Neuromuscular Stability of Dental Occlusion in Patients Treated with Aligners and Fixed Orthodontic Appliance: A Preliminary Electromyographical Longitudinal Case-Control Study.

The aim of the present study was to evaluate if, after treatment with aligners (ALIGN) and fixed orthodontic appliance (FOA), alterations of the neuromuscular activity may occur and if differences in these changes can be detected between the two treatments. Sixteen healthy patients (7 FOA, 9 ALIGN) with class I or class II molar relation were recruited. Standardized surface electromyography (ssEMG) was used to evaluate the activity of the masticatory muscles (masseters-MM and temporalis-TM) before the beginning of the orthodontic treatment (T1), at the end (T2), and 3 months (T3) after the end of the treatment. Intragroup (within timepoints) and intergroup differences were statistically analyzed. At T1, the mean values of each ssEMG index were within the normal range in both groups. At T2, the FOA group showed larger differential recruitment of the MM than TA muscles with a value slightly over the normal range. All the indexes were normalized at T3, and no differences emerged between groups. In the FOA group, the index of MM symmetrical contraction increased significantly at T3 compared to T1 and T2. In the ALIGN group, no significant changes were observed between each timepoint. In FOA subjects, a slight alteration of the muscular activity appeared immediately after bracket removal and this alteration normalized after 3 months of rescue. In subjects treated with aligners, no significant alteration of the muscular activity was assessed.

ssEMG assessment of a new tool for the management of 3D vertical dimension of occlusion in prosthetic dental rehabilitations: A case report.

In oral rehabilitation the new dental morphology requires changes in the occlusal relations and in case of whole dental arch restoration also the mandibular position can undergo three-dimensional spatial modifications. Overloads and/or altered distributions of the stresses on the temporomandibular joint, teeth and bones may therefore result with not clearly understood consequences. In the present case report a new tool -Vertical Tester- designed to manage the 3D vertical occlusion during an implant retained full mouth rehabilitation was combined with standardized surface electromyographic (ssEMG) analysis in order to respect the masticatory muscle symmetry and coordination. The Authors conclude that the standardized surface electromyography of the masticatory muscles coupled with custom made centric relation registration device is an easy to use procedure to reduce torsional strains on the oral hard structures.

Electromyographic analysis of the oral phase of swallowing in subjects with and without atypical swallowing: A case-control study.

BACKGROUND: Swallowing is a complex physiologic function developing mostly in the first years of life. After 6 years old, if mature deglutition is not achieved, swallowing persists as "atypical swallowing" (AS). OBJECTIVE: The aim of this study was to detect any electromyographical differences in the muscular activation pattern in patients with and without AS. MATERIALS AND METHODS: 38 adolescents and young adults were selected for this study: 20 with atypical swallowing (AS group) and 18 without (C group). Standardised surface electromyographic analysis was performed by the same operator to detect the activity of masseter (MM), temporalis (TA) and submental (SM) muscles. A Student t test for unpaired data was carried out to detect differences between the AS and C groups. A 1-way ANOVA was performed to detect any differences between the three couples of muscles. RESULTS: When compared to controls, AS patients showed a significantly longer duration of activity for each couple of muscles and for the whole duration of swallowing act (P < 0.0001) as well as lower intensity of the SM activity (P < 0.05) than controls. Within the AS and C groups, masticatory muscles (MM and TA) showed lower duration of activation (P < 0.01) and lower intensity of the spike (P < 0.0001) than SM. Within the C group, masticatory muscles also reached their activation spike earlier (1-way ANOVA, P < 0.01) than SM. CONCLUSION: Two different muscular performance models have been defined: patients with AS showed a longer activity of all the muscles involved with a lower intensity of SM activity than that of controls.

Standardised surface electromyography allows effective submental muscles assessment.

The aims of this pilot study were to evaluate: (i) the reproducibility and variability of an electromyographical protocol developed for the assessment of submental muscles (SM) (ii) to apply the new protocol to maximal teeth clenching, a simple and largely studied static task in order to quantify the relative contribution of submental muscles. In 20 healthy subjects, aged 19-35years, surface electromyography of SM, masseter (MM) and anterior temporalis (TA) muscles was performed during maximal voluntary clenching (MVC) with and without cotton rolls and the pushing of the tongue against the palate. Clenching on cotton rolls and pushing the tongue against the palate were used to standardise respectively MM and TA, and SM muscular potentials. The exercises were repeated in two appointments (T1-T2); submental muscles standardisation was also repeated twice (A-B) in each session to assess repeatability. Symmetry and activity were calculated for each couple of muscles. A two-way analysis of variance was computed for SM: no Factor 1 (T1 vs T2) or Factor 2 (A vs B) or F1×F2 significant effects were found. SM recruitment was 31% of the maximal activity, with symmetry values larger than 80%. In conclusion, standardised electromyography allows a reliable assessment of Submental muscles activity.

Osseointegration of Titanium Implants With Different Rough Surfaces: A Histologic and Histomorphometric Study in an Adult Minipig Model.

BACKGROUND: Many chemical and physical modifications of titanium surfaces were introduced, aiming at improving surface bioactivity, but few comparative evidence exists. OBJECTIVE: To evaluate histologically in minipigs the osseointegration of implants made of commercially pure (CP) titanium or titanium alloy, treated by different roughening procedures. MATERIAL AND METHODS: Three sandblasted acid-etched (SA) surfaces, 2 anodized (AN), and 1 double acid-etched (DAE) were compared. Surface microtopography was characterized with scanning electron microscope; surface element composition was also assessed. One implant per group was inserted in each proximal tibia of 2 minipigs. Three months after healing, block biopsies were taken for histomorphometric analysis. Implant stability quotient (ISQ) was measured at insertion and before harvesting. RESULTS: The highest amount of cortical bone-implant contact was observed around SA implants and showed positive correlation with surface roughness. The greatest increase in ISQ was observed in CP-AN implants. In the medullary region, SA implants showed the best osteogenic response, whereas inflammatory cells were found around DAE and alloy-AN implants. CONCLUSIONS: SA surfaces were more osteogenic than anodized or dual acid-etched ones, although not significantly. Surface roughness affected osseointegration.

Iliac Crest Fresh-Frozen Allografts Versus Autografts in Oral Pre-Prosthetic Bone Reconstructive Surgery: Histologic and Histomorphometric Study.

PURPOSE: The aim of this work was to compare histologically bone biopsies obtained during dental implant placement in atrophic jaws reconstructed with fresh-frozen bone (FFB) or autologous bone blocks. MATERIALS AND METHODS: Twenty partially or totally edentulous patients were treated either with iliac crest FFB grafts (14 patients; group A) or with iliac crest autografts (6 patients; group B). Seven to 9 months later, dental implants were placed in the reconstructed jaws and bone biopsies were harvested. RESULTS: The reconstructive procedure was uneventful in 9 patients of group A and in all patients of group B. Samples from both groups did not show relevant differences concerning the proportion of lamellar bone, newly formed bone, and bone marrow. In group A, the decreasing proportion of blood vessels from the apical to the coronal portion, the larger amount of lacunae in the apical portion, and the fewer vessels in the coronal portion than in group B evoke an effort of the host bone to "integrate" the graft from the apical portion. CONCLUSIONS: FFB cannot be considered as successful and safe in alveolar bone reconstruction as autogenous bone grafting.

Histological and Histomorphometrical Evaluation of Postextractive Sites Grafted with Mg-Enriched Nano-Hydroxyapatite: A Randomized Controlled Trial Comparing 4 Versus 12 Months of Healing.

BACKGROUND: Tooth extraction generally results in an alveolar bone loss and structural changes in the overlying soft tissue. The amount of this relocation might jeopardize prosthetically driven implant placement. Thus, there is a high interest in techniques, materials and timing to minimizing tissue resorption, using postextraction ridge preservation procedures. PURPOSE: To assess by histological techniques, the outcomes of a socket preservation technique at 4 or 12 months after treatment with a magnesium-enriched hydroxyapatite (Mg-e HA). MATERIALS AND METHODS: Postextraction site in 20 patients underwent ridge preservation procedure. Mg-e HA granules were mixed with blood and grafted into the socket. A bone specimen was collected from each site before implant placement after 4 or 12 months randomly. Each biopsy was processed for undecalcified histological analysis. All ground sections were observed under light and polarized microscope. A semi-quantitative analysis by mean of stereological method was performed to evaluate the average volume fractions of bone, biomaterial and medullary spaces, and the percentage of blood vessels for both timepoints. Nonparametric Mann-Whitney U test for unpaired data was used to detect eventual statistical differences between groups. RESULTS: Histologically, the biomaterial appeared surrounded by newly formed bone in both groups without inflammatory infiltrate. At 4 months, the remodeling process of collagen matrix was starting from the apical portion toward coronal direction and was more active around grafted particles. At 12 months, the alveolar socket was completely regenerated and filled with mineralized and well-organized bone tissue around the residual biomaterial particles. In both groups, vessels were present to supply tissues around the graft (at 4 months: 4.95% ± 2.49; at 12 months: 7.45% ± 2.57). Tissue fractions at 4 versus 12 months were respectively: 31.85% ± 6.99 versus 41.32% ± 9.37 for bone (p = .021), 40.82% ± 6.71 versus 26.28% ± 11.49 for residual Mg-e HA (p = .009), and 27.33% ± 7.72 versus 32.40% ± 9.87 for medullary spaces. CONCLUSION: Data from the present study show that Mg-e HA allows the complete healing of the tissue. Additionally, graft material demonstrated to undergo significant resorption during the experimental time frame.

EMG spectral characteristics of masticatory muscles and upper trapezius during maximum voluntary teeth clenching.

To assess the surface electromyographic spectral characteristics of masticatory and neck muscles during the performance of maximum voluntary clench (MVC) tasks, 29 healthy young adults (15 men, 14 women, mean age 22years) were examined. Electromyography of masseter, temporalis and upper trapezius muscles was performed during 5-s MVCs either on cotton rolls or in intercuspal position. Using a fast Fourier transform, the median power frequency (MPF) was obtained for the first and last seconds of clench, and compared between sexes, muscles, sides, tests and time intervals using ANOVAs. On average, the MPFs did not differ between sexes or sides (p>0.05), but significant effects of muscle (MPF temporalis larger than masseter, larger than trapezius muscles), test (larger MPFs when clenching in intercuspal position than when clenching on cotton rolls) and time (larger MPFs in the first than in the fifth second of clench) were found. In conclusion, a set of data to characterize the sEMG spectral characteristics of jaw and neck muscles in young adult subjects performing MVC tasks currently in use within the dental field was obtained. Reference values may assist in the assessment of patients with alterations in the cranio-cervical-mandibular system.