[Show abstract][Hide abstract] ABSTRACT: The objective of this study was to investigate whether multistranded fixed retainers prevented overeruption of unopposed mandibular second molars in maxillary first molar extraction cases.
The panoramic radiographs of 65 Class II Division 1 Caucasian Whites (28 females, 37 males) consecutively treated with bilateral maxillary first molar extraction and the Begg technique, and with records taken after treatment (T1) and in retention (T2), were withdrawn from private practice records. After appliance removal, mandibular second molars were retained with sectional wires till at least T2 in case of lack of occlusal contact with the antagonist. The subjects were assigned to study-retention and control-nonretention groups based on the retention status of mandibular second molars. Radiographic analysis was carried out to determine inclination of mandibular molars and the resulting movement of second molar centroids. Parametric and nonparametric tests were performed to assess the changes between T1 and T2.
No statistically significant differences in molar inclination were observed between groups and timepoints (P > 0.05). There were no statistically significant differences in molar movement percentages (P > 0.05) irrespective of whether fixed retention had been used or not.
No significant eruption occurred in unopposed mandibular second molars bonded with fixed sectional retainers compared to molars partially occluded with the antagonists without fixed retention. Given the study limitations, fixed retention should be considered with caution in restricting tooth overeruption in unopposed molars.
[Show abstract][Hide abstract] ABSTRACT: Background:
Bone dehiscences and gingival recession have been associated with orthodontic arch expansion. The aim of this study was to assess and compare periodontal modeling during application of two force levels.
The second and third upper molars were orthodontically moved buccally with conventional or low forces for 60 or 90 days in 32 rats. 10 non-treated animals were used as controls. The influence of force level and time on dental, skeletal, and periodontal parameters (i.e. height and thickness of gingiva and bone) was assessed on histomicrographs using a mixed linear model.
Facial tooth position (725μm, CI 379μm to 1072μm, distal root of the third molar) and maxillary skeletal width (295μm, CI 168μm to 421μm) differed significantly between force groups. Despite bone apposition at the facial aspects of the moved roots, bone dehiscences were developing and bone thickness was decreasing during facial tooth movement. Development of gingival recession was scarce and in cases with extreme facial tooth movement. No remarkable differences between force levels were found for any of the periodontal parameters.
Facial tooth movement with conventional or low forces resulted in similar modeling of facial alveolar bone and gingiva. This article is protected by copyright. All rights reserved.
No preview · Article · Jan 2016 · Journal Of Clinical Periodontology
[Show abstract][Hide abstract] ABSTRACT: In Pierre Robin sequence, a retracted tongue due to micrognathia is thought to physically obstruct palatal shelf elevation and thereby cause cleft palate. However, micrognathia is not always associated with palatal clefting. Here, by using the Bmp7-null mouse model presenting with cleft palate and severe micrognathia, we provide the first causative mechanism linking the two. In wild-type embryos, the genioglossus muscle, which mediates tongue protrusion, originates from the rostral process of Meckel's cartilage and later from the mandibular symphysis, with 2 tendons positive for Scleraxis messenger RNA. In E13.5 Bmp7-null embryos, a rostral process failed to form, and a mandibular symphysis was absent at E17.5. Consequently, the genioglossus muscle fibers were diverted toward the lingual surface of Meckel's cartilage and mandibles, where they attached in an aponeurosis that ectopically expressed Scleraxis. The deflection of genioglossus fibers from the anterior-posterior toward the medial-lateral axis alters their direction of contraction and necessarily compromises tongue protrusion. Since this muscle abnormality precedes palatal shelf elevation, it is likely to contribute to clefting. In contrast, embryos with a cranial mesenchyme-specific deletion of Bmp7 (Bmp7:Wnt1-Cre) exhibited some degree of micrognathia but no cleft palate. In these embryos, a rostral process was present, indicating that mesenchyme-derived Bmp7 is dispensable for its formation. Moreover, the genioglossus appeared normal in Bmp7:Wnt1-Cre embryos, further supporting a role of aberrant tongue muscle attachment in palatal clefting. We thus propose that in Pierre Robin sequence, palatal shelf elevation is not impaired simply by physical obstruction by the tongue but by a specific developmental defect that leads to functional changes in tongue movements.
No preview · Article · Dec 2015 · Journal of dental research
[Show abstract][Hide abstract] ABSTRACT: Objective:
Facial attractiveness is an important factor in our social interactions. It is still not entirely clear which factors influence the attractiveness of a face and facial asymmetry appears to play a certain role. The aim of the present study was to assess the association between facial attractiveness and regional facial asymmetries evaluated on three-dimensional (3D) images.
3D facial images of 59 (23 male, 36 female) young adult patients (age 16-25 years) before orthodontic treatment were evaluated for asymmetry. The same 3D images were presented to 12 lay judges who rated the attractiveness of each subject on a 100mm visual analogue scale. Reliability of the method was assessed with Bland-Altman plots and Cronbach's alpha coefficient.
All subjects showed a certain amount of asymmetry in all regions of the face; most asymmetry was found in the chin and cheek areas and less in the lip, nose and forehead areas. No statistically significant differences in regional facial asymmetries were found between male and female subjects (P > 0.05). Regression analyses demonstrated that the judgement of facial attractiveness was not influenced by absolute regional facial asymmetries when gender, facial width-to-height ratio and type of malocclusion were controlled (P > 0.05).
A potential limitation of the study could be that other biologic and cultural factors influencing the perception of facial attractiveness were not controlled for.
A small amount of asymmetry was present in all subjects assessed in this study, and asymmetry of this magnitude may not influence the assessment of facial attractiveness.
Full-text · Article · Dec 2015 · The European Journal of Orthodontics
[Show abstract][Hide abstract] ABSTRACT: Objective:
To determine whether judgment of nasolabial esthetics in cleft lip and palate (CLP) is influenced by overall facial attractiveness.
University of Bern, Switzerland.
Subjects and methods:
Seventy-two fused images (36 of boys, 36 of girls) were constructed. Each image comprised (1) the nasolabial region of a treated child with complete unilateral CLP (UCLP) and (2) the external facial features, i.e., the face with masked nasolabial region, of a noncleft child. Photographs of the nasolabial region of six boys and six girls with UCLP representing a wide range of esthetic outcomes, i.e., from very good to very poor appearance, were randomly chosen from a sample of 60 consecutively treated patients in whom nasolabial esthetics had been rated in a previous study. Photographs of external facial features of six boys and six girls without UCLP with various esthetics were randomly selected from patients' files. Eight lay raters evaluated the fused images using a 100-mm visual analogue scale. Method reliability was assessed by reevaluation of fused images after >1 month. A regression model was used to analyze which elements of facial esthetics influenced the perception of nasolabial appearance.
Method reliability was good. A regression analysis demonstrated that only the appearance of the nasolabial area affected the esthetic scores of fused images (coefficient = -11.44; P < .001; R(2) = 0.464). The appearance of the external facial features did not influence perceptions of fused images.
Cropping facial images for assessment of nasolabial appearance in CLP seems unnecessary. Instead, esthetic evaluation can be performed on images of full faces.
Full-text · Article · May 2015 · The Cleft Palate-Craniofacial Journal
[Show abstract][Hide abstract] ABSTRACT: To assess the maxillary second molar (M2) and third molar (M3) inclination following orthodontic treatment of Class II subdivision malocclusion with unilateral maxillary first molar (M1) extraction.
Panoramic radiographs of 21 Class II subdivision adolescents (eight boys, 13 girls; mean age, 12.8 years; standard deviation, 1.7 years) before treatment, after treatment with extraction of one maxillary first molar and Begg appliances and after at least 1.8 years in retention were retrospectively collected from a private practice. M2 and M3 inclination angles (M2/ITP, M2/IOP, M3/ITP, M3/IOP), constructed by intertuberosity (ITP) and interorbital planes (IOP), were calculated for the extracted and nonextracted segments. Random effects regression analysis was performed to evaluate the effect on the molar angulation of extraction, time, and gender after adjusting for baseline measurements.
Time and extraction status were significant predictors for M2 angulation. M2/ITP and M2/IOP decreased by 4.04 (95% confidence interval [CI]: -6.93, 1.16; P = .001) and 3.67 (95% CI: -6.76, -0.58; P = .020) in the extraction group compared to the nonextraction group after adjusting for time and gender. The adjusted analysis showed that extraction was the only predictor for M3 angulation that reached statistical significance. M3 mesial inclination increased by 7.38° (95% CI: -11.2, -3.54; P < .001) and 7.33° (95% CI: -11.48, -3.19; P = .001).
M2 and M3 uprighting significantly improved in the extraction side after orthodontic treatment with unilateral maxillary M1 extraction. There was a significant increase in mesial tipping of maxillary second molar crowns over time.
Full-text · Article · Mar 2015 · The Angle Orthodontist
[Show abstract][Hide abstract] ABSTRACT: To test the applicability, accuracy, precision, and reproducibility of various 3D superimposition techniques for radiographic data, transformed to triangulated surface data.
Five superimposition techniques (3P: three-point registration; AC: anterior cranial base; AC + F: anterior cranial base + foramen magnum; BZ: both zygomatic arches; 1Z: one zygomatic arch) were tested using eight pairs of pre-existing CT data (pre- and post-treatment). These were obtained from non-growing orthodontic patients treated with rapid maxillary expansion. All datasets were superimposed by three operators independently, who repeated the whole procedure one month later. Accuracy was assessed by the distance (D) between superimposed datasets on three form-stable anatomical areas, located on the anterior cranial base and the foramen magnum. Precision and reproducibility were assessed using the distances between models at four specific landmarks. Non parametric multivariate models and Bland-Altman difference plots were used for analyses.
There was no difference among operators or between time points on the accuracy of each superimposition technique (p>0.05). The AC + F technique was the most accurate (D<0.17 mm), as expected, followed by AC and BZ superimpositions that presented similar level of accuracy (D<0.5 mm). 3P and 1Z were the least accurate superimpositions (0.79<D<1.76 mm, p<0.005). Although there was no difference among operators or between time points on the precision of each superimposition technique (p>0.05), the detected structural changes differed significantly between different techniques (p<0.05). Bland-Altman difference plots showed that BZ superimposition was comparable to AC, though it presented slightly higher random error.
Superimposition of 3D datasets using surface models created from voxel data can provide accurate, precise, and reproducible results, offering also high efficiency and increased post-processing capabilities. In the present study population, the BZ superimposition was comparable to AC, with the added advantage of being applicable to scans with a smaller field of view.
[Show abstract][Hide abstract] ABSTRACT: Objective:
To examine the supporting evidence of advertisements published in six leading orthodontic journals.
Materials and methods:
The 2012-2013 printed issues of American Journal of Orthodontics and Dentofacial Orthopedics, Australian Orthodontic Journal, Journal of Orthodontics, European Journal of Orthodontics, Journal of Clinical Orthodontics, and Journal of Orofacial Orthopedics were screened for advertisements implying superior performance compared with competitor products. Advertisements were classified according to type of product, availability, and currency of supporting references.
A total of 99 unique advertisements claiming clinical benefit or superiority were identified. The overwhelming majority of the identified advertisements promoted appliance products (62.6%), orthodontic materials (14.1%), and dental operatory equipment, including imaging systems (12.1%). Advertisements were found to provide references or not regardless of the product type. Half of the advertisements referred to at least one peer-reviewed publication, whereas unpublished studies were cited by 25% of the advertisements. Most of the referenced articles were published within the past 5 years.
The scientific background of advertisements in the orthodontic literature appears limited. While surveillance of journal advertising needs to be regulated, clinicians are urged to critically appraise the claims being made in orthodontic print advertisements by consulting the associated existing evidence.
Full-text · Article · Dec 2014 · The Angle Orthodontist
[Show abstract][Hide abstract] ABSTRACT: Cone-Beam Computed Tomography (CBCT) has been introduced in 1998. This radiological imaging procedure has been provided for dentistry and is comparable to computed tomography (CT) in medicine. It is expected that CBCT will have the same success in dental diagnostic imaging as computed tomography had in medicine. Just as CT is responsible for a significant rise in radiation dose to the population from medical X-ray diagnostics, CBCT studies will be accompanied by a significant increase of the dose to our patients by dentistry. Because of the growing concern for an uncritical and consequently rapidly increasing use of CBCT the Swiss Society of Dentomaxillofacial Radiology convened a first consensus conference in 2011 to formulate indications for CBCT, which can be used as guidelines. In this meeting, oral and maxillofacial surgery, orthodontics and temporomandibular joint disorders and diseases were treated and the most important and most experienced users of DVT in these areas were asked to participate. In general, a highly restrictive use of CBCT is re- quired. Justifying main criterion for CBCT applica- tion is that additional, therapy-relevant informa- tion is expected that should lead to a significant benefit in patient care. All users of CBCT should have completed a structured, high-level training, just like that offered by the Swiss Society of Den- tomaxillofacial Radiology.
Full-text · Article · Nov 2014 · Swiss Dental Journal
[Show abstract][Hide abstract] ABSTRACT: Objective:
To evaluate the long-term effects of asymmetrical maxillary first molar (M1) extraction in Class II subdivision treatment.
Materials and methods:
Records of 20 Class II subdivision whites (7 boys, 13 girls; mean age, 13.0 years; SD, 1.7 years) consecutively treated with the Begg technique and M1 extraction, and 15 untreated asymmetrical Class II adolescents (4 boys, 11 girls; mean age, 12.2 years; SD, 1.3 years) were examined in this study. Cephalometric analysis and PAR assessment were carried out before treatment (T1), after treatment (T2), and on average 2.5 years posttreatment (T3) for the treatment group, and at similar time points and average follow-up of 1.8 years for the controls.
The adjusted analysis indicated that the maxillary incisors were 2.3 mm more retracted in relation to A-Pog between T1 and T3 (β = 2.31; 95% CI; 0.76, 3.87), whereas the mandibular incisors were 1.3 mm more protracted (β = 1.34; 95% CI; 0.09, 2.59), and 5.9° more proclined to the mandibular plane (β = 5.92; 95% CI; 1.43, 10.41) compared with controls. The lower lip appeared 1.4 mm more protrusive relative to the subnasale-soft tissue-Pog line throughout the observation period in the treated adolescents (β = 1.43; 95% CI; 0.18, 2.67). There was a significant PAR score reduction over the entire follow-up period in the molar extraction group (β = -6.73; 95% CI; -10.7, -2.7). At T2, 65% of the subjects had maxillary midlines perfectly aligned with the face.
Unilateral M1 extraction in asymmetrical Class II cases may lead to favorable occlusal outcomes in the long term without harming the midline esthetics and soft tissue profile.
Full-text · Article · Nov 2014 · The Angle Orthodontist
[Show abstract][Hide abstract] ABSTRACT: In a fraction of patients surgically treated for cleft lip/palate, excessive scarring disturbs maxillary growth and dento-alveolar development. Since certain genes are involved in craniofacial morphogenesis as well as tissue repair, a primary defect causing cleft lip/palate could lead to altered wound healing. We performed in vitro wound healing assays with primary lip fibroblasts from 16 cleft lip/palate patients. Nine foreskin fibroblast strains were included for comparison. Cells were grown to confluency and scratch wounds were applied; wound closure was monitored morphometrically over time. Wound closure rate showed highly significant differences between fibroblast strains. Statistically, fibroblast strains from the 25 individuals could be divided into three migratory groups, namely "fast", "intermediate", and "slow". Most cleft lip/palate fibroblasts were distributed between the "fast" (5 strains) and the "intermediate" group (10 strains). These phenotypes were stable over different cell passages from the same individual. Expression of genes involved in cleft lip/palate and wound repair was determined by quantitative PCR. Transforming growth factor-α mRNA was significantly up-regulated in the "fast" group. 5 ng/ml transforming growth factor-α added to the culture medium increased the wound closure rate of cleft lip/palate strains from the "intermediate" migratory group to the level of the "fast", but had no effect on the latter group. Conversely, antibody to transforming growth factor-α or a specific inhibitor of its receptor most effectively reduced the wound closure rate of "fast" cleft lip/palate strains. Thus, fibroblasts from a distinct subgroup of cleft lip/palate patients exhibit an increased migration rate into wounds in vitro, which is linked to higher transforming growth factor-α expression and attenuated by interfering with its signaling.