Federica Musto

EMG analysis of trapezius and masticatory muscles: experimental protocol and data reproducibility

We aimed to define a standardised protocol for the electromyographic evaluation of trapezius muscle in dentistry and to assess its within- and between-session repeatability. Surface electromyography of trapezius, masseter and temporal muscles was performed in 40 healthy subjects aged 20-35 years during shoulder elevation, and maximum teeth clenching with and without cotton rolls. Two repetitions were made both within (same electrodes) and between sessions (different electrodes). Maximum voluntary clench on cotton rolls was used to standardise the potentials of the six analysed muscles with tooth contact; shoulder elevation was used to standardise the upper trapezius potentials. From the standardised electromyographic potentials, several indices (muscle symmetry; masticatory muscle torque and relative activity; total masticatory muscle activity; trapezius cervical load, percentage co-contraction of trapezius during teeth clenching) were computed; random (technical error of measurement) and systematic (Students t-test, Analysis of Variance) errors were assessed. For all indices, no systematic errors were found between the two separate data collection sessions. Within session, limited (lower than 8%) technical errors of measurement were found for temporalis and masseter symmetry, torque and activity indices, and the trapezius cervical load. Larger random errors were obtained for trapezius symmetry and total masticatory muscle activity (up to 20%). Between sessions, no significant differences were found for trapezius co-contraction. In conclusion, a protocol for the standardisation of trapezius muscle that may be used within dental clinical applications was defined, and the repeatability of masseter, temporalis and trapezius electromyographic recordings for serial assessments was assessed in healthy subjects.

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.

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.

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.

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.

Local wound healing biomarkers for real-time assessment of periodontal regeneration: pilot study

BACKGROUND AND OBJECTIVES Within the same surgical procedure, a great variability on achievement of clinical outcomes exists and may be associated to different molecular factors related to tissue healing. The aim of the present study was to assess the distribution of clinical success separately in regenerative therapy (REG) and open flap debridement (OFD) to evaluate if factors related with healing of epithelium, connective tissue and bone may be associated to the clinical outcome within each surgical procedure. MATERIAL AND METHODS Sixteen patients underwent periodontal REG and nine patients underwent OFD. Periodontal wound fluid was collected at baseline, 3-5, 7, 14 and 21 d after surgery, and expression of wound healing proteins was assessed. Pocket depth and clinical attachment level were taken at baseline and at 6 mo of follow-up. Percentage pocket depth reduction and percentage clinical attachment level gain were computed. Patients were regarded as better or worse responders depending on their percentage pocket depth reduction or percentage clinical attachment level gain. RESULTS Higher percentage of better responders was observed in the REG group (68.7%) compared to the OFD group (22.2%). At 21 d, no difference in the profile of most of the proteins emerged, with two exceptions, both regarding REG treatment. Bone morphogenetic protein-7 tended to increase in better responders and to decrease in worse responders. Matrix metalloproteinase-1 increased in worse responders and remained substantially unchanged in better responders. CONCLUSION Local expression of matrix metalloproteinase-1 and bone morphogenetic protein-7 during wound healing is associated with the clinical performance of periodontal regenerative surgery. The use of local biomarkers offers the potential for real-time assessment of the periodontal healing process.

Histological and clinical analysis of fresh-frozen allogeneic vs autogenic bone grafts for 3D alveolar bone reconstruction

Reconstruction of atrophic alveolar bone can be made with many grafting materi- als. Autogenous bone, from intra- or extraoral donor sites, represents the best doc- umented material in terms of number of patients and follow-up; allogeneic freshfrozen bone (FFB), from dead bodies has been suggested as an alternative to overcome problems related to autogenous bone collection (1, 2). The aim of this work is to histologically and histomorphometrically compare bone biopsies obtained during dental implant placement in reconstructed jaws with either FFB or autologous iliac crest bone blocks using the same surgical grafting procedure. All samples were processed for ground sections and then underwent a histomorphometrical evaluation using a stereologic method. Twenty edentulous patients were treated with either FFB (14 patients, group A) or with autografts (6 patients, group B) iliac crest grafts. Five to 9 months later, dental implants were placed in the reconstructed jaws and bone biopsies were harvested. Reconstructive procedure was uneventful in 9 patients of group A and in all patients of group B. In 5 patients of group A, bone sequestra were obtained and processed for ground sections. These specimens showed the typical findings of a bone necrosis. All other samples from both groups presented the same values in terms of proportion of lamellar, newly formed bone and bone marrow. In group A, the decreasing proportion of blood vessels from apical to coronal, the larger amount of osteocytic lacunae in the apical portion and the fewer vessels in the coro- nal portion compared to group B, evoke an effort of the host bone to “integrate” the graft from the apical portion. FFB cannot be considered as successful and safe in alve olar bone reconstruction as autogenous bone grafting.

Immunohistochemical and molecular analysis of bone remodelling pattern in alveolar socket

Following tooth extraction, the alveolar bone remodelling process starts. Bundle bone and buccal wall resorption occur early with horizontal and vertical bone crest reduction [1]. The use of bone substitutes has been proposed to limit bone resorption, thus allowing further dental rehabilitation [2]. Aim of this project was to characterize by a molecular and morphological approach the physiological remodelling of post-extractive alveolar socket and to compare it with the bone remodelling occurring after alveolar bone reconstruction with an alloplastic material. Thirty-six patients needing tooth extraction were enrolled and equally divided into three groups: A) baseline, B) spontaneous healing, C) biomaterial. In each group, 2 biopsies per site were harvested during tooth extraction (group A) or 4-6 months after tooth extraction (groups B and C). In group B, patients recovered spontaneously, while in group C the alveolar socket was filled with a magnesium-enriched hydroxyapatite. One biopsy was processed for immunohistochemistry to localise TNF-α, IL-6, RANK, RANKL and OPG. The second biopsy underwent a Real-Time PCR analysis for the same biomarkers in order to evaluate gene expression. In groups B and C, a third biopsy was retrieved and processed for ground section aiming to assess tissue composition. Differences between the three groups were investigated using Kruskal Wallis test (p<0,05) followed by post-hoc tests. All samples showed a normal structure without inflammatory infiltrate. At immunohistochemical analysis, all biomarkers except for OPG had increased. Significant differences were found between the three groups for TNF-α (p< 0,05), IL-6 (p<0,001), RANK (p< 0,01) and RANKL (p<0,001), between groups A and C for IL-6 (p≤ 0,001), RANK (p≤ 0,01), RANKL (p≤ 0,001) and between B and C for IL-6 (p≤ 0,01). Gene expression did not show statistical differences. Crumbles of biomaterial surrounded by regenerated bone were evident. A higher percentage of mineral component was obtained in group B than in C. The biomarkers selected in the current study were involved in the alveolar remodelling and the biomaterial used for socket preservation did not influence the process.

Guida alla scelta di un biomateriale per la preservazione alveolare: l’importanza dei fattori biologici di rimodellamento

Riassunto Obiettivi Descrivere i principali fattori di crescita e di differenziazione che intervengono nei processi di guarigione alveolare e analizzare le dinamiche biologiche che sono alla base dell’integrazione di un sostituto osseo. Il dossier prevede inoltre una sezione clinica esplicativa, nella quale vengono esaminati due diversi modelli di sperimentazione clinica nell’intento di documentare, in vivo, l’influenza dei materiali d’innesto sul pattern di rimodellamento osseo in un sito post-estrattivo. Materiali e metodi Per reperire materiale sull’argomento sono stati consultati testi di odontoiatria e chirurgia odontostomatologica, e banche dati scientifiche. Risultati e conclusioni Negli ultimi anni, le metodiche di preservazione alveolare basate sull’impiego di differenti innesti ossei “bone graft”, tra cui i biomateriali sintetici “alloplast”, hanno riscosso ampio successo in chirurgia odontoiatrica. I materiali riempitivi sintetici, infatti, grazie alla loro biocompatibilita e alla loro azione osteoconduttiva, trovano applicazione al fine di favorire la guarigione alveolare e preservare il volume, l’ampiezza e l’altezza della cresta edentula. Se da un lato appare chiaro il pattern di rimodellamento fisiologico a carico dell’alveolo in seguito alla perdita di un dente, dall’altro risulta poco comprensibile l’influenza di tali biomateriali a carico dei meccanismi di segnale coinvolti nel processo di rimodellamento nel sito d’innesto. La metodica immunoistochimica si rivela uno strumento molto utile nella valutazione, in vivo, degli effetti che diversi biomateriali determinano sul rimodellamento alveolare.