Altered mastication adversely impacts morpho-functional features of the hippocampus: A systematic review on animal studies in three different experimental conditions involving the masticatory function.

Recent results have established that masticatory function plays a role not only in the balance of the stomatognathic system and in the central motor control, but also in the trophism of the hippocampus and in the cognitive activity. These implications have been shown in clinical studies and in animal researches as well, by means of histological, biochemical and behavioural techniques. This systematic review describes the effects of three forms of experimentally altered mastication, namely soft-diet feeding, molar extraction and bite-raising, on the trophism and function of the hippocampus in animal models. Through a systematic search of PubMed, Embase, Web of Science, Scopus, OpenGray and GrayMatters, 645 articles were identified, 33 full text articles were assessed for eligibility and 28 articles were included in the review process. The comprehensiveness of reporting was evaluated with the ARRIVE guidelines and the risk of bias with the SYRCLE RoB tool. The literature reviewed agrees that a disturbed mastication is significantly associated with a reduced number of hippocampal pyramidal neurons in Cornu Ammonis (CA)1 and CA3, downregulation of Brain Derived Neurotrophic Factor (BDNF), reduced synaptic activity, reduced neurogenesis in the Dentate Gyrus (DG), glial proliferation, and reduced performances in behavioural tests, indicating memory impairment and reduced spatial orientation. Moreover, while the bite-raised condition, characterized by occlusal instability, is known to be a source of stress, soft-diet feeding and molar extractions were not consistently associated with a stress response. More research is needed to clarify this topic. The emerging role of chewing in the preservation of hippocampal trophism, neurogenesis and synaptic activity is worthy of interest and may contribute to the study of neurodegenerative diseases in new and potentially relevant ways.

Condylar long axis and articular eminence in MRI in patients with temporomandibular disorders.

OBJECTIVE: To compare morphologic findings in MRI and skeletal divergence of a group of patients with temporomandibular joint disorders (TMD) subdivided into condylar symmetric and asymmetric. METHODS: Fifty-nine adults (26.7 years old) with TMD were retrospectively recruited. Condylar height symmetry was evaluated by orthopantomography (Habets's method) and used to divide patients into Symmetric and Asymmetric groups; skeletal divergence was assessed on lateral cephalograms. MRI was used to evaluate the condylar long axis' angle, the glenoid fossa morphology, and the degree of disc displacement. RESULTS: Asymmetric subjects showed a hyperdivergent skeletal pattern (p = 0.036), asymmetric condylar long axis (p = 0.018), and deeper (p = 0.025) and asymmetric (p = 0.001) glenoid fossa compared to symmetric subjects. CONCLUSION: Patients with TMD and condylar asymmetry diagnosed with orthopantomography are more likely to show hyperdivergent skull in cephalometry, condylar asymmetry of both height and major axis, and a steeper glenoid fossa in MRI.

Fem and Von Mises Analysis of OSSTEM ® Dental Implant Structural Components: Evaluation of Different Direction Dynamic Loads.

PURPOSE: The objective of this investigation is to study prosthodontics and internal components resistance to the masticatory stress and considering different force directions by using Finite Element Method analysis (FEM). The structural materials of the components are usually Titanium alloy grade 4 or 5 and thus, guarantee the integration of the fixture in the bone due to the osteointegration phenomena. Even if the long-term dental implant survival rate is easy to be obtained and confirmed by numerous researches, the related clinical success, due to the alteration of the mechanical and prosthodontics components is still controversial. METHODS: By applying engineering systems of investigations like FEM and Von Mises analyses, it has been investigated how dental implant material was held against the masticatory strength during the dynamic masticatory cycles. A three-dimensional system involved fixture, abutment and the connection screws, which were created and analyzed. The elastic features of the materials used in the study were taken from recent literature data. RESULTS: Data revealed a different response for both types of devices, although implant neck and dental abutment showed better results for all conditions of loading while the abutment screw represented aweak point of the system. CONCLUSION: The data of this virtual model showed all the features of different prosthetic retention systems under the masticatory load. Clinicians should find better prosthetic balance in order to better distribute the stress over the component and to guarantee patients' clinical long-term results.

Postextraction Dental Implant in the Aesthetic Zone, Socket Shield Technique Versus Conventional Protocol.

The aim of this randomized controlled trial was to evaluate the survival rate, the marginal bone level, and the aesthetic outcome; at 3 years' follow-up, of dental implants placed into a high-esthetic aesthetic zone by comparing 2 techniques of postextraction implant with immediate loading: the socket shied technique and the conventional insertion technique.Several clinical studies suggested that the avulsion of a dental element causes dimensional alterations of both soft and hard tissues at the postextractive site. To increase the aesthetic outcomes, the "socket-shield technique" has been proposed. This method involves maintaining the vestibular root portion and immediate insertion of the dental implant in close proximity to the root.Patients enrolled in this study were randomized to receive a postextraction implant in the aesthetic zone, either with the socket shied technique or with the conventional insertion technique. Implant survival, marginal bone level, and the pink aesthetic score were the outcomes evaluated.Implant survival rate was 100% in both the groups at 3 years. Implants inserted with the socket shield technique showed better values of both marginal bone level and pink aesthetic score (P < 0.05).Although such preliminary results need to be further confirmed, the socket shield technique seems to be a safe surgical technique that allows an implant rehabilitation characterized by better aesthetic outcomes.

Facial Bone Reconstruction Using both Marine or Non-Marine Bone Substitutes: Evaluation of Current Outcomes in a Systematic Literature Review.

The aim of the present investigation was to systematically analyse the literature on the facial bone reconstruction defect using marine collagen or not and to evaluate a predictable treatment for their clinical management. The revision has been performed by searched MEDLINE and EMBASE databases from 2007 to 2017. Clinical trials and animal in vitro studies that had reported the application of bone substitutes or not for bone reconstruction defect and using marine collagen or other bone substitute material were recorded following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The first selection involved 1201 citations. After screening and evaluation of suitability, 39 articles were added at the revision process. Numerous discrepancies among the papers about bone defects morphology, surgical protocols, and selection of biomaterials were found. All selected manuscripts considered the final clinical success after the facial bone reconstruction applying bone substitutes. However, the scientific evidence regarding the vantage of the appliance of a biomaterial versus autologous bone still remains debated. Marine collagen seems to favor the dimensional stability of the graft and it could be an excellent carrier for growth factors.

Facial and Orbital Fractures: A Fifteen Years Retrospective Evaluation of North East Sicily Treated Patients.

BACKGROUND: Orbital fractures are classified as diseases usually related to common midface trauma. It represents the most challenging treatment due to the complex anatomy, physiology, and aesthetic role. A midface trauma involves also the zygomatic complex and the nose, however the orbit fracture seems to be a more frequent disease due to its anatomical features. OBJECTIVE: The purpose of this work is to retrospectively evaluate and record the frequency of the midfacial traumas and orbital fractures observed in the North Eastern Sicily. The results of the present data may be useful for the clinicians in order to recognize the kind of fracture just from the first general visit having a quick diagnosis and management. METHODS: In the years between 2001 and 2016, about 1200 patients with midfacial trauma and about 100 patients involving the orbital floor have been evaluated. All those patients underwent the surgical fracture reduction and a CT scan follow up control at one month, three months, six months and one year. RESULTS: Data showed high percentage of orbital floor, nose and mandibular body and ramus fractures; moreover the most frequent causes of fractures seem to be related to motor vehicle accident, followed by assaults, work and fall. CONCLUSION: The results have highlighted the changing trends in the causes of facial injuries, particularly the increasing incidence of assaults and the falling incidence of motor vehicle accidents in developed countries. The quick diagnosis and management proved fundamental for the successful treatment. Clinicians should be able to recognize the first symptoms in order to avoid possible complications.

Oral Behaviors and Parafunctions: Comparison of Temporomandibular Dysfunction Patients and Controls.

The aim of this study is to evaluate the frequency of oral behaviors in patients with temporomandibular disorders (TMD) and a control group without TMD.In this baseline case-control study, 260 controls and 260 subjects with TMD completed the oral behaviors checklist defined as a "self-report scale for identifying and quantifying the frequency of jaw overuse behavior" and underwent clinical examinations using the DC/TMJ international examination form (version May 12, 2013). Relationships of oral parafunctions' frequencies between groups were examined. The statistical analysis was performed with IBM SPSS Statistics 23 software.Age and gender distribution in the study groups did not reveal statistical differences (P > 0.05). Multivariate logistic regression analysis was conducted to establish system of independent oral behaviors for prognosis TMD. The stepwise regression analysis demonstrated that very frequent expression of holding, tightening, or tense muscles is associated with 10.83 times (P < 0.05) higher risk of TMD, grinding teeth together during waking hours with 4.94 times (P < 0.05) higher risk, and sustained talking with 2.64 times (P < 0.05) higher risk of TMD. By contrast, it was determined that 3 oral behaviors were less common in the TMD patients compared with the control group: clenching teeth together during waking hours, facing grimaces, and yawning (P < 0.05). The individuals with TMD reported a significantly higher frequency of 10 behaviors (P < 0.05), 3 of which may be regarded as independent risk factors for TMD. In addition, 3 oral behaviors were more frequently observed in the healthy subjects than in the TMD patients.

FEM and Von Mises Analysis on Prosthetic Crowns Structural Elements: Evaluation of Different Applied Materials.

The aim of this paper is to underline the mechanical properties of dental single crown prosthodontics materials in order to differentiate the possibility of using each material for typical clinical condition and masticatory load. Objective of the investigation is to highlight the stress distribution over different common dental crowns by using computer-aided design software and a three-dimensional virtual model. By using engineering systems of analyses like FEM and Von Mises investigations it has been highlighted the strength over simulated lower first premolar crowns made by chrome cobalt alloy, golden alloy, dental resin, and zirconia. The prosthodontics crown models have been created and put on simulated chewing stresses. The three-dimensional models were subjected to axial and oblique forces and both guaranteed expected results over simulated masticatory cycle. Dental resin presented the low value of fracture while high values have been recorded for the metal alloy and zirconia. Clinicians should choose the better prosthetic solution for the teeth they want to restore and replace. Both prosthetic dental crowns offer long-term success if applied following the manufacture guide limitations and suggestions.

Interface Between MTA and Dental Bonding Agents: Scanning Electron Microscope Evaluation.

AIMS AND OBJECTIVES: Nowadays, the material that offers the best sealing characteristic in the field of endodontic treatment is the mineral trioxide aggregate (MTA), nevertheless, this material necessities an adhesive bonding agent to perfectly join to the dental surface. The aim of this study was to analyze using a scanning electron microscope (SEM) the possible microgap between the adhesive, MTA, and the dental surface. MATERIAL AND METHODS: Fourteen extracted molars were divided into two groups - group A was prepared with MTA-component adhesive and group B was prepared with MTA and composite dual etching. The observations were carried out with a SEM Phenom G2 Pro mode S.E.I. JMP® software was used for statistical analysis, and a t-test was used for evaluating the difference between the two groups. RESULTS: The gap of the areas at higher magnification (1000×) with a size greater than 5 microns in width and 20 microns in length were considered significant, and only group A recorded significant data. CONCLUSIONS: The SEM analysis performed in the group A with interposition of adhesive and flow between the dental pulp chamber and MTA demonstrates the presence of a marginal gap of considerable amplitude in the all of the samples investigated.

Histomorhological and clinical evaluation of maxillary alveolar ridge reconstruction after craniofacial trauma by applying combination of allogeneic and autogenous bone graft.

A variety of techniques and materials for the rehabilitation and reconstruction of traumatized maxillary ridges prior to dental implants placement have been described in literature. Autogenous bone grafting is considered ideal by many researchers and it still remains the most predictable and documented method. The aim of this report is to underline the effectiveness of using allogeneic bone graft for managing maxillofacial trauma. A case of a 30-year-old male with severely atrophic maxillary ridge as a consequence of complex craniofacial injury is presented here. Augmentation procedure in two stages was performed using allogeneic and autogenous bone grafts in different areas of the osseous defect. Four months after grafting, during the implants placement surgery, samples of both sectors were withdrawn and submitted to histological evaluation. On the examination of the specimens, treated by hematoxylin and eosin staining, the morphology of integrated allogeneic bone grafts was revealed to be similar to the autologous bone. Our clinical experience shows how the allogeneic bone graft presented normal bone tissue architecture and is highly vascularized, and it can be used for reconstruction of severe trauma of the maxilla.

Dental implant positioning by using the root way. A predictable technique for postextractive surgery.

BACKGROUND: Postextractive dental implant surgery is a technique characterized by several advantages like placing the implant during the same moment of the extraction, so reducing the time of the surgery and consequently all the prosthetic procedure; however some limitations still remain during this procedure. The disadvantages are represented by the unpredictable results of the healing of the extraction socket, its bone resorption and the dental implant inclination even using a prosthetic guide. Aim of this study is to present a predictable technique for having better aesthetic and functional results during the dental implant positioning. METHODS: This study want to presents clinical and radiological case report of dental implant placed following the line of the root before the extraction, in order to share with the clinicians a surgical experience that results to be simple and predictable. RESULTS: The implants placed with this kind of technique showed successful osseointegration after an uneventful healing period of two years. CONCLUSIONS: The described technique allows the clinician to achieve the ideal implant positioning during immediate implant placement at multirooted extraction sites.

Three-dimensional evaluation of different prosthesis retention systems using finite element analysis and the Von Mises stress test.

BACKGROUND: The aim of this paper is to underline the prosthodontics components features of two different overdenture retention systems on dental implants. The use of titanium, dental implants for replacing missing teeth is today considered to be a predictable procedure giving the patients esthetic and function for long time. METHODS: Finite element analysis (FEA) and tests based on the Von Mises criterion have been applied in order to evaluate the stress distribution over two different prosthodontics retention systems. Two models with the ball attachment and with the Locator® systems have been created and put on simulated chewing stresses. RESULTS: The two systems were subjected to axial and oblique forces and both guaranteed good results over simulated masticatory cycle. However, the Locator system seemed to better respond to the overall load distributions. CONCLUSIONS: Clinicians should choose the better prosthetic solution for the ridge they want to restore. Both retention systems offer long-term success if applied following the manufacture guide limitations and suggestions.

Pattern of nodal involvement in papillary thyroid cancer: a challenge of quantitative analysis.

INTRODUCTION: Backgrounds of this study were to examine and analyse the relationship among the number of lymph nodes with metastases harvested in central and lateral compartments, the characteristics of tumours and patients, and the recurrences rate. METHODS: A retrospective review of 118 patients treated for a papillary thyroid cancer and underwent to neck dissection, including in all cases both central and lateral compartment, was realised. A quantitative analysis, on this homogeneous cohort of patients, was performed to hypothesize the minimum number of cervical lymph nodes to be necessarily excised in order to obtain an adequate management of these patients. RESULTS: The mean follow-up time was 75.9 months. Five-year overall survival was 96.6%. The correlation among the metastatic lymph node number of the ipsilateral central compartment, isolated or pooled with those of the ipsilateral lateral compartment, age of patient and tumour size revealed a statistical significance (P=0.01); both parameters, tumour size and age, may be considered as dependent predictor variables. CONCLUSION: We suppose, notwithstanding the limited number of patients, that the number of lymph nodes harvested to achieve an optimal cervical dissection may be superior to 8 and 11 in central and lateral compartments, and 6 and 10 in contralateral ones, respectively. Moreover we recommend the bilateral dissection of central nodes compartment in presence of tumour localised in the isthmus.

Dentin Morphology of Root Canal Surface: A Quantitative Evaluation Based on a Scanning Electronic Microscopy Study.

Dentin is a vital, hydrated composite tissue with structural components and properties that vary in the different topographic portions of the teeth. These variations have a significant implication for biomechanical teeth properties and for the adhesive systems utilized in conservative dentistry. The aim of this study is to analyse the root canal dentin going from coronal to apical zone to find the ratio between the intertubular dentin area and the surface occupied by dentin tubules varies. Observations were conducted on 30 healthy premolar teeth extracted for orthodontic reasons in patients aged between 10 and 14. A SEM analysis of the data obtained in different canal portions showed that, in the coronal zone, dentinal tubules had a greater diameter (4.32 µm) than the middle zone (3.74 µm) and the apical zone (1.73 µm). The average number of dentinal tubules (in an area of 1 mm(2)) was similar in coronal zone (46,798 ± 10,644) and apical zone (45,192 ± 10,888), while in the middle zone they were lower in number (30,940 ± 7,651). However, intertubular dentin area was bigger going from apical to coronal portion. The differences between the analysed areas must be considered for the choice of the adhesive system.

Guillain-Barré syndrome: report of two rare clinical cases occurring after allergenic bone grafting in oral maxillofacial surgery.

Guillaine-Barré Syndrome (GBS), also known as post-infectious polyneuropathy or acute idiopathic polyneuritis, is an infrequent disorder of the peripheral nervous system. The cause of GBS is unknown. It has been associated in the past with microbial infections, vaccinations, surgical procedures and debilitation of the patient. The classic signs of GBS occurring in the two patients being reported here are muscle weakness, motor and sensory impairment and ascending paralysis with respiratory involvement. The documented cases involved GBS syndrome following oral and maxillofacial surgery in which allogeneic-banked freeze-dried bone have been utilized along with autogenous grafting. There were no incidents of viral infection, vaccination or the other prodromal incidents involved in these cases. It is believed that the description of these two cases would be of interest in that it may stimulate the reporting of similar anecdotal occurrences by other surgeons. Both patients fully recovered from the GBS and are presently alive and well.

Platelet-derived growth factor type BB and collagen matrix for soft tissue reconstruction after muco-epidermoid carcinoma removal: a possible therapeutic option.

Muco-epidermoid carcinoma (MEC) is a rare malignant tumor occurring in major and minor salivary glands. The described case shows a patient undergoing tumor resection without neck dissection. A quick diagnosis performed through clinical investigation and incisional biopsy revealed the nature of the tumor. A porcine collagen matrix was applied after the surgery in order to improve soft tissue healing. The matrix was saturated with platelet-derived growth factor type BB in order to favorite healing process and then fixed on the palate with a dental support device. Follow-up visit performed at first, second, and third weeks highlighted a quick healing of oral mucosa. Here reported is a case of a 34-year-old man who developed a muco-epidermoid oral carcinoma localized in the left upper jaw palatal side. The clinical, radiographic, and histopathologic findings, plus differential diagnoses of the case and reconstructive treatment options are also presented.

Autogenous wisdom tooth transplantation: A case series with 6-9 months follow-up.

Tooth transplantation can be considered a valid and predictable treatment option for rehabilitating young patients with permanent teeth loss. This study presents several cases of successful autogenous tooth transplantation with a 6-9 months follow-up. Tooth auto-transplantation can be considered a reasonable option for replacing missing teeth when a donor tooth is available. The auto-transplantation of a right mandibular third molar with compromised function and esthetics to replace the residual roots resulting from coronal destruction due to extensive carious lesion of the second molar in the same quadrant as shown in the presented cases can result a viable treatment alternative especially in a young patient that cannot undergo dental implant therapy. Transplantation of mature third molar seems to be a promising method for replacing a lost permanent molar tooth and restoring esthetics and function. This clinical procedure showed excellent functional and esthetical long-term results in the analyzed cases.

Clinical Evaluation of Specific Oral Manifestations in Pediatric Patients with Ascertained versus Potential Coeliac Disease: A Cross-Sectional Study.

Patients involved on coeliac disease (CD) have atypical symptoms and often remain undiagnosed. Specific oral manifestations are effective risk indicators of CD and for this reason an early diagnosis with a consequent better prognosis can be performed by the dentist. There are not researches analysing the frequency of these oral manifestations in potential coeliac patients. The aim of this study is to investigate the oral hard and soft tissue lesions in potential and ascertained coeliac children in comparison with healthy controls. 50 ascertained children, 21 potential coeliac patients, and 54 controls were recruited and the oral examination was performed. The overall oral lesions were more frequently present in CD patients than in controls. The prevalence of oral soft tissue lesions was 62% in ascertained coeliac, 76.2% in potential coeliac patients, and 12.96% in controls (P < 0.05). Clinical dental delayed eruption was observed in 38% of the ascertained coeliac and 42.5% of the potential coeliac versus 11.11% of the controls (P < 0.05). The prevalence of specific enamel defects (SED) was 48% in ascertained coeliac and 19% in potential coeliac versus 0% in controls (P < 0.05; OR = 3.923). The SED seem to be genetically related to the histological damage and villous atrophy.

FEM evaluation of cemented-retained versus screw-retained dental implant single-tooth crown prosthesis.

Prosthetic rehabilitation of partial or total edentulous patients is today a challenge for clinicians and dental practitioners. The application of dental implants in order to recover areas of missing teeth is going to be a predictable technique, however some important points about the implant angulation, the stress distribution over the bone tissue and prosthetic components should be well investigated for having final long term clinical results. Two different system of the prosthesis fixation are commonly used. The screw retained crown and the cemented retained one. All of the two restoration techniques give to the clinicians several advantages and some disadvantages. Aim of this work is to evaluate all the mechanical features of each system, through engineering systems of investigations like FEM and Von Mises analyses. The FEM is today a useful tool for the prediction of stress effect upon material and biomaterial under load or strengths. Specifically three different area has been evaluated through this study: the dental crown with the bone interface; the passant screw connection area; the occlusal surface of the two different type of crown. The elastic features of the materials used in the study have been taken from recent literature data. Results revealed an adequate response for both type of prostheses, although cemented retained one showed better results over the occlusal area.

Analysis of the characteristics of slot design affecting resistance to sliding during active archwire configurations.

BACKGROUND: During orthodontic treatment, a low resistance to slide (RS) is desirable when sliding mechanics are used. Many studies showed that several variables affect the RS at the bracket-wire interface; among these, the design of the bracket slot has not been deeply investigated yet. This study aimed to clarify the effect of different slot designs on the RS expressed by five types of low-friction brackets in vertical and horizontal active configurations of the wire. METHODS: Five low-friction brackets (Damon SL II, Ormco, Orange, CA, USA; In-Ovation, GAC International, Bohemia, NY, USA; Quick, Forestadent, Pforzheim, Germany; Time 2, AO, Sheboygan, WI, USA; Synergy, RMO, Denver, CO, USA) coupled with an 0.014-in NiTi thermal wire (Therma-Lite, AO) were tested in two three-bracket experimental models simulating vertical and horizontal bracket displacements. A custom-made machine was used to measure frictional resistance with tests repeated on ten occasions for each bracket-wire combination. Design characteristics such as the mesio-distal slot width, slot depth, and presence of chamfered edges at the extremities of the slot were evaluated on SEM images (SUPRA, Carl Zeiss, Oberkochen, Germany) and analyzed in relation to the data of RS recorded. RESULTS: Time 2 was found to show the higher frictional forces (1.50 and 1.35 N) in both experimental models (p<0.05), while Quick and Synergy brackets showed the lower frictional values in the vertical (0.66 N) and in the horizontal (0.68 N) bracket displacements, respectively. With vertically displaced brackets, the increased mesio-distal slot width and the presence of clear angle at mesial and distal slot edges increase the values of RS. With brackets horizontally displaced, the RS expressed by the wire is influenced simultaneously by the depth of the slot, the mesio-distal slot width, and the presence of clear angle at the extremities of the slot base, the clip, or the slide. CONCLUSION: In order to select the proper low-friction bracket system, clinicians should consider specific characteristics of slot design apart from the wire engaging method.