Crown-root ratio of permanent teeth in cleft lip and palate patients

Objectives:To determine root lengths of fully developed permanent teeth of cleft lip and palate (CLP) patients and to define their crown-root (C/R) ratios.Method:Crown height and root length of permanent teeth were measured from panoramic radiographs of 44 CLP patients and 37 controls. A total of 1397 teeth were measured, and C/R ratios were calculated.Results:Higher C/R ratios were found in CLP patients; this was statistically significant for both maxillary and mandibular incisors and canines. Bilateral CLP subjects showed higher C/R ratios in general than unilateral CLP subjects. Roots of maxillary incisors, canines, and some other teeth were significantly shorter in CLP patients than in controls.Conclusions:CLP patients should be considered to have unfavorable C/R ratios, which could be the result of short root lengths for some teeth.     

Nonsurgical treatment of skeletal anterior open bite in adult patients: Posterior build-ups

Objective:To (1) evaluate the efficacy of build-ups in the correction of anterior open bite in adults, (2) evaluate their efficacy in producing molar intrusion, (3) analyze skeletal and dental changes, and (4) assess the long-term stability.Materials and Methods:The sample consisted of 93 lateral cephalograms from 31 patients with skeletal and dental anterior open bite. The patients had received orthodontic treatment consisting of bonded resin blocks on the maxillary molars combined with Tip-Edge Plus bracket appliances. Cephalometric measurements were performed on radiographs taken before treatment (T1), after treatment (T2), and after a retention period (T3), which were analyzed and compared.Results:Significant dental and skeletal changes were observed after treatment. Molar intrusion averaging 1 mm; 1.44 and 1.57 mm extrusion of mandibular and maxillary incisors, respectively; and a mean of 3.98 mm overbite increase were observed. The mandibular plane angle showed a mean closure of 1.19°, and there was a mean decrease in anterior facial height of 0.7 mm. A mild relapse tendency was observed, but long-term stability was acceptable.Conclusions:Build-ups are an effective treatment alternative for anterior open bite in adults. Outcomes remain significantly stable during the retention period.     

Cephalometric comparison of adult anterior open bite treatment using clear aligners and fixed appliances

Objectives:To compare fixed appliances and clear aligner therapy in correcting anterior open bite and in controlling the vertical dimension in adult patients with hyperdivergent skeletal patterns.Materials and Methods:In this retrospective study, two treatment groups of adult (≥18 years old) hyperdivergent patients (mandibular plane angles of ≥38°) with anterior open bites were included: 17 fixed appliance patients and 36 clear aligner patients. Thirteen cephalometric measurements representing the vertical dimension were reported for each group. A two-sample t-test was used to assess differences in changes in mandibular plane angle and overbite between the two treatment groups.Results:There were no statistical differences found in the magnitude of overbite correction and the changes in any of the cephalometric measurements for vertical control. The clear aligner group showed a slightly greater amount of lower incisor extrusion (P = .009). The main mechanism of open bite correction was similar between the two treatment groups and was accomplished through retroclination of the upper and lower incisors while maintaining the vertical position of the upper and lower molars.Conclusions:Cephalometric comparison of anterior open bite correction and changes in the mandibular plane angle associated with use of clear aligners and fixed appliances did not demonstrate statistically significant differences in adult hyperdivergent patients.     

Root-crown ratios of permanent teeth in a healthy Finnish population assessed from panoramic radiographs

An unfavourable root-crown (R/C) ratio caused by short dental roots may result from a developmental deficiency, root resorption after orthodontic treatment, or dental trauma. In the assessment of root shortening, subjective grading has often been used. For objective tooth measurements, varying materials and methods may make the results impossible to compare. This study used a simple, objective method to assess the R/C ratio (relative root length) of mature permanent teeth from panoramic radiographs (PRGs), tested its reproducibility and calculated the mean values of R/C ratios and their variations in a healthy Caucasian (Finnish) population. Two thousand seven hundred and seventy-nine teeth were measured on 108 PRGs. The intra- and inter-examiner reproducibility of the assessment method was good (Pearson correlation coefficients 0.87 and 0.83, respectively; P < 0.001) and the mean R/C ratios did not differ between the repeated measurements (P > 0.05). The biological variance in all cases exceeded the error variance for each tooth. These facts suggest that the method reported in this study can be used in the assessment of the relative root length of 'normal' teeth and its alterations in teeth with developmental or acquired aberrations of dental roots. Males, overall, tended to have higher R/C ratios than females; P-values varied from non-significant to less than 0.01. With the exception of the permanent lateral incisors in males and the permanent second molars in both genders, the ratios of the antagonist teeth were significantly greater in the mandible than in the maxilla (P < 0.05 for the lateral incisors of females; P < 0.001 for all other teeth). Consequently, in quantifying root shortening in developmentally short-rooted teeth, tooth- and gender-specific reference values should be employed. The Finnish R/C data reported here for all teeth except third molars could be used for comparison with other populations, patient groups or individuals where crown-root aberrations are suspected.     

Effects of palatal crib and bonded spurs in early treatment of anterior open bite: A prospective randomized clinical study

Objective:To evaluate the overbite correction of fixed palatal crib (FPC) and bonded lingual spur (BLS) in the early treatment of anterior open bite (AOB) in mixed dentition (primary outcome) as well as its influence on dental and skeletal cephalometric measurements (secondary outcome).Materials and Methods:The selected patients had AOB and a mean age of 8.23 years. They were divided into the following three groups by casting lots: control (n  =  13), palatal crib (n  =  13), and spur (n  =  13). Data from the lateral teleradiography was obtained at the beginning, at 6 months, and after 1 year. The cephalometric analysis was performed by Cef-X program, recording the values of SNA, SNB, ANB, SnG oGn, 1.PP, IMPA, nasolabial angle, overbite, and overjet. Intergroup and intragroup comparisons were obtained via one-way analysis of variance.Results:The degree of AOB was similar at baseline (P > .05). At 6 months and then after 1 year all groups showed improvement in the overbite. However, only the crib and spur groups showed positive overbite. No cephalometric measurements changed significantly over the period analyzed.Conclusions:We conclude that the FPC and BLS are simple and effective for the treatment of anterior open bite, with the advantage given to the FPC.     

Classification of Anterior Open Bite Using Individualized Cephalometry

OBJECTIVE: The objective of this study was to describe the cephalometric characteristics of the open bite, and to classify the open bite according to individualized norms. MATERIAL AND METHOD: The lateral cephalograms of 134 patients with an anterior open bite (min -0.5 mm) were analyzed. Patients were classified according to the inclination of the jaws, applying the principles of individualized cephalometry. The harmony box described by Hasund was used to define individualized norms for the inclination of the upper and lower jaws in each patient. The open bite was classified into four sub-types: (1) dental, (2) skeletal with enlarged ML-NSL angle, (3) skeletal with reduced ML-NSL angle, and (4) skeletal with deviations in upper and lower jaws. A skeletal open bite was found in 89 patients (66.4%). A dental open bite was found in 45 patients (33.6%). RESULTS: A number of significant differences were found between these four groups using single-factor variance analysis and the Bonferroni a posteriori test, (p < or = 0.05, p < or = 0.01, p < or = 0.001). The most prominent variables were index value of anterior facial hight, total facial height ratio, gonial angle, and Y-axis. No significant differences were found for overbite, however. CONCLUSION: It was possible to use individualized norms to classify the open bite into four sub-types. The demarcation between the four groups was supported statistically. The extent of the anterior open bite does not allow any conclusions as to the craniofacial pattern.     

单根牙牙槽骨吸收度与最大（牙合）力关系的研究

目的研究单根牙牙槽骨吸收程度与最大（牙合）力的关系.方法选择37例牙周病患者,710个单根牙,记录其前牙超覆（牙合）情况,拍摄牙片,测量每个受试牙的牙槽骨吸收程度和最大（牙合）力.结果最大牙合力值因个体间和牙位不同存在明显差异.当左右同名牙牙槽骨高度相近时,最大（牙合）力值相近.最大（牙合）力值与牙槽骨吸收程度有着明显的相关性,牙槽骨吸收程度增加,最大（牙合）力降低.牙周病易于导致前牙覆（牙合）深、超（牙合）大的（牙合）型.结论牙槽骨高度影响最大（牙合）力,牙周病将导致牙合的异常及咀嚼功能受到损害.     

Dimensional changes of dental arches produced by fixed and removable palatal cribs: A prospective,randomized, controlled study

Objective:To evaluate the dimensional changes of dental arches on digital models of open bite treatment with fixed and removable palatal cribs.Materials and Methods:The sample comprised 41 patients of both sexes who were white, aged 7–10 years, and who had mixed dentition, Angle Class I molar relationship, and a negative overbite of at least 1 mm. The sample was randomly divided into two groups: G1, fixed palatal crib; and G2, removable palatal crib. Cast models, obtained initially (T1) and after 1 year of treatment (T2), were scanned by a three-dimensional (3D) scanner, 3Shape R700, producing a 3D image. Measurements were performed by a calibrated examiner using OrthoAnalyzer™ 3D software.Results:At T2–T1, differences were observed between the groups regarding vertical dentoalveolar development and overjet. There was more mandibular incisor extrusion for G1 (−1.66 mm) than for G2 (−0.54 mm). An overjet increase was observed in G1 (0.56 mm), in contrast to a reduction in G2 (−0.40 mm). There was a similar overbite increase for both groups (3.51 mm for fixed palatal crib and 3.88 mm for removable palatal crib).Conclusions:Both the treatment protocols are similarly effective for anterior open bite correction, providing an overbite increase with dentoalveolar arch changes, especially in the anterior region.     

固定修复重建改善重度成人前牙深覆的研究

目的：总结重建改善成人重度深覆修复方法的综合应用和临床体会。方法：对9例重度前牙深覆伴不同程度牙体牙列缺损的患者,综合应用固定义齿修复,通过适度增高垂直距离的重建方式改善患者的咬合关系。结果：重建以后全部患者牙列形态良好,咬合稳定,咀嚼功能及前牙美观均得到明显改善,经过半年至1年观察,无患者出现颞下颌关节不适主诉。结论：在患者已存在牙体牙列缺损需要修复时,采取适当增加垂直高度的修复性重建方法,可在修复牙体牙列缺损的同时,有效改善成年重度前牙深覆患者的咬合关系、咀嚼功能和美观,是一种较理想的选择。     

Dentoalveolar compensation in Iranian adult skeletal open bite subjects

PurposeThe aim of present study was to compare skeletal and dentoalveolar features of compensated and noncompensated adult open bite subjects with each other and also with those of control group.Materials and methodsA total of 100 lateral cephalograms were included in the study and were divided according to skeletal vertical characteristics into two groups: control group (CG) and open bite group (OBG). The OBG further divided into two subgroups based on amount of overbite: dentally compensated open bite group (COBG) and non compensated open bite group (NCOBG). Twenty skeletal and dentoalveolar variables were evaluated and compared between OBG and CG and also between open bite subgroups by means of Student t-test. Association between different variables and overbite was assessed using Pearson's correlation coefficient.ResultsIncreased molar and incisor height in both jaws were observed in OBG compared to CG. In NCOBG lower anterior facial height and lower posterior dentoalveolar height were significantly higher than COBG.ConclusionDentoalveolar compensatory mechanisms in skeletal open bite patients consist of increased anterior and posterior dentoalveolar heights in upper and lower jaws compared to CG, while decreased mandibular molar height and shorter anterior face height are the most important determinants of adequate compensation in skeletal open bite subjects in our sample.     

Is mild dental invagination a risk factor for apical root resorption in orthodontic patients?

The purpose of this retrospective study was to assess if dental invagination is a risk factor for root resorption during orthodontic treatment. The sample consisted of 91 patients (32 males, 59 females) with a mean age of 13.1 years (range 9.3-32.1 years) with complete orthodontic records, including periapical radiographs of the maxillary incisors before and after treatment. Forty-nine patients had at least one maxillary incisor invaginated, whilst the remaining 42 patients were free of dental invaginations. Variables recorded for each patient included gender, age, Angle classification, extraction or non-extraction therapy, ANB angle, overjet, overbite, trauma, habits, agenesis, tooth exfoliation, treatment duration, Class II elastics, body-build, general factors, impacted canines, and root form deviation. Crown and root length of the maxillary incisors were measured on pre- and post-treatment long cone periapical radiographs corrected for image distortion. The percentage of root shortening and root length loss in millimetres was then calculated. Most of the invaginated teeth were minor type 1. Statistical analysis revealed no significant difference in the severity of apical root resorption between invaginated and non-invaginated incisors in patients without dental invaginations, nor was the extent of dental invagination related to the severity of apical root resorption. However, invaginated teeth had malformed roots more often than non-invaginated teeth. Dental invagination, and particularly type 1, cannot be considered a risk factor for apical root resorption during orthodontic tooth movement.     

三种预备方法对直根管根尖封闭性的影响

根管治疗术是治疗口腔常见疾病＂牙髓病和根尖周病＂的最根本和最有效的方法。本研究的目的是观察应用步退法[1]和冠向下法根管预备对直根管根尖封闭性的影响,以供临床参考。     

Growth hormone receptor gene is related to root length and tooth length in human teeth

Objectives:To examine the relationship between tooth length and growth hormone receptor (GHR) gene variants in a healthy Japanese population.Materials and Methods:The subjects consisted of 193 Japanese adults (69 men, 124 women), aged 13 to 56 years. Genomic DNA was extracted from saliva and genotyped GHR rs6184 and rs6180 variants using the Taqman genotyping. Computed tomography (CT) images were acquired using a dental cone-beam CT scanner and reconstructed using open-source OsiriX medical image processing software. The maxillary (upper; U) and mandibular (lower, L) central incisors (1), lateral incisors (2), canines (3), first premolars (4), second premolars (5), first molars (6), and second premolars (7) were evaluated. Teeth were assessed for crown height (CH), root length (RL), overall tooth length (C+R), and crown to root ratio (C/R). The relationships between GHR variants and CH, RL, C+R, and C/R were statistically examined.Results:The GHR variant rs6184 was associated with the root lengths and tooth length for the upper and lower lateral incisors and upper canines (U2 RL; U3 RL, C+R; L2 RL [P < .05]).Conclusions:The results indicate that the GHR rs6184 variant is associated with tooth length and ratio dimensions in a Japanese cohort. Further studies utilizing a larger sample size are needed to confirm this finding.     

Longitudinal study of cephalometric soft tissue profile traits between the ages of 6 and 18 years

Objective:To study the longitudinal changes in 19 soft tissue cephalometric traits (according to the Bergman cephalometric soft tissue facial analysis).Materials and Methods:Cephalograms and photographs of 40 subjects (20 male, 20 female, from the Burlington Growth Centre) that were obtained at ages 6, 9, 12, 14, 16, and 18 years were used. Subjects were orthodontically untreated whites and had Class I dentoskeletal relationships (ideal overjet and overbite). Images were obtained with the lips in a relaxed position or lightly touching.Results:Three groups of soft tissue traits were identified: (1) traits that increased in size with growth (nasal projection, lower face height, chin projection, chin-throat length, upper and lower lip thickness, upper lip length, and lower lip–chin length); (2) traits that decreased in size with growth (interlabial gap and mandibular sulcus contour [only in females]); and (3) traits that remained relatively constant during growth (facial profile angle, nasolabial angle, lower face percentage, chin-throat/lower face height percentage, lower face–throat angle, upper incisor exposure, maxillary sulcus contour, and upper and lower lip protrusion).Conclusion:Current findings identify areas of growth and change in individuals with Class I skeletal and dental relationships with ideal overjet and overbite and should be considered during treatment planning of orthodontic and orthognathic patients.     

A cephalometric comparison of black open-bite subjects and black normals

Orthodontic surveys of the adolescent and adult population of the United States have shown that the incidence of anterior open bite is three to four times higher in blacks than in whites. A cephalometric comparison of black subjects with and without an open bite was used to identify skeletal and dental differences between the two groups. Statistically significant differences were found in the vertical skeletal dimensions and incisor proclination. The open-bite group had a significantly longer anterior lower facial height and total facial height. The mandibular plane was rotated down relative to the cranial base and Frankfort plane and gonial angle was increased in the open-bite sample. There were small differences between the open bite and non-open-bite groups in the cranial base angle and the overbite depth indicator of Kim. No significant differences were found in the skeletal anteroposterior dimensions or dental vertical development. The vertical skeletal pattern and the greater degree of dental proclination differentiated black patients with an anterior open bite from those without.     

46例儿童矫治保存上颌前牙弓外牙的临床分析

目的 分析儿童上颌前牙弓外牙的临床特点,研究矫正治疗,探讨其矫治效果。方法 选择46例上颌前牙弓外牙的儿童患者,采用减数拔牙,使用方丝弓,直丝弓固定矫治,结合Ⅰ类、Ⅱ类牵引,方丝控根移动使12、22完全移至牙弓内,关闭牙弓间隙,调正上、下关系正中。治疗前、后经临床检查,X线头影测量分析,曲面断层片,头颅侧位片、以及治疗前后模型测量分析对照,评价治疗效果。结果 46例儿童固定矫治后,ANB角减小0.98°;UI/SN和UI/PP分别减小7.86°和9.82°;LI/MP减小了4.1°;UIA-PTV和UIE-PTV分别减小了2.73mm和5.12mm;LIE-PTV和LIA-PTV分别减小了3.38mm、1.31mm;UM-PTV和LM-PTV分别增加了3.56m和4.38,与矫治前相比,差异均在5%上,统计学显著,大部分在差异的P值小于1%。另外,患者面部左右对称,上、下牙弓排列整齐,磨牙中性关系,覆、覆盖关系正常。结论 儿童前牙弓外牙通过临床早期矫治或双期矫治可达到明显的临床效果。     

Force magnitude as a variable in maxillary buccal segment intrusion in adult patients with skeletal open bite:: A double-blind randomized clinical trial

ObjectivesTo compare the effects of two different force magnitudes on maxillary posterior segment intrusion using mini-screws. The null hypothesis was that there would be no difference between the two force magnitudes.Materials and MethodsAdult patients with skeletal open bite and a dental open bite ranging from 3 to 8 mm were recruited for this trial. The comparator group had 200 g of intrusive force applied for posterior segment intrusion, whereas 400 g of force was applied in the intervention group. Primary outcomes were the amount of posterior teeth intrusion and anterior open bite closure.ResultsTwenty-two subjects were randomized to include 11 participants in each group. One participant dropped out in each group, leaving us with 10 subjects to be analyzed per group. There was statistically significant posterior teeth intrusion of 2.42 ± 2.06 and 2.26 ± 1.87 mm for the comparator and intervention groups, respectively, with no difference between them. Statistically significant open bite closure was achieved in both groups, measuring 2.24 ± 1.18 and 3.15 ± 1.06 mm in the comparator and intervention groups, respectively, with no difference between them.ConclusionsBoth the 200 g and 400 g intrusive forces yielded similar outcomes in terms of posterior teeth intrusion and anterior open bite closure.     

Anterior open bite in the deciduous dentition: longitudinal follow-up and craniofacial growth considerations.

The aim of this longitudinal cephalometric study was to evaluate craniofacial growth changes in subjects with an anterior open bite in the deciduous dentition. From longitudinal records of untreated subjects, an open bite group (n = 14) was selected at the age of 5 years based on the presence of a negative overbite and compared with a control group (n = 14) with a regular overbite at this age. Cephalometric measurements were analyzed at ages 5, 9, and 12 years. Although only 1 subject in the deciduous dentition open bite group had an open bite at 12 years of age, the overbite remained lower during the longitudinal follow-up. Early cephalometric characteristics of the open bite group included a reduced overbite depth indicator and a lower ANB angle. At ages 9 and 12 years, the open bite sample was also characterized by shorter ramus height. An underlying skeletal pattern seems to be present in the deciduous dentition open bite sample that persists during the longitudinal follow-up. The overbite depth indicator might help to identify patients with anterior open bite tendencies.     

When should root remnants and unrestorable broken teeth be extracted in frail older adults?

BackgroundMany frail older adults have an unhealthy dentition; unrestorable broken teeth and root remnants with open root canals, commonly accompanied by periapical and periodontal inflammation, are often seen. Improving oral health in the growing group of frail older adults with remaining teeth is a considerable challenge for dental care professionals. Dentists are often uncertain how to deal with root remnants and unrestorable broken teeth in frail older adults.MethodsThe authors aim was to provide recommendations to dentists to help in their clinical decision making about the extraction or retention of roots remnants and broken teeth in frail older adults.ConclusionsDecisions about the extraction or retention of root remnants should made on the basis of preventing pain and oral discomfort, preventing severe inflammation, and preventing additional decline in oral health. Both root-related and patient-related factors are considered.Practical ImplicationsDecision-making trees can help dentists decide whether to extract root remnants and unrestorable broken teeth in frail older adults.     

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.