Predictive value of masseter muscle thickness and bite force on Class II functional appliance treatment: a prospective controlled study

SummaryAim: To prospectively evaluate the functional capacity of the masticatory musculature as a predictive variable in determining functional appliance treatment outcomes in Class II/1 malocclusion children. Methods: Twenty Class II/1 malocclusion children (11.4±1.7 years) were treated with functional appliances during 1 year. Masseter muscle thickness and maximal molar bite force measurements, lateral cephalograms, and study casts were taken before and after treatment. Twenty age- and gender-matched untreated children were included as a control group. Regression analyses were used to identify correlations between pre-treatment muscle characteristics and treatment outcomes. Results: All treated patients showed dentoalveolar sagittal improvement. Maximal molar bite force and masseter muscle thickness decreased during the treatment period in the experimental group but increased in the control group. Children with lower pre-treatment maximal molar bite force showed more mesial movement of mandibular first molars, distal movement of maxillary first molars, and larger change in molar class during treatment. Children with thinner pre-treatment masseter muscles demonstrated more mandibular first molar mesialisation, mandibular incisor proclination, and opening of the gonial angle during treatment. Conclusions: The initial condition of the masticatory muscles may partly determine treatment outcomes. Children with thinner pre‐treatment masseter muscles or weaker bite force show greater dentoalveolar change

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 plannin

Craniofacial Cephalometric Characteristics and Open Bite Deformity in Individuals with Amelogenesis Imperfecta-A Systematic Review and Meta-Analysis.

BACKGROUND Individuals with amelogenesis imperfecta (AI) often present with malocclusions, especially a dental or skeletal anterior open bite (AOB). OBJECTIVES To evaluate the craniofacial characteristics in individuals with AI. MATERIAL AND METHODS A systematic literature search was conducted with the PubMed, Web of Science, Embase and Google Scholar databases to identify studies relating to the cephalometric characteristics of individuals with AI, without any language or publication date restrictions. The grey literature was searched using Google Scholar, Opengrey and Worldcat. Only studies with a suitable control group for comparison were included. Data extraction and a risk of bias assessment were carried out. A meta-analysis was performed using the random effects model for cephalometric variables that were evaluated in at least three studies. RESULTS The initial literature search yielded 1857 articles. Following the removal of duplicates and a screening of the records, seven articles were included in the qualitative synthesis, representing a total of 242 individuals with AI. Four studies were included in the quantitative synthesis. The meta-analysis results showed that individuals with AI present a smaller SNB angle and larger ANB angle than those of control groups in the sagittal plane. In the vertical plane, those with AI present a smaller overbite and larger intermaxillary angle than those without AI. No statistically significant differences were found for the SNA angle when comparing the two groups. CONCLUSIONS Individuals with AI seem to present with more vertical craniofacial growth, leading to an increased intermaxillary angle and decreased overbite. This possibly leads to a more retrognathic mandible with a larger ANB angle due to an anticipated posterior mandibular rotation

Bite force and its association with stability following Class II/1 functional appliance treatment

SUMMARY The aims of this study were to investigate the value of pre-treatment maximal molar bite force as a predictive variable in determining post-treatment changes and stability following functional appliance treatment in Class II malocclusion children. Twenty-eight Class II malocclusion children having undergone functional appliance treatment were followed for at least 1 year post-treatment. Maximal molar bite force measurements, lateral cephalograms, and study casts were taken before treatment, after treatment, and after post-treatment follow-up. Relationships between pre-treatment maximal molar bite force and dental or cephalometric changes post-treatment were examined. Patients were divided into stable and unstable groups, based on dental sagittal changes (overjet and molar relationship), and differences between the two groups of patients determined. Post-treatment changes varied widely. Thirteen children showed dentoalveolar sagittal relapse, namely a shift in molars towards a Class II relationship and an increase in overjet, while 15 did not. The unstable group demonstrated a lower pre-treatment maximal molar bite force, as well as a more obtuse gonial angle, than the stable group. The gonial angle was found to be negatively correlated to maximal molar bite force and may thus be a cephalometric indicator partly reflecting the functional condition of the masticatory muscles. Children with a lower pre-treatment maximal molar bite force were more prone to dentoalveolar sagittal relapse following functional appliance treatmen

An In Vitro Evaluation of the Effects of Air-Polishing Powders on Sound and Demineralised Enamel.

AIM To evaluate the effects of two air-polishing powders, during orthodontic treatment, on the surface roughness of sound and demineralised enamel. MATERIALS AND METHODS Forty-two caries-free human molars were collected, and the enamel surfaces were flattened and polished. Teeth were assigned to two groups (n = 21 each), a sound- and a demineralised-enamel group (subjected to pH-cycling over 2 weeks to create artificially induced white spot-like lesions). Within each group, teeth were further assigned to three groups (n = 7 each), air polished with either sodium bicarbonate, erythritol, or a negative control (water). Each sample was treated for 5 and 150 s. The average surface roughness (Ra) for each sample was measured using white-light-sensor profilometry. RESULTS On sound enamel, the Ra was roughly 0.17 ± 0.07 μm. After 150 s of air polishing, the Ra increased with erythritol (by 0.28 μm), and even more so with bicarbonate treatment (by 0.68 μm) (p < 0.01). On demineralised enamel, the Ra was roughly 0.79 ± 0.56 μm. The Ra increased after 5 s of air-polishing treatment similarly with erythritol and bicarbonate powders (by 1.03 μm and 1.04 μm, respectively) (p = 0.025), and even more after 150 s (by 2.48 μm and 2.49 μm, respectively) (p < 0.001). CONCLUSIONS On white spot lesions, one should be aware that enamel surface roughness will increase with both erythritol and bicarbonate air-polishing powders, especially with longer exposure times

Mandibular antegonial notch depth in postpubertal individuals: A longitudinal cohort study.

OBJECTIVES To perform an epidemiological analysis of the antegonial notch depth in postpubertal individuals and to analyze the development of deep antegonial notches longitudinally in growing individuals. MATERIAL AND METHODS: Lateral cephalograms of 302 untreated 17/18-year-old subjects (171 males; 131 females), from the craniofacial growth legacy collection, were analysed to measure antegonial notch depth along the mandibular plane. Sex and sagittal malocclusion were investigated as possible factors influencing notch depth. In subjects with deep antegonial notches (>1.5 standard deviation) at the age of 17/18 years, earlier lateral cephalograms at 7/8 and 13/14 years were obtained, and the magnitude of notch depth analyzed longitudinally. Linear regression analyses were used to assess correlations between antegonial notch depth and other recorded variables. RESULTS Antegonial notch depth ranged from 0 to 5.3 mm (mean 2.0 ± 1.0 mm). Antegonial notches were significantly deeper in males (2.3 ± 1.1 mm) than females (1.5 ± 0.7 mm) (p < .001). Notch depth was on average 0.3 mm deeper in Class I than in Class II or III individuals (p = .019). Twenty-one subjects (all male) were judged to have deep antegonial notches at the age of 17/18. In these subjects, notch depth deepened from 13/14 to 17/18 years (p < .001), whereas no change was observed between 7/8 and 13/14 years. CONCLUSIONS Antegonial notch depth shows important variation in postpubertal individuals, with males having deeper notches than females on average. In those with deep antegonial notches (all males in the present sample), notch depth increases not during prepubertal growth but during the pubertal growth spurt

Longitudinal changes of the insertion of the maxillary labial frenum in children and adolescents undergoing orthodontic treatment.

INTRODUCTION This study aimed to evaluate potential vertical changes in the position of the maxillary labial frenum (MLF) insertion in growing children and to compare these changes to the vertical growth of the dentoalveolar process and lower facial third. METHODS This retrospective longitudinal study investigated records of 33 healthy children. Dental casts, lateral cephalograms, and photographs were evaluated at pretreatment (T0), posttreatment (T1), and 3-5 years into retention (T2). To evaluate the vertical changes of MLF insertion in relation to the vertical growth of the dentoalveolar process, the palatal plane (PP) was used as a reference. These changes were also compared between different MLF typologies (ascribed as thin or fibrous). RESULTS The distance from MLF to PP only slightly increased from T0 to T2 by 0.6 ± 0.5 mm (P <0.001), whereas the distance between the incisal edge and PP increased significantly from T0 to T2 by 2.6 ± 0.8 mm (P <0.001). A positive correlation was found (r = 0.94; P <0.001) between the changes from the incisal edge to the PP and the MLF to the incisal edge between T0 and T2. No correlation was found between the change from the incisal edge to the PP and MLF to PP between T0 and T2. Thin MLF types showed a larger increase in distance from their insertion to the incisal edge (2.6 ± 0.8 mm) than thick MLF types (1.8 ± 0.7; P <0.03). CONCLUSIONS The MLF remains stable compared with the PP, whereas the maxillary incisal edge moves away from the PP, indicating increased vertical growth of the alveolar process. Dentists should be aware of those changes before performing interventions such as unnecessary frenectomies

Age-related transversal changes in craniofacial sutures of the anterior viscerocranium in growing rats.

Objective: To evaluate the dimensional changes that occur in the internasal and nasopremaxillary sutures, and related transverse craniofacial dimensions, of rats from 4 to 38-weeks of age. Methods: Four groups of twelve male Wistar rats were sacrificed at different ages [4-weeks (immature), 16-weeks (adolescent), 26-weeks (young adult), 38-weeks (adult)]. The rats were scanned with a high-resolution micro-computed tomography imaging device with 90 µm voxel size and 45 mm × 45 mm field of view (FOV) to obtain images of the viscreocranium, and with 10 µm voxel size and 5 mm × 5 mm FOV to obtain images of the internasal and left nasopremaxillary sutures. The nasal bone width, transverse width between the nasopremaxillary sutures and interzygomatic width were measured as craniofacial measurements. The endocranial, ectocranial and mean suture widths (cross-sectional area between endocranial and ectocranial borders/suture height), and suture height were measured at 5 frontal planes with 1.2 mm intervals. Outcomes were compared at different ages, and correlation coefficients were used to assess the relationship between craniofacial and suture changes. Results: All transverse craniofacial dimensions increased significantly from 4-16 weeks of age (p < 0.001). After 16-weeks of age, the only significant increase was observed in interzygomatic width (p = 0.02), between 26 and 38 weeks. In both the internasal and nasopremaxillary sutures, the endocranial suture mean widths decreased from 4-16 weeks (p < 0.001 and p = 0.002, respectively), but did not show any significant change after 16-weeks of age. The ectocranial internasal suture width decreased from 4-16 weeks (p < 0.001), increased until 26-weeks (p = 0.035), and subsequently decreased (p < 0.001). The nasopremaxillary suture widths decreased from 4-38 weeks to varying degrees in different frontal planes. Except for the internasal ectocranial suture width, all suture measurements were found highly and negatively correlated with the transverse craniofacial dimensions. The height of the sutures increased with time, with the most significant changes occurring between 4 and 16 weeks of age (p < 0.001). Conclusion: Although the internasal and nasopremaxillary endocranial suture widths nearly reach their final widths during adolescence, the changes in the ectocranial and mean suture widths continue into early adulthood. These results may serve as a reference for future studies aiming to evaluate the effects of functional demands on suture development and dimensional changes of the viscerocranium

Final Posttreatment Occlusion in Patients With Unilateral Cleft Lip and Palate

Objective: To evaluate final posttreatment occlusion in patients with complete unilateral cleft lip and palate (cUCLP) by comparing (1) 3 treatment centers, (2) males and females, (3) cleft and noncleft sides, (4) right- and left-sided clefts, and (5) orthodontic treatment with/without orthognathic surgery (OS). Design: Retrospective cohort study. Patients: Blinded posttreatment dental casts of 56 patients (19.4 ± 1.4 years) with cUCLP from 3 centers in Switzerland. Main outcome measure: Occlusal assessment using the modified Huddart/Bodenham (MHB) index. Results: Our sample comprised 35 males and 21 females, 46 with left- and 10 with right-sided clefts, of which 32 had undergone OS. The final posttreatment occlusion showed a median MHB score of 0 (interquartile range: -1.0 to 2.0) in the total sample and did not seem to depend on treatment center, sex, or OS. The MHB scores for the anterior buccal and the buccal segments were more negative on the cleft than on the noncleft side (P = .002 and P = .006, respectively). When the cleft was on the left side, the MHB score tended to be more positive in the labial (P = .046) and anterior buccal segments (P = .034). Conclusions: This study shows a very satisfactory final posttreatment occlusion in patients with cUCLP. The more constricted buccal occlusion on the cleft side emphasizes the attention that should be given in correcting the more medially positioned lesser maxillary segment. The influence of cleft-sidedness should be analyzed further on a sample including more patients with right-sided clefts. Keywords: Treatment outcome; cleft lip and palate; crossbite; dental arch relationships; dental occlusion; final post-treatment; multicentre study

Age-related transversal changes in craniofacial sutures of the anterior viscerocranium in growing rats

Objective: To evaluate the dimensional changes that occur in the internasal and nasopremaxillary sutures, and related transverse craniofacial dimensions, of rats from 4 to 38-weeks of age.Methods: Four groups of twelve male Wistar rats were sacrificed at different ages [4-weeks (immature), 16-weeks (adolescent), 26-weeks (young adult), 38-weeks (adult)]. The rats were scanned with a high-resolution micro-computed tomography imaging device with 90 µm voxel size and 45 mm × 45 mm field of view (FOV) to obtain images of the viscreocranium, and with 10 µm voxel size and 5 mm × 5 mm FOV to obtain images of the internasal and left nasopremaxillary sutures. The nasal bone width, transverse width between the nasopremaxillary sutures and interzygomatic width were measured as craniofacial measurements. The endocranial, ectocranial and mean suture widths (cross-sectional area between endocranial and ectocranial borders/suture height), and suture height were measured at 5 frontal planes with 1.2 mm intervals. Outcomes were compared at different ages, and correlation coefficients were used to assess the relationship between craniofacial and suture changes.Results: All transverse craniofacial dimensions increased significantly from 4–16 weeks of age (p &lt; 0.001). After 16-weeks of age, the only significant increase was observed in interzygomatic width (p = 0.02), between 26 and 38 weeks. In both the internasal and nasopremaxillary sutures, the endocranial suture mean widths decreased from 4–16 weeks (p &lt; 0.001 and p = 0.002, respectively), but did not show any significant change after 16-weeks of age. The ectocranial internasal suture width decreased from 4–16 weeks (p &lt; 0.001), increased until 26-weeks (p = 0.035), and subsequently decreased (p &lt; 0.001). The nasopremaxillary suture widths decreased from 4–38 weeks to varying degrees in different frontal planes. Except for the internasal ectocranial suture width, all suture measurements were found highly and negatively correlated with the transverse craniofacial dimensions. The height of the sutures increased with time, with the most significant changes occurring between 4 and 16 weeks of age (p &lt; 0.001).Conclusion: Although the internasal and nasopremaxillary endocranial suture widths nearly reach their final widths during adolescence, the changes in the ectocranial and mean suture widths continue into early adulthood. These results may serve as a reference for future studies aiming to evaluate the effects of functional demands on suture development and dimensional changes of the viscerocranium