Effects of the degree of overbite and overjet on dental health

The purpose of the study was to examine whether any combination of vertical overbite (OB) and horizontal overjet (OJ) may be more favourable than others to dental health in anterior segments. The study group consisted of 74 females and 70 males. The participants were 15-years-old and had 6 anterior teeth in both jaws. The following parameters were assessed: plaque index, gingival index, probing depth, space index, filled surfaces, the number of non-aligned proximal tooth surfaces (NONAS) and the OB/OJ ratio. The results demonstrated that participants with a relatively high OB/OJ ratio (OB/OJ greater than or equal to 1.21) had a more favourable periodontal condition than participants with lower ratios. This was so in both sexes and both jaws. The OB/OJ ratio had little relation to the prevalence of filled surfaces.     

Relationships between the upper central incisor crown forms and degree of labial inclination,overbite, and overjet in Japanese young adults

PURPOSEThe present study aimed to investigate the relationships between the crown form of the upper central incisor and their labial inclination, overbite, and overjet.MATERIALS AND METHODSMaxillary and mandibular casts of 169 healthy dentitions were subjected to 3D dental scanning, and analyzed using CAD software. The crown forms were divided into tapered, square, and ovoid based on the mesiodistal dimensions at 20% of the crown height to that at 40%. The degree of labial inclination of the upper central incisor was defined as the angle between the occlusal plane and the line connecting the incisal edge and tooth cervix. The incisal edges of the right upper and lower central incisor that in contact with lines parallel to the occlusal plane were used to determine the overbite and overjet. One-way ANOVA was performed to compare the labial inclination, overbite, and overjet among the crown forms.RESULTSThe crown forms were classified into three types; crown forms with a 20%/40% dimension ratio of 1.00±0.01 were defined as square, >1.01 as tapered, and <0.99 as ovoid. The labial inclination degree was the greatest in tapered and the least in square. Both overbite and overjet in tapered and ovoid were higher than those in square.CONCLUSIONUpper central incisor crown forms were related to their labial inclination, overbite, and overjet. It was suggested that the labial inclination, overbite, and overjet should be taken into consideration for the prosthetic treatment or restoring the front teeth crowns.     

成人前牙深覆(牙合)深覆盖的正畸修复联合治疗

目的：探讨正畸联合烤瓷固定修复治疗成人前牙深覆耠深覆盖的临床效果。方法：对前牙深覆[牙合]深覆盖成人患者,采用固定矫治技术整平下颌牙弓,解除深覆[牙合],为上前牙内收获得有效间隙后,行上前牙的改向烤瓷固定修复。结果：治疗后上前牙平均内收5.0mm,下颌spee氏曲线降低1.5mm-2.0mm,患者的面部侧貌得到改善,牙列形态与咬合恢复满意,咀嚼功能良好,随访6～20个月无复发。结论：对前牙深覆[牙合]深覆盖的成人患者采用正畸：联合固定修复进行治疗,既可有效的改善患者的咀嚼功能与美观,又可使下颌牙的牙体组织得以保存,达到更好的口腔修复效果。     

The nasopharynx, face height, and overbite

In lateral cephalometric films of a group of male subjects, none of whom was a mouth breather, the statistical relationships between overbite and nasopharyngeal dimensions were weak. Moderate relationships were found between face height and nasopharyngeal dimensions. Strongest correlations, with a peak at 10 years, were between--Face height and nasopharyngeal height (+) Face height and nasopharyngeal area (+) Face height and roof angle (-) Dynamic correlations between overbite, face height and nasopharyngeal dimensions were weak. Class II malocclusion subjects on average showed--Smaller Nasopharyngeal and Adenoid Areas. Larger Airways in both real and proportional terms, compared with Class I and normal occlusion subjects.     

Severe dental open bite malocclusion with tongue reduction after orthodontic treatment.

We treated a 21-year-old woman with a severe open bite and macroglossia with a standard edgewise appliance and without partial glossectomy. This was followed by retention using a Begg-type plate retainer for the upper dental arch and a fixed canine-to-canine for the lower arch. A crib was added to the upper plate retainer for suppression of a tongue thrust. The lower arch relapsed during the retention period, with a widening of the intermolar distance, flaring of the anterior teeth, and increased mobility of the teeth. We chose tongue reduction to resolve these problems and one-third of the middle dorsal part of the tongue was excised. After the tongue reduction, the patient experienced no functional problem in mastication, swallowing, and gustation, but she complained of mild speech difficulty and slight pain on the dorsal portion of her tongue. These symptoms disappeared 6 months after surgery. At this time, the mandibular dental arch was markedly improved. The flared lower dental arch had returned to an upright position and the tooth mobility reduced to normal. No appliance was used after surgery. Most of the recovery changes occurred within 4 months. This case highlights the importance of the teeth tending to move toward a balance between the tongue pressure from the inside and labio-buccal pressure from the outside.     

深覆盖患者治疗后2年以上的变化及其影响因素的分析

目的探讨深覆盖患者在保持阶段覆盖的变化及其相关影响因素。方法 本研究从北京大学口腔医学院正畸科搜集1990年-1998年间结束正畸治疗,且治疗前后资料完整(包括模型和头颅侧位片)、治疗前为深覆盖的患者49名,其中男性20名,女性29名;Ⅰ类患者20名,Ⅱ类患者29名,平均年龄为13.3岁。采用计算机头影测量及数显游标卡尺分别对治疗前后及随访时的头颅侧位片及牙(牙合)模型进行测量。结果随访时覆盖虽有一定程度的回复,但覆盖的复发量仅占矫正量的27％。覆盖的变化表现出明显的个体差异。下颌在矢状向上的生长有利于覆盖的稳定。上下切牙牙轴及矢状向位置的变化与覆盖的复发有关。     

Clinical crown height (length) – a review of published measurements

BACKGROUND, AIMS: Clinical crown height is an objective measure of the position of the gingival margin which could be used in determining the 'normal' position of the gingival margin. The aim of this study was to do a systematic review of published clinical crown heights in the human permanent dentition to compare the measurements and to see if a clear trend with age exists. MATERIAL AND METHODS: An on-line literature search was done using the key words clinical crown height (or) clinical crown length. From January 1975 to August 2000, 11 published papers have listed measurements; three of these report on all tooth types, the remainder on anterior teeth. RESULTS: All studies used the same measuring technique but age group reporting differed as did the tooth types measured. Measurements from the 10 acceptable studies of the clinical crown height of the same teeth are comparable at similar ages, so published values are reasonable estimates of 'normality' for diagnosis. There is a statistically significant increase in clinical crown height of central and lateral incisors with age that slows as age increases.     

Quantitative description of overjet and overbite and their relationship with the craniofacial morphology

This study was designed to explore whether overjet and overbite relationships might be correlated with the anteroposterior and vertical craniofacial dimensions. The material used to test this hypothesis was lateral cephalometric radiographs from 92 adults (49 women and 43 men) with Angle Class I molar and canine relationships and a harmonious profile. Data were analyzed using the t-test, Kendall's tau-b correlation and cluster analysis. The results revealed that a) women exhibit an increased overjet compared to men, and smaller vertical facial dimensions; b) there is a significant correlation between overjet and overbite, overbite and posterior facial height, and overbite and mandibular angle; c) in the two groups of individuals that were separated on the basis of overjet and overbite, only the mandibular plane exhibited a statistical difference between the two groups: groups with small values for overjet and overbite possess high mandibular angles and a decreased mandibular plane angle accompanies large values for overjet and overbite; d) groups separated on the basis of mandibular plane angle were not independent from the groups separated on the basis of overjet and overbite. In summary, occlusal characteristics are not found to be associated with any particular skeletal pattern.     

Quantitative description of overjet and overbite and their relationship with the craniofacial morphology.

OBJECTIVES: 1) To define the sagittal and vertical characteristics of anterior teeth in adults with normal occlusions; 2) to explore a relationship between the overbite and overjet; and 3) to relate overbite and overjet to the skeletal pattern. DESIGN: Prospective data collection. SETTING AND SAMPLE POPULATION: Ninety-two adult dental students from the Aristotle University of Thessaloniki (49 females and 43 males) with naturally occurring Class I occlusions. EXPERIMENTAL VARIABLE AND OUTCOME MEASURES: Cephalometric data were collected for overbite, overjet, and skeletal relationships. These were then correlated for potential association between front teeth and vertical and horizontal skeletal relationships. RESULTS: The overjet measures were equally distributed among men and women, but overbite was higher in women. Facial proportions were also bigger in men, but the Mediterranean face was bigger than Northern American Caucasian. The mandibular plane angle could be associated with either increased or decreased overjet and overbite. CONCLUSION: The overbite and overjet features of an occlusion cannot be predictably associated with any particular craniofacial pattern.     

Longitudinal cephalometric changes in incisor position,overjet, and overbite between 10 and 14 years of age

The purpose of this study was to evaluate the longitudinal growth changes in the incisor position, overjet, and overbite between 10 and 14 years of age. Serial cephalometric radiographs of 63 subjects (31 boys and 32 girls) were taken at the ages of 10, 11, 12, and 14. The effects of age and gender on the incisor positions, overjet, and overbite were investigated by means of variance analysis and least square difference (LSD) tests. The results show that the measurements of overbite, upper incisor-NA (mm), lower incisor-NB (mm), upper incisor-NA (angle), and the interincisal angle were affected by age. The results also show that the measurements of overbite, upper incisor-NA (mm), upper incisor-NA (angle) and upper incisor-SN (angle) were affected by gender.     

Age dependence of compliance with orthodontic treatment in children with large overjet. An interview study

Large overjet has been associated with an increased risk of trauma of the permanent maxillary incisors, especially before 10 years of age. The prevalence of an overjet of more than 6 mm in 10-year-old Swedish children is about 15%. To prevent trauma by reducing the overjet, this treatment be set in early in life. However, compliance with orthodontic treatment is a significant and well known problem and may be associated with the age of the patient. This study concerns children treated with an open activator with built in headgear (HG activator). The aim of treatment was to reduce the trauma risk in these patients as early as possible, and an objective of the study was to gain better knowledge of young children's (6-13 years of age) motivation for and response to correction of large overjet. In-depth interviews focusing on motivation were held with 18 children. Interviews were transcribed verbatim and analysed according to Grounded Theory, a qualitative method. The results indicate the importance of parental involvement for younger children's compliance. Older children seem to have a higher degree of internal motivation for treatment and less need for parental support for compliance with treatment. If treatment compliance can not be ensured through parents' wholehearted involvement and control it seems to be better to delay treatment until the child is older.     

上前牙缺失伴深覆(牙合)的修复前正畸

上前牙位于面部突出位置,常因外伤而缺失,当前牙深覆[牙合]时,上下牙之间的颌间隙过小,甚至下牙的切缘咬在上颌牙槽嵴的黏膜卜,没有足够的修复空间,如果勉强去修复,不但影响美观,还会影响牙颌系统的正常功能,有些甚至成为不良修复体,给患造成痛苦。我们用小平导,首先矫治深覆[牙合],取得足够的修复空间后,再进行修复治疗,取得了良好的临床效果。     

Nonsurgical orthodontic treatment of a hypodivergent adult patient with bilateral posterior scissors bite and excessive overjet

This report illustrates successful nonsurgical orthodontic treatment of a hypodivergent adult patient with bilateral posterior scissors bite (Brodie bite) and excessive overjet. A 26-year-old woman primarily reported maxillary incisor protrusion. She was diagnosed with Class ll division 1 malocclusion with skeletal Class I, short face, low mandibular plane angle and bilateral posterior scissors bite. A lingual arch with anterior bite block and posterior miniscrews with preadjusted edgewise appliances were used to improve the bilateral scissors bite. After achieving molar occlusion, the maxillary first premolars were extracted, and six miniscrews were used to improve the anterior-posterior and vertical discrepancies. After active treatment for 56 months, the convex facial profile with excessively protruded lips was improved and good interdigitation with ideal incisor relationship was achieved. Additionally, the irregular movements of the incisal path and the bilateral condyles during lateral excursion were improved. At 13 months of retention, a satisfactory facial profile, occlusion, and jaw movements were maintained. The treatment results suggest that miniscrews and fixed bite blocks were effective and efficient to facilitate correction of the bilateral scissors bite, excessive overjet, and vertical relationship correction in this nonsurgical orthodontic treatment.