Stress-strain and fatigue life numerical evaluation of two different dental implants considering isotropic and anisotropic human jaw.

Dental prostheses are currently a valid solution for replacing potential missing tooth or edentulism clinical condition. Nevertheless, the oral cavity is a dynamic and complex system: occlusal loads, external agents, or other unpleasant events can impact on implants functionality and stability causing a future revision surgery. One of the failure origins is certainly the dynamic loading originated from daily oral activities like eating, chewing, and so on. The aim of this paper was to evaluate, by a numerical analysis based on Finite Elements Method (FEM), and to discuss in a comparative way, firstly, the stress-strain of two different adopted dental implants and, subsequently, their fatigue life according to common standard of calculations. For this investigation, the jawbone was modeled accounting for either isotropic or anisotropic behavior. It was composed of cortical and cancellous regions, considering it completely osseointegrated with the implants. The impact of implants' fixture design, loading conditions, and their effect on the mandible bone was finally investigated, on the basis of the achieved numerical results. Lastly, the life cycle of the investigated implants was estimated according to the well-established theories of Goodman, Soderberg, and Gerber by exploiting the outcomes obtained by the numerical simulations, providing interesting conclusions useful in the dental practice.

Adherence to Antibiotic Prescription of Dental Patients: The Other Side of the Antimicrobial Resistance.

Since non-adherence to antibiotic therapy can cause several problems, including antimicrobial resistance (AMR) and treatment failures, the present study evaluated adherence to oral antibiotic therapy and AMR awareness among consecutively enrolled dental patients. Data concerning age, gender, socioeconomic status, education level, cohabitation, and general health were retrieved from medical records. AMR awareness was investigated through direct questions and adherence to antibiotic treatment was assessed through a modified Italian version of the Morisky medical scale-8 items. Participants' characteristics were analyzed in relation to treatment adherence and AMR, using a Χ2 independence test (significance level of α <0.1). Dental patients generally showed a low (51.82%) adherence to oral antibiotic therapy, and medium and high adherence was reported only by 29.37% and 18.81% of participants. Treatment adherence was similar in relation to participants' gender and age but significantly lower in subjects with only secondary school graduation and higher in participants with higher education levels. Non-cohabitants were significantly more adherent than cohabitants. AMR awareness was declared by 42.15% of males and 38.70% of females: 56.52% of dental patients aware of AMR were 18−38 years old, 35.20% were 39−59 years old, and 26.95% were aged between 60 and 80. Further studies are needed to develop adequate strategies, expanding dental patients' knowledge of AMR, thus optimizing the benefits and reducing the risks of antibiotic administration in dental patients.

Periodontal and Peri-Implant Diseases and Systemically Administered Statins: A Systematic Review.

Hyperlipidemia is a well-recognized risk factor for cardiovascular disease, which, in turn, acts as a contributory factor in periodontitis development. Periodontitis has been associated with benign tumors and cancers and withseveral disorders, including hyperlipidemia. Correspondingly, periodontal treatment may exert a positive effect on lipid metabolism, although opposite evidence has also been reported. As a counterpart, the therapy for hyperlipidemia, conventionally based on statins, has been proposed to positively affect periodontal conditions, mainly due to statin pleiotropic effects, reducing periodontal inflammation and promoting osseointegration. Therefore, the present systematic review aimed to evaluate, in subjects with untreated periodontitis and peri-implant disease (Population), the effect of routine systemically administered statins (Intervention), compared to non-statin use (Comparison), on periodontal parameters around natural teeth and implants (Outcome). Discordant results were found in periodontal parameters, and the current lack of such data related to peri-implant tissues and to alveolar bone loss highlights the need for further studies on the topic, potentially paving the way for a more comprehensive approach to periodontitis and peri-implantitis management. Indeed, the validation of the beneficial effect provided by systemically delivered statins on periodontal and peri-implant tissues may direct recall scheduling, predict response to therapy and, therefore, guide treatment strategies of periodontal and peri-implant treatments in statin users.

Oral Healthcare and Idiopathic Thrombocytopenic Purpura: Early Recognition, Dental Management and Case Report.

A 47-year-old Caucasian man, in good general, oral and periodontal health, presented with a non-bleeding bluish lesion on the back of his tongue, presumably due to an ecchymotic area of traumatic origin which was left untreated. The day after, other ecchymotic-type lesions on the mucous membranes of the cheeks and the upper lip, a bleeding lesion at the apex of the tongue and gingivorrhagia, along with petechiae on the back, scalp, lower limbs and feet, occurred, with rapid clinical deterioration, requiring immediate hospitalization. Oral, dermatological, and hematological evaluations lead to idiopathic thrombocytopenic purpura (ITP) diagnosis and hydrocortisone prescription, with a complete recovery in the next few days.The presented case of ITP, with early intra-oral manifestations, aimed both to emphasize the role of oral healthcare workers in theearly recognition of ITP, which may be especially relevant for those cases with extremely fast platelet depletion, high risk of internal bleeding and consequent potentially fatal complications, and in the differential diagnosis of the diseasethat may be aided by the diagnostic protocol described, and to provide dentists with recommendations on oral care management of cases of ITP, both in dental and multi-disciplinary settings.

Experimental Comparison on Dental BioTribological Pairs Zirconia/Zirconia and Zirconia/Natural Tooth by Using a Reciprocating Tribometer.

The application of tribology in dentistry is growing rapidly, intense research has been conducted to develop an understanding of dental tribology for better selection of artificial materials and dental implant design. Dental biotribology, has been one of the most important branches in biotribology in recent years. The aim of this research is to investigate the tribological performances in the tooth-to-tooth contact and material-to-natural tooth contact (zirconia vs. zirconia and natural tooth vs. zirconia). The presented research was carried out by testing the above mentioned tribological pairs with the use of a reciprocating tribometer under lubricated conditions (artificial saliva). The normal force used in the tests was 20 N the time for each test was of 60 min. The stroke length was 2 mm, according to the range of displacement used in scientific literature. The wear mass loss evaluation was evaluated by using a gravimetric method. In order to characterize the wear mechanisms, present in the worn surfaces after each of tribo-tests, a topographic analysis was carried with a 3D non-contact optical profiler. The results show that the minimum value of the COF is obtained in the case of Zirconia vs. Zirconia tribo-couple. The results on the wear mass loss show a very low wear rate when coupling in tribological condition natural tooth with a ceramic restoration (a mean value of 0.5 mg was found). This rate is even lower when the contact is between two artificial zirconia teeth.

Effects of repeated cycles of sterilisation on the mechanical characteristics of titanium miniplates for osteosynthesis.

AIM: This study investigates the changes occurring in the mechanical characteristics of osteosynthesis titanium miniplates when exposed to repeated sterilization cycles. METHODS: For this study Medicon (c) titanium miniplates were used. The characteristics of miniplates were evaluated using the Penetration Resistance test, MSC/Pal2 Software, and the Finite Elements Method (F.E.M.). Surface roughness measurements were also carried out. Statistical analysis was conducted using the One way ANOVA model. The significance level was set at >0.05. RESULTS: The one way ANOVA analysis between HV value and increased sterilization cycles showed P>0.029; between the Ra value and increased sterilization cycles it was P>0.325; between the Rq value and increased sterilization cycles it was P>0.703. The Finite Element Model shows an amplified deformed shape of the miniplate at a load of 196 [N]. At this load value the equivalent 'von Mises stress' reaches the value of sigmaP0.2, shown by the ASTM F 67-95 standard. Stress distribution comparison between the six-holed plate and the equivalent straight miniplate shows more consistent behaviour for the Medicon (c) miniplate. The rigidity of the Medicon (c) miniplate is 14.46, lower than that for the equivalent straight miniplate (R=23.4). The ANOVA analysis between the break load and increased sterilization cycles showed P>0.175; between the break position and increased sterilization cycles it showed P>0.016. CONCLUSIONS: Experimental static tests have shown that all tested miniplates did not have notable differences and this suggests that sterilization cycles do not affect mechanical characteristics.

Neurosensory disturbance of the inferior alveolar nerve after bilateral sagittal split osteotomy: a systematic review.

PURPOSE: The evaluation of neurosensory disturbance of the inferior alveolar nerve (IAN) can be performed by purely subjective, relatively objective, or purely objective methods. The aim of this study was to provide a systematic review of the incidence of inferior alveolar nerve sensory disturbance after bilateral sagittal split osteotomy, as well as the frequency of recovery of sensory function using objective methods of evaluation only. MATERIALS AND METHODS: Searches were conducted employing MEDLINE, Scirus, and the Cochrane Central Register of Controlled Trials (CENTRAL). Seven studies were included in this review. RESULTS: This systematic review has shown that the frequency of nerve impairment evaluated by subjective methods was higher than that indicated by studies adopting objective methods at each time of follow-up considered. In particular at the seventh postoperative day the frequency obtained using the objective methods was 63.3% while that obtained with subjective methods was 83%. At 1 year follow-up a frequency of sensory impairment of 12.8% was obtained using objective methods and a frequency of 18.4% when subjective methods were used. The data were analysed using the index of inter-rater reliability (Cohen's Kappa) with the degree of nerve damage evaluated by objective methods considered the "gold standard." The value of Cohen's Kappa at 1 week follow-up is 0.53; at 1 year follow-up it increased to 0.90. CONCLUSIONS: On the basis of these results, objective methods provide the most sensitive diagnostic tests at early controls-within 3 months of the operation. At later control points the sensitivity increases and the inter-rater reliability is satisfactory.

Expression of four histone lysine-methyltransferases in parotid gland tumors.

Methylation of histones is one of the important "epigenetic" mechanisms associated with the transcriptional silencing and/or activating of tumor suppressor genes. To assess whether epigenetic phenomena could be involved in salivary gland carcinogenesis, the expression levels of four histone lysine-methyltransferases (HMT) were investigated, in both pleomorphic adenoma and the adjacent normal tissue of the parotid glands. The expression levels of three HMTs, SETB1, Eu-HMTase and SET08, were higher in tumor tissues. On the contrary, DOTL1 presented a lower expression level in the tumor tissues than in the corresponding normal tissues. These data suggest that the HMTs may be involved in the differentiation of pleomorphic adenoma, probably through chromatin structural changes, and indicates that the study of the epigenetic mechanism which modulates the variation in the methylation profile of histones may be useful to obtain information concerning those genes involved in tumor transformation in human parotid glands.

Giant infiltrating lipoma of the face: CT and MR imaging findings.

Infiltrating lipoma is an uncommon mesenchymal neoplasm that characteristically infiltrates adjacent tissues and tends to recur after excision. This type of lipoma is extremely rare in the head and neck region. We report a case of a giant infiltrating lipoma of the face, studied with CT and MR imaging.