Rostral and caudal pharyngeal arches share a common neural crest ground pattern

In vertebrates, face and throat structures, such as jaw, hyoid and thyroid cartilages develop from a rostrocaudal metameric series of pharyngeal arches, colonized by cranial neural crest cells (NCCs). Colinear Hox gene expression patterns underlie arch specific morphologies, with the exception of the first (mandibular) arch, which is devoid of any Hox gene activity. We have previously shown that the first and second (hyoid) arches share a common, Hox-free, patterning program. However, whether or not more posterior pharyngeal arch neural crest derivatives are also patterned on the top of the same ground-state remained an unanswered question. Here, we show that the simultaneous inactivation of all Hoxa cluster genes in NCCs leads to multiple jaw and first arch-like structures, partially replacing second, third and fourth arch derivatives, suggesting that rostral and caudal arches share the same mandibular arch-like ground patterning program. The additional inactivation of the Hoxd cluster did not significantly enhance such a homeotic phenotype, thus indicating a preponderant role of Hoxa genes in patterning skeletogenic NCCs. Moreover, we found that Hoxa2 and Hoxa3 act synergistically to pattern third and fourth arch derivatives. These results provide insights into how facial and throat structures are assembled during development, and have implications for the evolution of the pharyngeal region of the vertebrate head.

Cell lineage of primary and secondary enamel knots

Recent research indicates that control of cusp morphology involves a signalling center at the heart of the developing tooth germ, known as the enamel knot. The primary enamel knot forms in both incisors and molar tooth germs at the cap stage of tooth development. Secondary and tertiary enamel knots only develop in molar tooth germs. These sit at the sites of future cusp tips from the early bell stage of tooth development. In studies describing the relationship between the primary and secondary enamel knots, it is often assumed that there is a cellular continuity between these structures, such that cells from the primary enamel knot physically contribute to the secondary enamel knots. We have devised a method whereby the developing tooth germ can be cultured in frontal slices with the enamel knot visible. The fate of the primary enamel knot cells can then be followed by 1,1', di-octadecyl-3,3,3',3',-tetramethylindo-carbocyanine perchlorate (DiI) labeling. Using this method, no cells of the primary enamel knot were seen to move toward the developing secondary enamel knots. Thus, although the primary and secondary enamel knots have a close molecular and functional relationship in molar development, they are not actually derived from the same cells.

Genomewide scan for nonsyndromic cleft lip and palate in multigenerational Indian families reveals significant evidence of linkage at 13q33.1-34

Nonsyndromic cleft lip with or without cleft palate (CL-P) is a common congenital anomaly with incidence ranging from 1 in 300 to 1 in 2,500 live births. We analyzed two Indian pedigrees (UR017 and UR019) with isolated, nonsyndromic CL-P, in which the anomaly segregates as an autosomal dominant trait. The phenotype was variable, ranging from unilateral to bilateral CL-P. A genomewide linkage scan that used approximately 10,000 SNPs was performed. Nonparametric linkage (NPL) analysis identified 11 genomic regions (NPL>3.5; P<.005) that could potentially harbor CL-P susceptibility variations. Among those, the most significant evidence was for chromosome 13q33.1-34 at marker rs1830756 (NPL=5.57; P=.00024). This was also supported by parametric linkage; MOD score (LOD scores maximized over genetic model parameters) analysis favored an autosomal dominant model. The maximum LOD score was 4.45, and heterogeneity LOD was 4.45 (alpha =100%). Haplotype analysis with informative crossovers enabled the mapping of the CL-P locus to a region of approximately 20.17 cM (7.42 Mb) between SNPs rs951095 and rs726455. Thus, we have identified a novel genomic region on 13q33.1-34 that harbors a high-risk variant for CL-P in these Indian families.

Preoperative Cleft Lip Measurements and Maxillary Growth in Patients with Unilateral Cleft Lip and Palate

Objective

Maxillary growth in patients with cleft lip and palate is highly variable. The authors' aim was to investigate associations between preoperative cleft lip measurements and maxillary growth determined cephalometrically in patients with complete unilateral cleft lip and palate (cUCLP).

Design

Retrospective cross-sectional study.

Patients

Children with cUCLP.

Methods

Preoperative cleft lip measurements were made at the time of primary cheiloplasty and available for each patient. Maxillary growth was evaluated on lateral cephalometric radiographs taken prior to any orthodontic treatment and alveolar bone grafting (8.5 ± 0.7 years). The presence of associations between preoperative cleft lip measurements and cephalometric measures of maxillary growth was determined using regression analyses.

Results

In the 58 patients included in the study, the cleft lateral lip element was deficient in height in 90% and in transverse width in 81% of patients. There was an inverse correlation between cleft lateral lip height and transverse width with a β coefficient of −0.382 ( P = .003). Patients with a more deficient cleft lateral lip height displayed a shorter maxillary length (β coefficient = 0.336; P = .010), a less protruded maxilla (β coefficient = .334; P =.008), and a shorter anterior maxillary height (β coefficient = 0.306; P = .020) than those with a less deficient cleft lateral lip height.

Conclusions

Patients with cUCLP present with varying degrees of lateral lip hypoplasia. Preoperative measures of lateral lip deficiency are related to later observed deficiencies of maxillary length, protrusion, and height.

Masseter muscle thickness as a predictive variable in treatment outcome of the twin-block appliance and masseteric thickness changes during treatment

OBJECTIVES

To estimate the association of initial masseter muscle thickness with treatment outcomes using functional appliances and the effect of treatment on masseter muscle thickness.

MATERIAL AND METHODS

Twenty-two children, aged 8-12, with skeletal and dental class II relationships and increased overjet were treated with twin-block appliances for 9-17 months, until a class I molar relationship and decreased overjet was achieved. Dental casts, lateral cephalograms, and ultrasonographic measurements of the masseter muscle were performed before and after treatment. Twenty-two children, aged 8-12, without immediate need for orthodontic treatment, served as controls. They were observed for 11-17 months, and ultrasonographic masseter muscle measurements were taken before and after the observation period.

RESULTS

Masseter muscles in treated children were thinner at the end of treatment, while untreated controls showed an increase in thickness. Treated children with thinner pre-treatment muscles showed greater mandibular incisor proclination, distalisation of maxillary molars, and posterior displacement of the cephalometric A point during treatment.

CONCLUSION

Treatment of a dental class II relationship with functional appliances leads to mild atrophy of the masticatory muscles, possibly because of their decreased functional activity. The initial condition of the muscles may be associated with mandibular incisor proclination, and the position of maxillary first molars and A point.

Agenesis of maxillary lateral incisor and tooth replacement: cost-effectiveness of different treatment alternatives

PURPOSE

To evaluate the long-term cost-effectiveness of five treatment alternatives for maxillary lateral incisor agenesis where space maintenance and tooth replacement are indicated.

MATERIALS AND METHODS

The following treatment modalities were considered: single-tooth implant-supported crown, resin-bonded fixed partial denture (FPD), cantilever FPD, full-coverage FPD, and autotransplantation. The cost-effectiveness for each treatment modality was determined as the ratio of the outcome of each modality divided by the cost. Direct costs, clinical and laboratory, were calculated based on national fee schedules and converted to international dollars using purchasing power parity exchange rates. Outcomes were based on the most recently published long-term (10-year) survival rates. Sensitivity analyses were carried out, testing the robustness of the cost-effectiveness analysis.

RESULTS

The five treatment modalities ranked in the following order from most to least cost-effective: autotransplantation, cantilever FPDs, resin-bonded FPDs, single-tooth implants and implant-supported crowns, and full-coverage FPDs. Sensitivity analysis illustrated that the cost-effectiveness analysis was reliable in identifying autotransplantation as the most and full-coverage FPDs as the least cost-effective treatment modalities.

CONCLUSIONS

When replacing a missing maxillary lateral incisor, the most costeffective, long-term treatment modality is autotransplantation, whereas the least cost-effective is full-coverage FPDs. However, factors such as patient age, the state of the dentition, occlusion, and tooth conservation should also influence the choice of restoration.

The Need for Orthognathic Surgery in Nonsyndromic Patients with Repaired Isolated Cleft Palate

Objective

To determine the frequency of need for orthognathic surgery among nonsyndromic patients with isolated cleft palate repaired during infancy at The Hospital for Sick Children in Toronto, Canada.

Design

Retrospective cohort study.

Patients

Patients with nonsyndromic isolated cleft palate born between 1970 and 1997 with available records including a lateral cephalometric radiograph taken at 15 years of age.

Methods

Patients who had undergone or were being prepared for orthognathic surgery were automatically counted as requiring surgery. For the remaining patients, lateral cephalometric radiographs were traced and analyzed. Arbitrarily set cephalometric criteria were used to identify the “objective” need for orthognathic surgery.

Results

Of the 189 patients identified with nonsyndromic isolated cleft palate and for whom records were available, 25 (13.2%) were deemed to require orthognathic surgery. Of the surgical cohort, 92% required surgical correction for a Class III malocclusion. Similar percentages of males and females required orthognathic surgery. An apparently greater proportion of patients of Asian background (18.5%) than of white background (10.6%) required surgery, but this difference was not significant ( P = .205).

Conclusions

The current results suggest that approximately one in eight patients at our institution with nonsyndromic isolated cleft palate requires orthognathic surgery. There is a tendency for this to be higher in patients of Asian descent and lower in patients of white descent. Variability in extent, severity, and phenotype of the cleft, which may be attributed largely to genetics, may play an important role in dictating the need for orthognathic surgery.

Is Linear Advancement Related to Relapse in Unilateral Cleft Lip and Palate Orthognathic Surgery?

Objective

To investigate the stability of major versus minor Le Fort I maxillary advancements in unilateral cleft lip and palate (UCLP) patients.

Design

A retrospective longitudinal study was undertaken on 30 nonsyndromic UCLP patients treated with the same protocol at The Hospital for Sick Children, Toronto, Canada. Patients were grouped into major and minor movement groups based on planned surgical advancement. Standard lateral cephalometric radiographs were taken preoperatively (T1), immediately postoperatively (T2), and at least 1 year postoperatively (T3). Skeletal and dental variables were measured using cephalometric analysis. Stability was compared between groups using repeated-measures analysis of variance. Linear regression analysis was used to assess the relationship between advancement and relapse for the entire study population.

Results

A mean maxillary advancement of 9.8 mm and 4.9 mm was seen for the major (n = 10) and minor (n = 20) movement groups, respectively. The mean skeletal horizontal relapse was 1.8 mm (18%) for the major advancement group and 1.5 mm (31%) for the minor advancement group. There was no significant difference in skeletal horizontal relapse between the groups ( P > .05). The correlation coefficient ( r) between linear horizontal advancement and relapse was calculated to be .31 ( P > .05). Dental horizontal relapse was not significant for either the major or minor groups, and no significant difference was found between the groups ( P > .05)

Conclusion

Skeletal and dental relapse was found to be unrelated to the amount of maxillary linear advancement using conventional Le Fort I osteotomies in UCLP.

Mesiodistal tooth size in non-syndromic unilateral cleft lip and palate patients: a meta-analysis

OBJECTIVES

To evaluate, using meta-analysis methodology, mesiodistal tooth dimensions in non-syndromic unilateral cleft lip and palate (CLP) patients.

MATERIALS AND METHODS

A literature search was conducted using PubMed, Medline, Google Scholar Beta, EMBASE Excerpta Medica, CINAHL, Web of Science, and the Cochrane Collaboration, identifying English and non-English articles reporting on mesiodistal tooth dimensions on the cleft and non-cleft side of non-syndromic unilateral CLP patients. Additional studies were identified by searching reference lists of articles consulted. Only studies with a suitable control group were included. Two examiners independently performed the literature search and data extraction. Using meta-analysis software, data extracted from each selected study were statistically combined using the fixed-effects model. Weighted mean differences, 95 % confidence intervals, and heterogeneity were calculated for each measurement.

RESULTS

Four articles fulfilling the inclusion criteria were located and included in the meta-analysis. Maxillary incisors and first molars were found to be significantly larger on the non-cleft side while mandibular incisors and premolars were larger on the cleft side, in non-syndromic unilateral CLP patients. On the cleft side, maxillary premolars and second molars were larger in cleft than control patients while incisors were smaller, whereas all mandibular teeth were larger in cleft patients. On the non-cleft side, all maxillary teeth except for the central incisors were larger in the cleft than control patients, while all mandibular teeth were larger in the cleft patients except for lateral incisors.

CONCLUSIONS

Non-syndromic unilateral CLP patients tend to have larger posterior but smaller anterior teeth compared with the general population. Comparing sides, unilateral CLP patients tend to have smaller maxillary but larger mandibular teeth on the cleft than on the non-cleft side.

CLINICAL RELEVANCE

Given that obtaining a stable, functional, and esthetic occlusion requires a thorough evaluation of tooth size, knowledge about trends in tooth size variations in CLP patients can help with dental and orthodontic treatment planning.

Benefit of Temporomandibular Joint Lavage With Intra-Articular Steroids Versus Lavage Alone in the Management of Temporomandibular Joint Involvement in Juvenile Idiopathic Arthritis

PURPOSE

The aim of the present investigation was to evaluate, in patients with juvenile idiopathic arthritis, the effect of lavage with or without intra-articular corticosteroid (IACS) injection on clinical temporomandibular joint (TMJ) signs and symptoms of inflammation and changes in acute inflammation as assessed using magnetic resonance imaging (MRI).

MATERIALS AND METHODS

Forty-one patients (mean age, 13.6 ± 4.0 yr) with juvenile idiopathic arthritis participating in a large prospective juvenile inflammatory rheumatism cohort study (JIRcohorte) were included in this study. Clinical history, examination, and MRI were carried out at baseline and 6 months after intervention, if any. Twenty-one patients underwent lavage and IACS injection in at least 1 TMJ, 8 patients underwent lavage of at least 1 TMJ, and 12 patients were followed with no intervention. Outcomes measured were maximal mouth opening, Helkimo dysfunction index scores, pain intensity, and acute inflammation as assessed using MRI.

RESULTS

All groups showed a mean increase in mouth opening and mean decrease in pain intensity. The mean Helkimo clinical dysfunction score decreased for the 2 intervention groups but not for the control group. The mean Helkimo anamnestic dysfunction score decreased for the lavage with IACS group but not for the lavage-only group. The only statistically relevant difference was found for the Helkimo anamnestic dysfunction score comparing the lavage-only with the lavage with IACS group, with a more positive effect found in the lavage with IACS group. More than 50% of joints in each group showed no change at MRI examination. Joints with lavage and ICAS injection showed better improvement than joints that had lavage only or no intervention.

CONCLUSION

TMJ lavage with or without IACS injection cannot be claimed to systematically decrease pain, increase mouth opening, or resolve acute inflammation. Despite a tendency for improvement, response to this treatment is very patient dependent and can be determined by an array of other variables.

Autosomal dominant nonsyndromic cleft lip and palate: significant evidence of linkage at 18q21.1

Nonsyndromic cleft lip with or without cleft palate (NSCL/P) is one of the most common congenital facial defects, with an incidence of 1 in 700-1,000 live births among individuals of European descent. Several linkage and association studies of NSCL/P have suggested numerous candidate genes and genomic regions. A genomewide linkage analysis of a large multigenerational family (UR410) with NSCL/P was performed using a single-nucleotide-polymorphism array. Nonparametric linkage (NPL) analysis provided significant evidence of linkage for marker rs728683 on chromosome 18q21.1 (NPL=43.33 and P=.000061; nonparametric LOD=3.97 and P=.00001). Parametric linkage analysis with a dominant mode of inheritance and reduced penetrance resulted in a maximum LOD score of 3.61 at position 47.4 Mb on chromosome 18q21.1. Haplotype analysis with informative crossovers defined a 5.7-Mb genomic region spanned by proximal marker rs1824683 (42,403,918 bp) and distal marker rs768206 (48,132,862 bp). Thus, a novel genomic region on 18q21.1 was identified that most likely harbors a high-risk variant for NSCL/P in this family; we propose to name this locus "OFC11" (orofacial cleft 11).

Predictive factors of sagittal stability after treatment of Class II malocclusions

OBJECTIVE

To determine the existence of factors permitting the prediction of sagittal stability after orthodontic treatment in patients with Angle Class II malocclusion.

MATERIALS AND METHODS

PubMed, EMBASE, and the Cochrane Library were searched up to March 2015. Inclusion criteria were longitudinal studies with at least 10 subjects investigating associations between at least one factor and stability, with an average minimum follow-up period of 2 years; stability measured using posttreatment sagittal dental changes; and orthodontic treatment including removable and/or fixed appliances with or without extractions. Two reviewers independently selected and assessed the quality of the articles.

RESULTS

The search strategy resulted in 1372 articles, of which 17 met the inclusion criteria. Large changes during treatment in molar and canine relationships were the only two factors found to be positively associated with relapse, but with limited evidence. Fourteen factors were found not to be predictive of relapse, also with limited evidence. These factors included treatment characteristics, patient pretreatment characteristics, and final posttreatment characteristics.

CONCLUSIONS

There is currently limited evidence to support the influence of factors predictive of sagittal stability following Class II malocclusion treatment. More high-quality prospective studies are needed, and functional factors possibly affecting relapse also need to be further assessed.

Presurgical cleft lip anthropometrics and dental arch relationships in patients with complete unilateral cleft lip and palate

OBJECTIVE

To investigate associations between anthropometric lip measurements and dental arch relationships in patients with complete unilateral cleft lip and palate (CUCLP).

DESIGN

Retrospective cross-sectional study.

PATIENTS

Children with CUCLP.

METHODS

Anthropometric lip measurements, made immediately prior to lip repair, were available for each patient. The dental arch relationships were evaluated on dental study casts (8.6 ± 0.9 years) taken prior to any orthodontic treatment and prior to alveolar bone graft, using the modified Huddart and Bodenham (MHB) scoring system. The presence of associations between anthropometric lip measurements and dental arch relationships was determined using linear regression analysis.

RESULTS

In the 63 patients included in the study, the cleft lateral lip element was deficient in height in 87% and in transverse width in 86% of patients. Patients with more deficient cleft-side lateral lip height were more likely to present with more negative MHB scores (r = .443; P < .001). Conversely, patients with more deficient cleft-side lateral lip transverse width more often presented with more positive MHB scores (r = .281; P = .025).

CONCLUSIONS

In patients with CUCLP, there is a wide variability in the degree of deficiency of the cleft-side lateral lip element, both in the vertical and in the transverse dimension. The extent of this deficiency may, in part, predict the resulting dental arch relationships.

Gingival recessions of lower incisors after proclination by orthodontics alone or in combination with anterior mandibular alveolar process distraction osteogenesis

OBJECTIVES

The aim of this study was to longitudinally compare periodontal conditions in consecutive patients who had orthodontic treatment with proclination of lower incisors either by orthodontics alone or in combination with anterior mandibular alveolar process distraction osteogenesis (DO).

MATERIALS AND METHODS

Nineteen patients had orthodontic treatment with DO, 18 with extraction of lower premolars (Ex), and 18 without extractions (Nonex). Lateral cephalograms were used to evaluate lower incisor proclination, while study casts and intraoral photographs were used to evaluate labial and lingual gingival recessions before (T1) and at an average of 4.5 years (T2) after treatment.

RESULTS

No differences in labial recessions on lower incisors were present between the patient groups despite greater lower incisor proclination in the Nonex and DO groups. The Ex group showed no new development of lingual recessions in contrast to the Nonex (eight sites; two subjects) and DO groups (seven sites; three subjects). Severe lingual recessions (increased ≥1 mm) were more present in the Nonex group (five sites; two subjects) compared to the Ex group (no sites). Proclination of lower incisors of 10° or more either by orthodontic tooth movement or displacement of the whole alveolar process increased the risk of lingual gingival recessions 17 times. This was not the case with labial gingival recessions.

CONCLUSIONS

Orthodontic or surgical proclination of lower incisors beyond a 10° limit increases the risk of inducing lingual gingival recessions.

CLINICAL RELEVANCE

During orthodontic treatment, with or without DO, one should avoid proclining lower incisors more than 10° to decrease the risk of gingival recessions.

The 100 Most-Cited Human Cleft Lip and Palate–Related Articles Published in Dentistry, Oral Surgery, and Medicine Journals

Objective

To identify the 100 most-cited articles pertaining to human cleft lip and palate research published in dentistry, oral surgery, and medicine journals and to identify their principal bibliometric characteristics.

Design

Web-based bibliometric analysis.

Main Outcome Measure

The Web of Science was searched to identify the 100 most-cited clinical articles related to cleft lip and/or palate. Information was extracted with regard to total number of citations, number of authors, affiliations, year, and journal of publication, Medical Subject Headings, type of study, specific area of study. Trends in citations were assessed.

Results

The 100 most-cited articles identified received between 437 and 58 citations. The oldest was published in 1954 and the most recent in 2008. The number of authors ranged from 1 to 12, with an average of three authors per article. Most of the first authors were affiliated with institutions in the United States, with the most prolific institution being the University of Iowa. More than 70% of the studies appeared in The Cleft Palate–Craniofacial Journal. There was a significant negative correlation between average citations per year and time since publication ( P < .001); whereas, a significant positive correlation was observed between average citations per year and number of total citations ( P < .001).

Conclusions

The 100 most-cited articles in human cleft lip and palate research published in dentistry, oral surgery, and medicine journals are listed and characterized. This can be used as a potential knowledge base for specialists in training or to produce relevant knowledge defining the direction of future research.

Experiences Of Individuals Concerning Combined Orthodontic and Orthognathic Surgical Treatment: A Qualitative Twitter Analysis

OBJECTIVE

The aim of this qualitative study was to analyze the content of posts on Twitter in order to gain an in-depth understanding of patients' thoughts and experiences surrounding orthognathic surgical treatment.

MATERIALS AND METHODS

Using the Twitter search function, with the keywords "jaw surgery," the 1,000 most recent posts on Twitter with relevance to a combined orthodontic and orthognathic surgical treatment were extracted. After applying relevant inclusion and exclusion criteria, the selected posts were analyzed using thematic analysis by 2 independent investigators. Distinct themes and subthemes were developed.

RESULTS

A total of 689 posts were analyzed; the 3 main themes identified in relation to orthognathic surgery were preoperative engagement, postoperative difficulties, and posttreatment satisfaction. Twelve subthemes were also identified, expressing issues such as anticipation or apprehension of the surgical procedure, postoperative pain and edema, dietary restrictions and weight loss, paresthesia, depression, and satisfaction with improvements in appearance and self-confidence. The 6 terms most frequently used in tweets were "recovery," "braces," "swollen," "eat," "liquid diet," and "pain."

CONCLUSIONS

The findings from the present study can increase the awareness of clinicians involved in the combined orthodontic and orthognathic surgical treatment of patients with dentofacial deformities, allowing them to better educate and counsel their patients throughout the entire treatment process.

Predictive value of molar bite force on Class II functional appliance treatment outcomes

Sagittal intermaxillary changes brought about by functional appliances show large inter-individual variation. One factor that may in part explain these differences is the masticatory musculature and its functional capacity. The aims of this study were to investigate changes in maximal molar bite force during functional appliance treatment and to assess the influence of pre-treatment maximal molar bite force on treatment outcomes with functional appliances used in Class II malocclusion children. Twenty-five children (17 males and 8 females), aged 9-13 years, with a Class II malocclusion and increased overjet were treated with functional appliances for 1-2 years. Dental casts, lateral cephalograms, maximal molar bite force, and finger force measurements were performed before (T1) and after (T2) treatment. These same measurements were also performed 1-2 years before treatment (T0); the intermediate period before starting treatment served as the control. Multiple regression analyses were used to determine possible correlations between initial maximal molar bite force and dental or cephalometric changes during treatment. Maximal molar bite force, which increased pre-treatment (T0-T1), decreased during functional appliance treatment (T1-T2). Children with a weaker T1 maximal molar bite force showed a larger overjet reduction, greater improvement in molar relationship, greater reduction in ANB angle, and greater augmentation in SNB angle from T1 to T2. Treatment of children with Class II malocclusions with functional appliances seems to lead to more favourable treatment outcomes in those with a weaker maximal molar bite force. This was observed both as regards improvements in dental sagittal relationships, namely overjet and molar Class, as well as skeletal changes due to a decrease in ANB and an increase in SNB angles.

A Comparison of Craniofacial Characteristics between Two Different Adult Populations with Class II Malocclusion-A Cross-Sectional Retrospective Study

Simple Summary

One of the most common orthodontic problems, Class II malocclusion, may lead to an increased risk of dentoalveolar trauma, psychosocial issues, and a possible compromised quality of life. Oftentimes clinicians use normative standard values to which each patient is compared to identify deviations from the norm, in order to determine a patient-specific treatment plan. Large inter-individual and inter-ethnic variability, however, is sometimes not considered. In our study, we compared the cephalometric characteristics between two different ethnic groups (South Indian and Vietnamese) with the phenotype of Class II malocclusion in the hope of better understanding this variation and its implications in treatment planning to achieve satisfactory outcomes.

Abstract

The dental, skeletal, and soft-tissue characteristics of a particular malocclusion can differ based on ethnicity, race, age, sex and geographical location with Class II malocclusion being one of the most prevalent malocclusions encountered in orthodontic clinical practice. The broad understanding of the characteristics of vertical skeletal and dental parameters in patients with Class II malocclusion can help clinicians to identify patterns and variations in the expression of this phenotype for better treatment outcomes. Hence, we compared the craniofacial characteristics of skeletal and dental Class II malocclusion traits from Indian and Vietnamese individuals to analyze the vertical skeletal and dental patterns in both population groups. The sample comprised of lateral cephalograms from 100 young adults with Class II malocclusion, of which fifty (25 males and 25 females) were from South India and the other 50 age- and sex-matched adults from Vietnam. The lateral cephalometric radiographs were digitized into anonymous image files and were traced and assessed for 16 vertical skeletal and dental parameters. The ANB angle was greater in males (+1.4 deg; p < 0.001) and females (+1.9 deg; p < 0.001) in the South Indian population. The Vietnamese males had a larger mandibular plane angle, articular angle, anterior facial height and lower anterior facial height compared to the Indian males. The Vietnamese females had larger mandibular plane and articular angles compared to the Indian females. The skeletal class II malocclusion was more severe in the South Indian compared to the Vietnamese adults. The Vietnamese sample showed a generalized tendency towards a more vertical skeletal growth pattern and in males this pattern seemed to be due to the dentoalveolar component. The Vietnamese females showed a tendency towards a vertical growth pattern, but without apparent contribution by the dentoalveolar component.

Presurgical Unilateral Cleft Lip Anthropometrics and the Presence of Dental Anomalies

Objective

To investigate associations between cleft lip anthropometrics and dental anomalies in the permanent dentition in unilateral cleft lip patients.

Design

Retrospective cross-sectional study.

Patients

Children with unilateral clefts of the lip, with or without cleft palate.

Methods

Anthropometric lip measurements, made immediately prior to lip repair, were available for each patient. The presence of dental anomalies in the permanent dentition was assessed radiographically. The presence of associations between anthropometric lip measurements and prevalence rates of different dental anomalies were determined using logistic regression analyses.

Results

In the 122 included patients, the cleft lateral lip element was deficient in height in 80% and in transverse length in 84% of patients. Patients with more deficient cleft side lateral lip height and less deficient cleft side lateral lip transverse length were more likely to present with cleft side maxillary lateral incisor agenesis. On the other hand, patients with a less deficient cleft side lateral lip height and more deficient cleft side lateral lip transverse length were more likely to present with a cleft side supernumerary maxillary lateral incisor. When looking only at incomplete clefts, the cleft side lateral lip transverse length deficiency was more predictive of the presence of supernumerary maxillary lateral incisors (P= .030), while for complete clefts, the cleft side lateral lip height deficiency was more predictive of the presence of maxillary lateral incisor agenesis ( P = .035).

Conclusions

In patients with unilateral clefts, cleft lip anthropometrics have a predictive role in determining the occurrence of dental anomalies.

Evaluation of masseter muscles in relation to treatment with removable bite-blocks in dolichofacial growing subjects: A prospective controlled study

INTRODUCTION

The aim of this prospective study was to evaluate the effects of posterior bite-blocks on masseter muscles and on facial growth in prepubertal dolichofacial subjects.

METHODS

The treatment group comprised 21 consecutive prepubertal dolichofacial patients treated with rapid maxillary expansion followed by mandibular removable bite-blocks. Lateral cephalograms and ultrasonographic scans of the masseter muscles were made before (T1) and after (T2) treatment with bite-blocks. The treatment group was compared with a control group of 21 subjects matched for sex, age, and skeletal vertical pattern. An independent samples t test was used to compare the T1 to T2 changes in ultrasonographic scan measurements between the treatment group and the control group, and the T1 to T2 cephalometric changes in the treatment group. Regression analysis was performed to investigate associations between masseter muscle thickness and cephalometric treatment outcomes.

RESULTS

Masseter muscle thickness showed a statistically significant decrease (-0.7 mm) in the treatment group compared with an increase (+0.6 mm) in the control group. A significant anterior rotation of the mandibular plane was observed in the treatment group as well as significant increases in overbite (1.8 mm) and total posterior facial height (1.5 mm). No significant associations were found between masseter muscle thickness and treatment outcomes apart from a tendency for overbite to increase more in subjects with thicker muscles.

CONCLUSIONS

Treatment with removable bite-blocks produced a decrease in masseter muscle thickness and a reduction in vertical facial dimensions due to upward and forward rotation of the mandible. No significant correlation was found between the pretreatment masseter muscle thickness and the T1 to T2 cephalometric changes in the treatment group.

Differential influence of fluoride concentration on the synthesis of bone matrix glycoproteins within mineralizing bone cells in vitro

OBJECTIVE

This study investigated the influence of fluoride levels on the temporal synthesis of bone-associated glycoproteins, which have been assigned prominent roles in regulating crystal growth, size and shape during the mineralization process.

MATERIALS AND METHODS

Bone marrow stromal cells were isolated from male Wistar rats and cultured under mineralizing conditions, supplemented with 0 M, 10(-7) M or 10(-5) M sodium fluoride. The presence of bone-associated glycoproteins was examined 2-13 days post-reseeding by immunocytochemical localization. Results: All bone-associated glycoproteins increased in 10(-7) M fluoride, compared to untreated controls, particularly at days 6 and 13 in culture. Conversely, higher 10(-5) M fluoride concentrations decreased glycoprotein levels, compared to controls.

CONCLUSIONS

Results highlight a differential effect of fluoride concentration on glycoprotein synthesis by osteoblasts.

Treating Class II malocclusion in children. Vertical skeletal effects of high-pull or low-pull headgear during comprehensive orthodontic treatment and retention

OBJECTIVES

To evaluate, in Class II malocclusion children, vertical skeletal changes occurring with high- and low-pull headgear during non-extraction comprehensive orthodontic treatment, and retention.

SETTING AND SAMPLE POPULATION

Two groups of thirty Class II malocclusion children (mean age 10.8 years) who had undergone non-extraction comprehensive orthodontic treatment with either high- or low-pull headgear and fixed appliances.

MATERIAL AND METHODS

Retrospective longitudinal study, where pre-treatment, post-treatment and at least 2 year post-retention lateral cephalometric radiographs were analyzed. Comparisons were made concerning changes during treatment and retention in high- or low-pull headgear-treated children. Correlation analyses were carried out investigating changes in vertical cephalometric parameters and pre-treatment vertical facial pattern or type of headgear used.

RESULTS

During treatment, sagittal relationships improved in all children and remained stable during retention. Vertically, in both high- and low-pull headgear groups, the intermaxillary angle as well as the maxillary and mandibular plane angles did not show statistically significant changes during treatment or retention, and large variation was seen between patients. When pooling the whole patient sample, change in the vertical facial pattern was independent of the pre-treatment vertical facial pattern or type of headgear used.

CONCLUSION

When treating Class II malocclusion children non-extraction with high- or low-pull headgear and fixed appliances, changes in vertical skeletal relationships demonstrate wide variation, both during treatment and retention. Dentoalveolar changes brought about by these appliances may not be able to make a predictable difference in vertical skeletal patterns of growing patients.