Predictability of expansion movements performed by clear aligners in mixed dentition in both arches: a retrospective study on digital casts.

BACKGROUND: to evaluate the predictability of expansion achieved in patients in early mixed dentition treated with Clear Aligners (CA), analyzing the efficiency of the expansion at the end of the first set of aligners and at the end of the therapy in the upper and lower arch. METHODS: 36 patients (20 F, 16 M; mean age 8.3 ± 1.5 years) were selected retrospectively from the Department of Orthodontics of the Hospital of Rome "Tor Vergata". All subjects were treated with CA with no other auxiliaries than attachments. For each patient a standardized sequential expansion protocol was planned for both arches. Digital dental casts were created at three observation periods from an intraoral scanner: prior to treatment (T0), at the end of the first set of aligners (T1), at the end of treatment (T2). The 3D models in planned position determined by the first Clincheck (CC) were obtained for comparison with T1 and T2. Six linear transversal measurements were used to evaluate the dimensional changes and the predictability of expansion movements, comparing T1-CC and T2-CC. RESULTS: a statistically significant increase within the pre-treatment and the final outcomes for all the variables examined was found. In the upper arch, the greatest level of predictability was detected at the level of the first (46.44%) and second deciduous molar width (44.95%) at T1. The analysis of T2-CC changes showed a significant increase in the percentage of predictability of expansion at the level of the first permanent molars, at mesial (54.86%) and distal (58.92%) width. In the lower arch, a higher percentage of predictability than the upper arch was reported at T1-CC and T2-CC, with the greatest values at the level of second (T1-CC: 48.70%; T2-CC: 75.32%) and first deciduous molar width (T1-CC: 45.71%; T2-CC: 72.75%). CONCLUSIONS: CA can induce significant transversal increments. The predictability of expansion is variable, but it did not exceed the 50% during the first set of aligners. It was necessary to apply refinement set to achieve a good predictability for expansion of about 70%. The expansion in the lower arch was observed to be more predictable than in the upper arch.

Soft tissue evaluation of functional therapy in growing patients with Class II malocclusion: a long-term study.

OBJECTIVE: The objective of this study was to analyse the soft tissue changes produced by the functional treatment of mandibular advancement in growing Class II patients. MATERIALS: The treated group consisted of 25 Caucasian patients (12 females and 13 males) with dento-skeletal Class II malocclusion treated with functional therapy (Activator). All patients were evaluated before treatment (T1; mean age, 9.9 years), at the end of functional treatment phase (T2; mean age, 11.9 years), and at a post-pubertal follow-up observation (T3; mean age, 18.5 years). The treated group was compared with a matched control group of 25 untreated subjects (13 females, 12 males) with untreated Class II division 1 malocclusion. Statistical comparisons between the two groups were performed with independent samples t-tests (P < 0.05). RESULTS: Significant improvements were found during the long-term interval for mandibular sulcus (9.9°) and the profile facial angle (9.8°) in the treated group. No significant effects were found in terms of lower face percentage between the two groups. CONCLUSION: Removable functional appliances induced positive effects on the soft tissue profile in Class II growing subjects with good stability in the long-term.

Comparison of the dento-skeletal effects produced by Leaf expander versus rapid maxillary expander in prepubertal patients: a two-center randomized controlled trial.

OBJECTIVE: This study aimed to compare the skeletal and dentoalveolar effects produced by slow maxillary expansion (SME) with the Leaf expander versus the conventional rapid maxillary expansion (RME) on digital dental casts, lateral and postero-anterior cephalometric radiographs. TRIAL DESIGN: This is a superiority, two-center, two arms parallel balanced randomization trial. METHODS: Patients in the mixed dentition were included with a transverse interarch discrepancy of at least 3 mm. An expansion screw using moderate continuous forces (Leaf group) was compared to a conventional RME screw (RME group). The primary response variable was the difference in maxillary intermolar width (U6-U6) measured at baseline (T0) and one-year follow-up (T1) on the digital dental casts. Other dento-skeletal variables were also measured on digital dental casts and cephalograms. Computer-generated block randomization was used with allocation concealed in sequentially numbered opaque sealed envelopes. The examiner was blinded on the type of expander used. Linear models were used for statistical analysis. RESULTS: Twenty-eight patients in the Leaf group and 28 patients in the RME group were randomized and included in the study. There were no dropouts. U6-U6 did not show a statistically significant difference between the two groups (-0.4 mm in favor of the RME group, 95% CI from -1.2 to 0.5, P = 0.365). As for the other secondary variables no statistically significant differences were found between the two groups except maxillary intercanine width (U3-U3, -0.9 mm in favor of the RME group, 95%CI from -1.5 to -0.3, P = 0.005) and maxillary skeletal width (Mx-Mx, -1.4 mm in favor of the RME group, 95%CI from -2.4 to -0.3, P = 0.013). CONCLUSIONS: No significant differences between the RME and Leaf groups were detected for any of the analyzed dento-skeletal variables except the T1-T0 differences in U3-U3 and Mx-Mx that were significantly greater in the RME group. REGISTRATION: The study was registered in the ISRCTN register on 08/11/2016 with the number ISRCTN18263886. FUNDING: No funding or conflict of interest to be declared.

Effects of pendulum appliance versus clear aligners in the vertical dimension during Class II malocclusion treatment: a randomized prospective clinical trial.

BACKGROUND: The aim of the present study was to compare the effects on vertical dentoskeletal dimension produced by Pendulum appliance and Clear Aligners in patients with Class II malocclusion. TRIAL DESIGN: This is a prospective two-arm parallel group randomized clinical trial with 1:1 allocation ratio. METHODS: The Pendulum Group (PG) consisted of 20 patients (15F, 5 M) with a mean age of 17.2 ± 4.3 years. The Clear Aligners Group (CAG) comprised 20 patients (13F, 7 M) with a mean age of 17.2 ± 3.2 years. Distalization's protocol in PG involved the activation of TMA wires till the achievement of Class I molar relationship. A protocol of sequential distalization was applied in the CAG. For each subject lateral cephalograms have been analyzed before treatment (T1) and at the end of the therapy (T2). Descriptive statistics and statistical between-group comparisons (PG vs CAG) were calculated for the craniofacial starting forms at T1 and for the T2-T1 changes. Statistical between-group comparisons for the T2-T1 changes were performed with independent samples t-tests (P < 0.05). RESULTS: The PG showed significantly greater increases in SN^GoGn° when compared with CAG (+ 2.1 and - 0.3 degrees, respectively). Clockwise rotation of the occlusal plane with significantly greater increase of SN^POccl angle was observed in PG (+ 2.8 degrees) when compared with CAG (- 4.2 degrees). The PG revealed a significant increase in the N-Me variable with a mean change of + 4.4 mm compared to the CAG with mean values of - 1.2 mm. The PG showed an increase in the ArGo^GoMe angle (+ 0.7° degrees) compared to the CAG (- 3.4° degrees). The PG showed significantly greater increases in both maxillary and mandibular first molar to palatal plane (+ 1.3 and + 2.1 mm, respectively) when compared with CAG (- 0.9 and - 0.2 mm, respectively). CONCLUSIONS: Upper molar distalization with clear aligners represents a valid alternative to non-extraction treatment of Class II malocclusion, reducing the extrusion of maxillary first molars and improving the management of the occlusal plane and vertical dimension. TRIAL REGISTRATION: ClinicalTrials.gov, NCT05298280. Registered 28 March 2022-Retrospectively registered, https://clinicaltrials.gov .

Comparison between two screws for maxillary expansion: a multicenter randomized controlled trial on patient's reported outcome measures.

OBJECTIVE: The objective of this study was to compare an expansion screw of the maxilla that generates moderate and continuous forces versus a conventional screw for rapid maxillary expansion (RME) on patient-reported outcome measure during the first 12 weeks of treatment. TRIAL DESIGN: This is a superiority, multicenter, two-arm parallel balanced randomization trial. METHODS: Patients in the mixed dentition were included with a transverse discrepancy between the two arches of at least 3 mm. An expansion screw using moderate continuous forces (Leaf group, treated with an expansion screw with Ni-Ti springs) was compared to a conventional RME screw that generates intermittent heavy forces (RME group). The primary response variable was the visual analogue scale (VAS) on pain calculated in the first 12 weeks of therapy. The VAS on difficulty on speaking and oral hygiene, patient satisfaction, and complications were also evaluated. A computer-generated block randomization was used with allocation concealed in sequentially numbered opaque-sealed envelopes. Blinding was not applicable. Linear models were used for statistical analysis. RESULTS: Twenty-eight patients in the Leaf group and 28 patients in the RME group were randomized and included in the study. There were no dropouts. The mean of the VAS for pain was 0.3 ± 0.4 in the Leaf group and 0.6 ± 0.5 in the RME group. The difference was -0.3 (95 per cent CI from -0.5 to -0.0; P = 0.017) in favour of the Leaf group. The difference in pain was marked in the first week (Leaf group 2.2 ± 2.3; RME group 3.7 ± 2.6; difference -1.5; 95 per cent CI from -2.7 to -0.3; P = 0.019). CONCLUSIONS: Patients in the Leaf group experienced a lower degree of pain, especially during the first week following the application of the expander. For the other variables, no significant differences were reported between the two treatments. REGISTRATION: The study was registered in the ISRCTN register on 8 November 2016 with the number ISRCTN18263886.

Enamel interproximal reduction during treatment with clear aligners: digital planning versus OrthoCAD analysis.

BACKGROUND: The aim of the study was to compare the amount of interproximal enamel reduction (IPR) provided on ClinCheck software with the amount of IPR carried out by the orthodontist during treatment with clear aligners. METHODS: 30 subjects (14 males, 16 females; mean age of 24.53 ± 13.41 years) randomly recruited from the Invisalign account of the Department of Orthodontics at the University of Rome "Tor Vergata" from November 2018 to October 2019, were collected according to the following inclusion criteria: mild to moderate dento-alveolar discrepancy (1.5-6.5 mm); Class I canine and molar relationship; full permanent dentition (excluding third molars); both arches treated only using Comprehensive Package by Invisalign system; treatment plan including IPR. Pre- (T0) and post-treatment (T1) digital models (.stl files), created from an iTero scan, were collected from all selected patients. The OrthoCAD digital software was used to measure tooth mesiodistal width in upper and lower arches before (T0) and at the end of treatment (T1) before any refinement. The widest mesio-distal diameter was measured for each tooth excluding molars by "Diagnostic" OrthoCAD tool. The total amount of IPR performed during treatment was obtained comparing the sum of mesio-distal widths of all measured teeth at T0 and T1. Significant T1-T0 differences were tested with dependent sample t-test (P < 0.05). RESULTS: In the upper arch, IPR was digitally planned on average for 0.62 mm while in the lower arch was on average for 1.92 mm. As for the amount of enamel actually removed after IPR performing, it was on average 0.62 mm in the maxillary arch. In the mandibular arch, the mean of IPR carried out was 1.93 mm. The difference between planned IPR and performed IPR is described: this difference was on average 0.00 mm in the upper arch and 0.01 in the lower arch. CONCLUSIONS: The amount of enamel removed in vivo corresponded with the amount of IPR planned by the Orthodontist using ClinCheck software.

Changes in mandibular shape after early treatment in subjects with open bite: a geometric morphometric analysis.

OBJECTIVES: To evaluate the mandibular modifications in anterior open bite (OB) growing subjects treated with Rapid Maxillary Expansion and bite block (RME/BB) or Quad Helix with crib (QH/C) when compared with a Control Group (CG) by using Geometric Morphometric Method (GMM) and conventional cephalometric. MATERIALS: The OB group comprised 34 subjects (26 girls, 8 boys) with dentoskeletal OB and a mean age of 8.0 ± 1.0 years. OB group was divided in two subgroups: RME/BB group comprised 17 subjects (13 girls, 4 boys), while QH/C group included 17 subjects (13 girls, 4 boys). The two subgroups were compared with a CG of 17 subjects (13 girls, 4 boys) matched for sex, age, vertical pattern, and observation periods. Two consecutives lateral cephalograms were available: the first one was taken before treatment (T1), and the second one was acquired at a follow-up observation at least 4 years after the completion of treatment (T2). Landmarks and semilandmarks were digitized on lateral cephalograms and GMM was applied. Procrustes analysis and principal component analysis were performed. Analysis of variance (ANOVA) with Tukey post hoc tests was used to compare the T2-T1 cephalometric changes between the RME/BB, QH/C, and CG. RESULTS: In the long term, RME/BB showed a significantly greater decrease of the Condylar axis to mandibular plane angle when compared to CG and QH/C. GMM showed an increased in height of the mandibular ramus in RME/BB group with tendency to counterclockwise rotation of the mandible when compared with QH/C and CG groups. CONCLUSIONS: RME/BB subjects showed significant changes in the shape of the mandibular ramus with a counterclockwise rotation tendency when compared with QH/C and CG subjects.

Conventional versus laser gingivectomy in the management of gingival enlargement during orthodontic treatment: a randomized controlled trial.

OBJECTIVES: To compare the use of diode laser with conventional surgery evaluating the effectiveness of gingivectomy as an adjunct to non-surgical periodontal treatment in the management of gingival enlargement (GE) during orthodontic treatment. TRIAL DESIGN: Prospective three-arm parallel group randomized clinical trial with 1:1:1 allocation ratio. METHODS: Sixty subjects (33 males and 27 females), with a mean age of 14.4 ± 1.9 years, were selected according to inclusion criteria: overgrown gingivae on the labial side of the anterior teeth secondary to fixed appliance therapy, six maxillary anterior teeth present, and healthy non-smokers patients. Patients were enrolled in the study and randomly assigned to three groups by a computer-generated randomization list and by a block size of 4. The allocation information was concealed in opaque and sealed envelopes by the statistician. In the first group, all subjects underwent a conventional scalpel gingivectomy of the maxillary anterior sextant. In the second group, all subjects were treated using laser-assisted gingivectomy; while subjects assigned to the third group underwent only non-surgical periodontal treatment and served as control group (CG). The observer who performed all the measurements was blinded to the group assignment. Blinding was obtained by eliminating from the elaboration file every reference to patient group assignment. Intergroup comparisons of changes in the periodontal parameters were conducted at 1, 3, and 6 months using ANOVA with repeated measures and Tukey's post hoc tests. The significance level was set at P <0.05. RESULTS: After 1 month, the TGs showed a significant improvement of all periodontal parameters when compared with the CG. No statistically significant differences were observed between the two TGs. At the 3-month observation, a relapse occurred in the TGs, while the CG showed the greater improvement of soft tissue health. In the 6-month versus 3-month evaluation, no significant differences between the three groups were found for any periodontal measurements. In the long-term evaluation (6 months versus baseline), a significant greater reduction of pockets were found in the TGs when compared with the CG. CONCLUSIONS: The adjunct use of both scalpel gingivectomy and laser gingivectomy was more effective in controlling gingival inflammation than non-surgical periodontal treatment alone at 1, 3 and 6 months. In the control group, greater improvement in the periodontal parameters were observed within 3 months, depending on a self-care approach for the management of GE. LIMITATIONS: This study was a short-term study (6-month follow-up). TRIAL REGISTRATION: ClinicalTrials.gov (registration number: NCT03514316).

Efficacy of ketoprofen lysine salt and paracetamol/acetaminophen to reduce pain during rapid maxillary expansion: A randomized controlled clinical trial.

BACKGROUND: Rapid maxillary expansion (RME) is an orthopaedic procedure indicated for a wide variety of clinical conditions. AIM: The aim of the study was to compare the effects of ketoprofen lysine salt (KLS) vs paracetamol/acetaminophen (P) on pain perception during RME. DESIGN: One hundred and fifty-one subjects (mean age 8.6 year) were enrolled in this prospective controlled clinical trial according to inclusion criteria: prepuberal stage of development, negative posterior transverse interarch discrepancy, non-concurrent use of other drugs. First phase: n.40 allocated to Group 1 used 40 mg of KLS, n.40 to Group 2 used 250 mg of P, n.36 to Group 3 as control group. Second phase: n.35 allocated to Group 4 used 40 mg ketoprofen lysine salt once a day for the first 3 days of activation. Pain experience was reported on a numeric rating scale (0-4) and a 100-mm visual analogue scale. Pain perception was tested with the Mann-Whitney test (P < 0.05). RESULTS: Pain perception was higher during the first 3 days of activation and it was described as mild to moderate. Group 1 experienced significantly less pain during the fourth, fifth, and sixth day (P < 0.05) compared with Group 2. Patients of the Group 4 reported significantly lower pain during the whole period of RME activation (P < 0.05). CONCLUSIONS: The perceived higher pain was reported during the second and third day of expansion. The analgesic effect of KLS is more effective than P during the fourth, fifth, and sixth day. The use of KLS during the first 3 days of activation seems to be able reducing pain during the whole active phase.

Three-dimensional airway changes after adenotonsillectomy in children with obstructive apnea: Do expectations meet reality?

INTRODUCTION: The assessment of the volumetric changes of the airways after adenotonsillectomy has gained popularity among orthodontists, but the validity of such evaluation is not clear. METHODS: Thirty patients with obstructive sleep apnea diagnosed with the use of polysomnography (PSG) were evaluated according to the Apnea and Hypopnea Index (AHI), the obstructive apnea index (OAI), the oxygen desaturation index (ODI), the lowest oxygen saturation (LSpO2), and the average oxygen saturation (ASpO2). The volume and the minimal cross-section of lower (oropharynx and velopharynx) and upper (nasopharynx) spaces of the airways were calculated. Patients were adenotonsillectomized; posttreatment data were collected after 12 months. Thirty comparison patients also had the volume of airways evaluated. RESULTS: A statistically significant improvement (P < 0.05) of most PSG parameters was observed after adenotonsillectomy: AHI from 14.5 to 5.2, OAI from 9.4 to 5.5, ODI from 14.6 to 6.5, and LSpO2 from 77% to 94%). A significant increase in airway volume of the lower space (from 2571.5 mm3 to 5276.3 mm3) and the upper space (from 726 mm3 to 1056.9 mm3), as well as in the minimal cross-section of the airways (from 98.5 mm2 to 335.8 mm2) was found in adenotonsillectomy patients. No significant volumetric changes of the airways were observed in the comparison patients. No significant correlation was found between PSG parameters and the dimensions of the airways before adenotonsillectomy. No significant correlation was found between changes of the PSG parameters and changes of the dimensions of the airways 12 months after the adenotonsillectomy. CONCLUSIONS: Adenotonsillectomy contributed to the increase of the airway volume and minimal cross-section, and to the improvement of the PSG parameters, but there was no correlation between the magnitude of the anatomic changes and the improvement of the breathing mode.

Long-term stability of curve of Spee levelled with continuous archwires in subjects with different vertical patterns: a retrospective study.

OBJECTIVES: The aim of the study was to evaluate the curve of Spee (COS) stability in patients treated with continuous archwires with different vertical patterns. METHODS: The study sample consisted of 60 patients (28 males, 32 females; mean age 19.8 ± 1.4 years) presenting with COS depth of at least2 mm at baseline. For each subject, lateral cephalograms and dental casts were available before treatment (T1), at the end of orthodontic therapy (T2), and 2 years after the end of treatment (T3). All subjects were divided into three groups according to vertical facial patterns. Cephalometric parameters were used to evaluate the dental movements after treatment. COS depth was measured on digital casts. Mean differences between vertical facial subgroups were contrasted by means of analysis of variance test (P < 0.01). RESULTS: In low-angle subjects, COS levelling occurred through advancement and intrusion of lower incisors, whereas in high-angle patients, the COS was flattened through extrusion and uprighting of lower posterior teeth. In the low-angle group, a significant relapse of lower incisors inclination was observed. Differently, the high-angle group exhibited a greater stability of COS obtained by stable extrusion of posterior teeth. CONCLUSIONS: The long-term instability of flared incisors determined the relapse of overbite and COS depth in the low-angle group.

Soft tissue facial profile in Class III malocclusion: long-term post-pubertal effects produced by the Face Mask Protocol.

OBJECTIVES: The objective of this study was to analyze soft tissue changes produced by rapid maxillary expansion and facial mask therapy in growing Class III patients. MATERIALS: The treated group consisted of 32 Caucasian patients (15 females and 17 males) with dentoskeletal Class III malocclusion treated with the Face Mask Protocol (FMP, rapid maxillary expander, facial mask, and removable lower bite-block). All patients were evaluated before treatment (T1; mean age, 8.4 years), at the end of active treatment (T2; mean age, 10.7 years), and at a post-pubertal follow-up observation (T3; mean age, 15.8 years). The treated group was compared with a matched control group of 20 untreated subjects (10 females and 10 males) with dentoskeletal Class III malocclusion. Statistical comparisons between two groups were performed with the independent samples t-test (P < 0.05). RESULTS: Significant improvements were found during the long-term T1-T3 interval for profile facial angle (-5.8°), nasolabial angle (-4.4°), mandibular sulcus (-10.3°), upper lip protrusion (+0.7 mm), and lower lip protrusion (-1.1 mm) in the treated group. No significant post-pubertal effects were found in terms of lower face percentage between two groups. LIMITATIONS: This study has a retrospective design and it used a historical control sample. CONCLUSION: The FMP induced positive effects on soft tissue facial profile with a good long-term post-pubertal stability.

Geometric morphometric analysis of the palatal morphology in growing subjects with skeletal open bite.

OBJECTIVES: To assess the morphological shape variations of the palatal vault in Open Bite (OB) growing subjects when compared with a Control Group (CG) by means of Geometric Morphometric Method (GMM). MATERIALS AND METHODS: The OB Group (OBG) consisted of 75 subjects (39 females, 36 males; mean age: 8.5 ± 0.8 years) who were collected retrospectively with the following inclusion criteria: European ancestry, overbite less than 0 mm, mixed dentition stage, prepubertal skeletal maturation (CS1-CS2), hyperdivergent skeletal pattern (SN^GoGn > 37°). The OBG was compared with a CG of 46 prepubertal subjects presenting normal occlusion (24 females, 22 males; mean age of 8.3 ± 1.7 years). For each subject, lateral cephalograms and maxillary dental casts were available. Landmarks and semilandmarks were digitized on digital dental casts and GMM was applied. Procrustes analysis and principal component analysis (PCA) were performed. OBG was divided in two subgroups: Sucking Habits Group (SHG) (39 subjects) and Non-Sucking Habits Group (NSHG) (36 subjects). RESULTS: PC1 showed significant morphological changes in transverse and vertical dimensions with OBG palates higher and narrower when compared with CG. When comparing the two subgroups no statistically significant differences were found. NSHG demonstrated a slight reduction of the transverse dimension and a deeper palatal vault respect to SHG. LIMITATIONS: The limitations of this study were the division of OBG in two subgroups based on referral of thumb sucking habits without assessing the duration and the intensity of thumb sucking. CONCLUSIONS: OB subjects presented with a significant constriction of the maxillary arch when compared with CG. The morphological palatal shape variations in OBG were not influenced by the presence or absence of non-nutritive sucking habits.

Comparison of the abrasive properties of two different systems for interproximal enamel reduction: oscillating versus manual strips.

BACKGROUND: The aim of the present investigation was to evaluate enamel reduction efficiency, abrasive property decay, and enamel effects between oscillating mechanical and manual systems for interproximal enamel reduction (IPR). METHODS: Three oscillating strips and three manual strips were tested on twelve freshly extracted premolars blocked in an acrylic cylinder pot by means of a material testing machine. Each strip underwent one test of 8 cycles (30 s each). Both abrasive tracks and teeth surfaces were qualitative evaluated before and after IPR by means of SEM analysis. Efficiency and abrasive property decay of both IPR systems were investigated by the amount of enamel reduction within the eight-cycle testing. Independent t-test was used to evaluate differences in variables between the two systems. RESULTS: Mechanical IPR system showed higher efficiency in terms of enamel reduction (p < 0.005) when compared with manual IPR system (0.16 mm and 0.09 mm, respectively). Quantity of removed enamel decreased throughout the 8 cycles for both systems. Less presence of enamel debris and detachment of abrasive grains were observed on mechanical strips rather than manual strips. SEM analysis revealed more regular surface of teeth undergone mechanical IPR procedures. CONCLUSION: Oscillating diamond strips showed more controlled efficiency when compared with the manual IPR system leading to a more regular enamel surface.

Stress on facial skin of class III subjects during maxillary protraction: a finite element analysis.

BACKGROUND: Maxillary protraction with facemask (FM) is an orthopedic approach for treatment of Class III growing patients. Aim of the present investigation was to analyze tension loads produced by two different facial mask (FM) designs on facial skin of subject with skeletal Class III. METHODS: A three-dimensional (3D) geometry of Delaire and Petit FM models were reconstructed from the original Computer Aided Design (CAD) 3D prototype using software package (ANSYS 5.7). A traction load of 9.8 N inclined of 30° to the occlusal plane was applied combining analytical FM models with a 3D facial model. Resulting stresses and deformations on the skin layer were tested through the von Mises yield criterion. RESULTS: Overall tensions were mostly developed on the chin area, while lower stresses were observed on forehead area for both FM designs. When Delaire FM model was tested, maximum stresses were observed on the upper border of the chin cup corresponding to the inferior lip and to marginal gingiva of lower incisors. After Petit FM application, maximum stresses were more extensively localized at the level of both upper border and central area of the chin. Stresses measured on the chin area were significantly higher with Petit FM when compared with Delaire FM (44 KPa versus 29 KPa, respectively). CONCLUSIONS: Delaire FM determined lower stresses and tensile tensions than Petit FM model. Highest tensions were observed at the level of chin cup area for both Delaire and Petit FM. Stresses following Delaire FM application were mostly observed on the upper border of the chin cup, while Petit FM determined stresses more extensively distributed to the central area of the chin.

Ultrasonographic Evaluation of The Effects of Orthodontic or Functional Orthopaedic Treatment on Masseter Muscles: A Systematic Review and Meta-Analysis.

Objectives: This review investigated the effects of orthodontic or functional orthopedic therapy on masseter muscle thickness through the use of ultrasonography (US) in growing subjects when compared with untreated subjects. Materials and Methods: This review systematically assessed studies that investigated growing subjects undergoing orthopedic therapy for the correction of malocclusion of vertical, sagittal and transversal plane. Electronic databases (CENTRAL, MEDLINE-PubMed, Scopus and Web of Science) were searched up to February 2019, including available RCTs and CCTs, without language restrictions. The primary outcome was the effect of orthopedic or functional treatment on masseter muscle thickness. The risk of bias of included studies was assessed through the Newcastle-Ottawa quality assessment scale with the aim of defining their methodological quality. A random-effects meta-analysis analyzing mean differences with 95% confidence intervals was used for quantitative analysis. Results: The search retrieved 749 titles, but the studies selection resulted in a final sample of 5 CCTs. The studies retrieved data from 233 children (age range: 5-22 years) and were conducted at university dental clinics. Children were treated for Class II malocclusion, increased vertical dimension or lateral cross-bite variably with rapid or slow maxillary expansion, twin block, bite block, mandibular activators, quad helix, alone or in combination. Risk of bias was assessed as medium for three studies, low for one and high for another. The meta-analysis determined that at the end of orthopedic or functional treatment masseter muscle thickness, measured through the use of US, is significantly reduced (MD -0.79 mm; 95% CI -1.28 to -0.31). The reduction in muscle thickness, therefore, could be considered an indicator for the evaluation of the success of therapy with orthodontic appliances. Conclusions: Although the meta-analysis revealed that US could be considered a less invasive and effective method to evaluate the masseter muscle thickness, single-blinded RCTs, are required to confirm US reliability in this field of application. This review was registered on PROSPERO with the following registration number: CRD42018068402.

Treatment timing for functional jaw orthopaedics followed by fixed appliances: a controlled long-term study.

Objective: To evaluate the role of treatment timing on long-term dentoskeletal effects of Class II treatment with removable functional appliances followed by full-fixed appliance therapy. Materials and methods: A group of 46 patients (23 females and 23 males) with Class II malocclusion treated consecutively with either Bionator or Activator, followed by fixed appliances was compared with a matched control group of 31 subjects (16 females and 15 males) with untreated Class II malocclusion. The treated sample was evaluated at T1, start of treatment (mean age: 9.9 ± 1.3 years); T2, end of functional treatment and prior to fixed appliances (mean age: 11.9 ± 1.3 years); and T3, long-term observation (mean age: 18.3 ± 2.1 years). The treated and the control samples were divided into pre-pubertal and pubertal groups according to skeletal maturity observed at the start of treatment. Statistical comparisons were performed with independent sample t-tests. Results: When treatment was initiated before puberty, Class II correction was mostly confined to the dentoalveolar changes, with significant improvements of both overjet and molar relationships. On the other hand, treatment with the outset at puberty produced significant long-term improvement of sagittal skeletal relationships, which were mainly sustained by mandibular changes. Conclusions: Treatment with removable functional appliances (Bionator or Activator) followed by full-fixed appliances produced significant skeletal long-term changes when it begins at puberty. Prepubertal Class II treatment results primarily in dentoalveolar changes.

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.

Morphometric covariation between palatal shape and skeletal pattern in Class II growing subjects.

OBJECTIVES: To evaluate the patterns of covariation between palatal and craniofacial morphology in Class II subjects in the early mixed dentition by means of geometric morphometrics. METHODS: A cross-sectional sample of 85 Class II subjects (44 females, 41 males; mean age 8.7 years ± 0.8) was collected retrospectively according to the following inclusion criteria: European ancestry (white), Class II skeletal relationship, Class II division 1 dental relationship, early mixed dentition, and prepubertal skeletal maturation. Pre-treatment digital 3D maxillary dental casts and lateral cephalograms were available. Landmarks and semilandmarks were digitized (239 on the palate and 121 on the cephalogram) and geometric morphometric methods (GMM) were applied. Procrustes analysis and principal component analysis (PCA) were performed to reveal the main patterns of palatal shape and craniofacial skeletal shape variation. Two-block partial least squares analysis (PLS) assessed patterns of covariation between palatal morphology and craniofacial morphology. RESULTS: For the morphology of the palate, the first principal component (PC1) described variation in all three dimensions. For the morphology of the craniofacial complex, PC1 showed shape variation mainly in the vertical direction. Palatal shape and craniofacial shape covaried significantly (RV coefficient: 0.199). PLS1 accounted for more than 64 per cent of total covariation and related divergence of the craniofacial complex to palatal height and width. The more a Class II subject tended towards high-angle divergence, the narrower and higher was the palate. CONCLUSIONS: Class II high-angle patients tended to have narrower and higher palates, while Class II low-angle patients were related to wider and more shallow palates.