyses related presence of these malocclusions to sucking duration and type. RESULTS: Fifty-five percent of the children had malocclusions (anterior open bite, posterior crossbite, bilateral Class II molar relationship, or overjet >4 mm). Class II molar relationship was most common (30%). Overall, anterior open bite and posterior crossbite was associated with habits of 36 months or more. Sustained pacifier habits, including those of 24 to 47 months, were associated with anterior open bite and Class II molar relationships, while digit habits were associated with anterior open bite when sustained for 60 months or longer. CONCLUSIONS: Malocclusions are quite prevalent in the mixed dentition, and anterior open bite and posterior crossbite may be preventable by modifying nonnutritive sucking behaviors.     

关节盘复位在创伤性颞下颌关节强直治疗中的作用

目的　探讨创伤性颞下颌关节强直关节成形术中关节盘复位的手术方法及其临床效果。方法　 19例创伤性颞下颌关节强直患者接受关节成形术时进行了关节盘复位。术中在关节附近寻找分离出移位的关节盘并将其复位至髁突顶端的解剖位置 ,最后将关节盘的外侧端缝合固定至颧弓根部的软组织。结果　平均随访 2 3 7个月 ,患者的张口度为 2 4～ 4 3mm (平均为 32 6mm) ,所有的患者张口度均接近或达到正常 ,无关节疼痛及弹响症状 ,随访期内无一例患者复发。结论　在创伤性颞下颌关节强直的治疗中 ,关节盘复位可行有效 ,是重建关节结构、恢复关节功能和预防复发的好方法。     

Prevalence of malocclusions in the 13-20-year-old categories of football athletes

The dentist can offer athletes improvement in their physical performance through the maintenance of oral health, preventing and treating any and all changes in the stomatognathic system, such as dental malocclusions, that compromise the athletes' performance. The objective of this study is to research the presence of dental malocclusions in athletes of the category between 13 and 20 years of age, from the S?o Paulo Football Club. 84 athletes participated in this study, dealing with the following topics: molar relation (Angle's classification); presence of overbite; underbite; overcrowding; abnormal spacing; open bite; and anterior, posterior, bilateral and unilateral crossbite; midline deviation and facial type (mesofacial, brachyfacial and dolichofacial). Only one table was made, showing percentages. In regard to Angle's molar relation, 89% are in Class I, 8% in Class II, 3% Class III, 9% of the athletes had overbite, 4% had underbite, 13% had overcrowding and 21% had abnormal spacing. In regard to the bite, 11% presented anterior open bite. In regard to crossbite, 7% presented unilateral crossbite on the right side and 2% on the left side; 5% presented posterior crossbite and 4% anterior crossbite. In regard to midline deviations, 4% presented deviation in the maxilla and 33% in the mandible. In regard to facial type: 39% are dolichofacial, 4% brachyfacial and 57% mesofacial. Based on the results shown, proposals for the implementation of dental, phoniatric, and Ear, Nose and Throat (ENT) practices are already being discussed with the multidisciplinary team of the club involved.     

Prevalence of temporomandibular dysfunction and its association with malocclusion in children and adolescents: an epidemiologic study related to specified stages of dental development

A sample of 4724 children (2353 girls and 2371 boys) (5-17 years old) were grouped not only by chronological age but also by stage of dental development (deciduous, early mixed, late mixed, and permanent dentition). The registrations included functional occlusion (anterior and lateral sliding, interferences), dental wear, mandibular mobility (maximal opening, deflection), and temporomandibular joint and muscular pain recorded by palpation. Headache was the only symptom of temporomandibular dysfunction (TMD) reported by the children. The results showed that one or more clinical signs were recorded in 25% of the subjects, most of them being mild in character. The prevalences increased during the developmental stages. Girls were in general more affected than boys. Significant associations were found between different signs, and TMD was associated with posterior crossbite, anterior open bite, Angle Class III malocclusion, and extreme maxillary overjet.     

JOINT DISORDER: NONREDUCING DISC DISPLACEMENT WITH MOUTH OPENING LIMITATION – REPORT OF A CASE

The internal derangement of the temporomandibular joint (TMJ) represents 8% of all cases of temporomandibular disorders (TMD) posing difficulties to establish an accurate diagnosis and treatment because of its low prevalence. This article presents the case of an 18-year-old Caucasian female patient who came to our Orofacial Pain and TMD Outpatient Service with complaints of intense pain on the right TMJ and limitation of mouth opening (maximum interincisal opening of 29 mm) with deviation to right, which she had been experiencing for the past 3 years. After a detailed clinical interview, a diagnosis hypothesis of nonreducing disc displacement with mouth opening limitation was established. The proposed treatment consisted of intra-joint infiltration with anesthetic in the right TMJ followed by jaw manipulation to recapture the articular disc, which was impeding the complete translation movement of the affected TMJ. After jaw manipulation, a new evaluation was done and showed the re-establishment of jaw dynamics with mouth opening and closing without deviation to the right side, clicking, opening limitation or pain. The patient was followed up at 6 months intervals. Two years after treatment, the patient was reevaluated and her mandibular range of motion without aid increased to 54 mm with no clicking, deviation to right, trismus or pain on the TMJ, indicating success of the treatment approach without recurrence of the pathology.     

Arthroscopic surgery for treatment of anterior displacement of the disc without reduction of the temporomandibular joint

The aim of this study was to investigate the clinical results and efficacy of an arthroscopic approach to correct anterior displacement of the disc without reduction of the temporomandibular joint (TMJ) with limitation of mouth opening. We studied 28 joints with internal derangement in 23 patients, all of whom had had arthroscopic surgery (lavage, lysis of adhesions in the superior compartment, incision parallel to the disc-synovial crease of the upper joint compartment, and pull back of the anteriorly located disc). Objective and subjective data (increase in maximal interincisal opening, magnetic resonance imaging, and visual analogue pain score, VAS) were collected preoperatively and at 7, 30, 60 days, and 6 months or more postoperatively. Maximal interincisal opening improved from a mean (SD) of 20.4 (±4.5) mm preoperative measurement to 38.9 (±3.2) mm by 6 months postoperatively where indicated in previous line. The VAS showed a significant improvement in pain score (p=0.0023). Sixty days postoperatively the positions of the discs in 14 of the TMJs had improved considerably. In 13 of the TMJs the positions had improved slightly. Only 1 of the TMJs had not improved at all. There were no complications in any patient. Our arthroscopic procedure is safe, minimally invasive, and effective for the treatment of patients with displacement of the disc anteriorly without reduction of the TMJ.     

Interrelation between Occlusal Findings and Orofacial Myofunctional Status in Primary and Mixed Dentition

AIM: It was the purpose of this study to analyze the relationship between selected types of malocclusion and specific types of static and dynamic orofacial dysfunction and to compare the results with subjects presenting regular occlusion. We aimed to identify which orthodontic and functional symptoms in early dentition would lead to malocclusion later on. SUBJECTS AND METHODS: Occlusal relations and myofunctional status were evaluated in 3,041 children. We diagnosed dynamic and static myofunctional disorders as well as oral habits by means of functional examinations. RESULTS: No orofacial dysfunctions were found in 11.2% of the children with primary dentition and in 10.2% of the children with early mixed dentition. We observed no correlation between the existence of distoclusion and functional disorders. Lateral crossbite in mixed dentition, as well as increased overjet and frontal open bite in primary and early mixed dentitions appeared significantly more frequently in children with orofacial dysfunctions. Individuals with frontal open bite, lateral crossbite, reduced and increased overjet presented static dysfunctions significantly more frequently than those in dentitions with normal occlusion. Dynamic dysfunctions were significantly more prevalent in subjects with frontal open bite and lateral crossbite than in those with normal occlusion. CONCLUSIONS: Our results enable us to prognosticate which children risk future orthodontic problems. Any child presenting one of the four occlusal disorders plus one static or two dynamic dysfunctions is a child more likely to develop orthodontic problems later on. Orthodontic prevention and early treatment must include functional rehabilitation so as to eliminate or at least diminish those factors causing undesirable developments.     

Psychologic implications of surgical-orthodontic treatment in patients with anterior open bite

Two hundred eighty-two patients who received surgical-orthodontic treatment to correct anterior open bite were retrospectively evaluated by interview and questionnaires to determine the motivation and expectations before treatment, experience during treatment, psychosocial impact, functional and esthetic results, and satisfaction. All patients underwent a Le Fort I osteotomy, and 126 patients also received a bilateral sagittal split advancement osteotomy. The mean follow-up was 6 years. The most important reasons for treatment, as cited by the patients, were biting and chewing problems (28%), dissatisfaction with facial appearance (26%), and symptoms of temporomandibular joint (TMJ) dysfunction (21%). Patients with anterior open bite had a critical attitude toward facial appearance; therefore, esthetic aspects should be taken seriously. The expectations on chewing ability, phonetics, nasal passage, and facial appearance were met by the treatment; however, expectations on TMJ function, interincisal relationship, and biting ability were not completely fulfilled. There was a subjective improvement of TMJ sounds in 27% and a worsening in 14% of the patients. Dysesthesia of the infraorbital nerve was noticed in 4% of patients and of the mental or inferior alveolar nerve in 23% of the patients. Chewing and biting abilities improved in 53% and 73%, respectively. Facial appearance, self-confidence, and social interaction had improved. Patients had expected more information before and psychologic support after treatment. Despite the relapse of open bite in 20% of the patients, 75% were satisfied with the dental and 85% with the facial appearance.     

Feeding and nonnutritive sucking habits and prevalence of open bite and crossbite in children/adolescents with Down syndrome

Objective:To analyze the influence of breastfeeding, bottle feeding, and nonnutritive sucking habits on the prevalence of open bite and anterior/posterior crossbite in children with Down syndrome (DS).Materials and Methods:A cross-sectional study was carried out in 112 pairs of mothers/children with DS between 3 and 18 years of age at a maternal/children''s hospital in Rio de Janeiro, Brazil. The children with DS were clinically examined for the presence of open bite as well as anterior and posterior crossbite. Information on breastfeeding, bottle feeding, and nonnutritive sucking habits was collected using a structured questionnaire. The control variables were age and mouth posture of children/adolescents and mother''s schooling. Statistical analysis of the data was performed using the chi-square test and multiple logistic regression.Results:The prevalence of anterior open bite was 21%, anterior crossbite was 33%, and posterior crossbite was 31%. The use of bottle feeding for more than 24 months (prevalence ratio [PR]  =  1.6) was associated with the occurrence of open bite. Having breastfed for less than 6 months (PR  =  1.4) and pacifier sucking for more than 24 months (PR  =  3.1) were associated with the prevalence of anterior crossbite. Finger sucking (PR  =  2.9) and the use of bottle feeding for more than 24 months (PR  =  2.6) were associated with posterior crossbite.Conclusion:The prevalence of open bite and crossbite in children with DS was associated with the use of bottle feeding and pacifier sucking for more than 24 months, breastfeeding for less than 6 months, and finger sucking.     

儿童功能性单侧后牙反患者的髁突对称性及矫治后髁突位置变化的研究

目的探讨儿童功能性单侧后牙反患者的髁突对称性及上颌扩弓治疗后髁突位置的变化。方法选择22例通过上颌扩弓成功矫治的功能性单侧后牙反儿童患者,男10例,女12例,年龄6.0-8.5岁,平均7.5岁作为实验组。另选择22例正常患者,男11例,女11例,年龄6.5-9.0岁,平均7.5岁作为对照组。反组矫治前后与对照组患者均拍摄曲面断层片和双侧闭口位矫正薛氏位片,测量髁突形态的不对称指数和髁突在关节窝中的相对位置。用SPSS 12.0软件进行统计分析。结果反组患者两侧髁突形态无明显不对称,与对照组相比,髁突高度(CH)、升支高度(RH)以及两者之和(CH+RH)的不对称指数均无统计学差异。反组矫治前(T1)两侧髁突在关节窝中的位置有明显差异,非反侧关节前间隙减小(P<0.05),上后间隙增大(P<0.05)。非反侧髁突在关节窝中的位置(R)相对反侧更加靠前(P<0.01)。矫治后(T2)双侧髁突位置变得相对对称。结论儿童功能性单侧后牙反患者的髁突形态相对对称,而髁突位置存在不对称性,说明下颌向反侧发生功能性偏斜,而这种偏斜并未导致髁突发生骨性不对称;正畸治疗可使两侧髁突位置更加协调。     

Movement of the lateral and medial poles of the working condyle during mastication in patients with unilateral posterior crossbite.

Patients with unilateral posterior crossbite often show reverse sequential jaw movement patterns on the frontal view during mastication on the crossbite side. Recent studies show that such patients are prone to suffer from temporomandibular joint (TMJ) disc displacement, particularly the lateral portion. The purpose of this study was to examine the movement of the lateral and medial poles of the working condyle during mastication in such patients. Subjects were 12 consecutive patients with unilateral posterior crossbites and without TMJ disc displacements and 12 normal subjects. An optoelectronic jaw-tracking system with 6 degrees of freedom was used to record the motion of the lateral and medial poles of the working condyle during mastication of standardized hard, gummy jelly. The data from the first 10 cycles were analyzed. The lateral and medial poles of the condyle on the crossbite side moved more in the medial direction and less in the lateral direction during mastication in the crossbite patients than the condyle in the normal subjects. The lateral pole of the working condyle moved more in the posterior and inferior directions and less in the anterior direction than the medial pole in all subjects. These results suggest that these condylar movements in patients with unilateral posterior crossbites might be related to the susceptibility to TMJ disc displacement, particularly the lateral portion.     

自体肋软骨和自体喙突移植在成人单侧颞颌关节强直治疗中的临床效果比较

目的：比较成人单侧颞颌关节强直髁突重建中自体喙突移植和肋软骨移植的临床效果。方法：选取32例自体喙突移植和28例自体肋软骨移植重建髁突的颞下颌关节强直病例,对其术前和术后的饮食分数、最大张口度、侧向运动、开口型偏斜、CT扫描影像学等方面进行评价。结果：两组患者的关节强直治疗均取得满意效果。在饮食分数、张口度、侧向运动、开口型偏斜和复发率等术前及术后的测量值中,两组间差异无统计学意义（P>0．05）,但两组病例中术后张口度、侧向运动及饮食分数均较术前有显著改善。肋软骨移植术中有3例患者出现了胸膜撕裂,6例患者出现了移植骨供区的暂时性疼痛。肋软骨移植及喙突移植术后分别有5例和3例患者的面神经颞支受到了损伤,3－6月内康复。喙突移植组中无关节强直复发,肋软骨移植组中有1例复发。结论：在颞下颌关节强直矫治中,自体喙突移植是一种较好的髁突重建骨移植材料。     

Tooth wear: prevalence and associated factors in general practice patients

Cunha‐Cruz J, Pashova H, Packard JD, Zhou L, Hilton TJ for Northwest PRECEDENT. Tooth wear: prevalence and associated factors in general practice patients. Community Dent Oral Epidemiol 2010; 38: 228–234. © 2010 John Wiley & Sons A/S Abstract – Objectives: To estimate the prevalence of tooth wear and to investigate factors associated with tooth wear in patients from general practices in the Northwest United States. Methods: Data on the diagnosis and treatment of oral diseases during the previous year were collected in a survey with a systematic random sample of patients (n = 1530) visiting general dentists from the Northwest Practice‐based REsearch Collaborative in Evidence‐based DENTistry (PRECEDENT) (n = 80). Prevalence ratios (PRs) of moderate to severe occlusal and incisal tooth wear by patient characteristics were estimated using cluster‐adjusted multiple binomial regression for adults (18+ years) and children/adolescents (3–17 years). Results: For adults, the mean number of teeth with wear facets was 5.4 [95% confidence interval (CI) = 4.6–6.2] and 51% of the adults had four or more teeth with wear. Participants 45–64 and 65+ years old were 1.3 (95% CI = 1.1–1.6) and 1.4 (95% CI = 1.1–1.8) times as likely to have 4+ teeth with moderate to severe wear facets as participants 18–44 years old. Adult males had a 20% (PR = 1.2; 95% CI = 1.1–1.4) higher prevalence of wear than adult females. Adults who were using, or had ever used occlusal splints had higher prevalence of tooth wear compared to those who never used such appliances (PR = 1.3; 95% CI = 1.0–1.5). Adults with any periodontal bone loss also had a 20% higher prevalence of wear than adults without periodontal disease (PR = 1.2; 95% CI = 1.0–1.4). For children/adolescents, the mean number of teeth with moderate to severe wear facets was 1.6 (95% CI = 0.9–2.6) and 31% of the children had one or more teeth with wear facets. The adjusted prevalence ratio of tooth wear (1+ teeth with wear facets) for boys was 1.6 times as high (95% CI = 1.1–2.4) as compared with girls. The prevalence of wear for children 12+ years old was 50% (PR = 0.5; 95% CI = 0.3–0.8) lower than that of children <12 years old. Angle’s class II was associated with higher tooth wear prevalence (PR = 1.8; 95% CI = 1.3–2.6) than class I. Children with posterior or anterior open bite had lower prevalence of wear than their counterparts (PR = 0.6; 95% CI = 0.3–1.0). No associations were observed between tooth wear and orthodontic treatment, missing teeth, and race/ethnicity. Conclusion: Tooth wear is a prevalent condition in this population. Among adults, higher prevalences of tooth wear were observed among those who were older, males, had used occlusal splints and had periodontal disease. Among children, higher prevalences were associated with younger age, male gender, class II malocclusion and the absence of open bite. Submitted on behalf of the Northwest PRECEDENT network, with support from NIDCR grants DE016750 and DE016752.     

上颌四眼簧扩弓纠正早期功能性下颌偏斜的髁突位置变化研究

目的:通过颞下颌关节断层片测量,探讨上颌四眼簧扩弓纠正单侧后牙反(牙合),改善早期功能性下颌偏斜后髁突位置的变化.方法:混合牙列或早期恒牙列,单侧后牙反(牙合)伴有或不伴有前牙反(牙合),下颌功能性偏斜患者16例,采用上颌Quad-Helix扩弓法,对矫治前后颞下颌关节断层片进行测量分析.结果:单侧后牙反(牙合)矫正后,偏斜侧T1期与T2期髁突位置变化无统计学意义(P＞0.05).对侧髁突向后移动,即治疗后,对侧关节腔前间隙增大,上间隙和后间隙比治疗前减小(p＜0.05).结论:混合牙列或早期恒牙列,上颌四眼簧扩弓器纠正单侧后牙反(牙合),使髁突与关节窝关系发生改变,两侧髁突运动逐渐对称.