farnoosh taghavi

Although a high prevalence of periodontitis has been reported in patients with rheumatoid arthritis (RA), the possible association between the severity of periodontitis and RA disease activity remains unclear.

This study was performed on 73 patients with RA selected according to the criteria of the American College of Rheumatology who were referred to a rheumatology clinic in Qazvin in 2021. The activity of the RA disease was evaluated by the Disease Activity Score 28 (DAS28), and the severity of periodontitis was evaluated by clinical attachment loss (CAL) and plaque index (PI). Age, sex, duration of disease, and type of treatment were also recorded. The Kolmogorov-Smirnov test was used to evaluate the normal distribution of quantitative variables, and the chi-square test was used to investigate the relationship between qualitative variables.

Patients with RA were predominantly women (86.3%) between the ages of 25 and 73. The average duration of the disease was 5.78 years with a range of 3 months to 30 years. The majority of RA patients had moderate disease activity (47.9%) and the lowest prevalence was for the low disease activity (8.2%). Most of the patients had mild periodontitis (65.8%). The highest mean of PI was observed in patients with severe disease activity and the patients at the remission stage had the least PI level, but the difference was not significant (P = 0.574). In dental examination, 24(32.9%) patients had moderate to severe periodontitis unrelated to the higher disease activity (P = 0.372).

No significant relation was observed between RA disease activity and periodontitis severity.

 The objective of the current research was to evaluate how stress is distributed in the peri-implant bone of a mandibular overdenture with implants placed asymmetrically to the midline.

 A 26-year-old male’s mandible, with missing teeth, was examined using computed tomography (CT) scanning. Two implants were inserted at right angles to the occlusal plane, in the positions of the right canine and left lateral incisor of the mandible, with an internal connection. Two types of attachments (bar and ball) were designed. To simulate the clinical condition, anterior (on central incisors) and bilateral posterior (on premolars and molars) loadings were applied. The stress distribution was assessed using finite element analysis (FEA).

 The lateral incisor level implant was found to have the highest maximum principal stress (about 33 MPa) in both models in the anterior loading condition. However, in both models, the canine-level implant revealed more stress values (about 22 MPa) in the posterior loading condition.

 In mandibular implant-supported overdentures, when implants were placed asymmetrically to the midline, one acted as a fulcrum and sustained more occlusal load. The bar attachment system did not reveal superior results in terms of stress distribution compared to the ball attachment.

Implant-supported overdentures are a treatment option for edentulous patients. One of the important factors in determining the prognosis of overdenture treatment is to control the distribution of stress in the implant-bone and attachment complex. This study assessed the effect of implant abutment height difference on stress distribution in mandibular overdentures.

In this study, three models of mandibular overdentures were designed independently using finite element analysis (FEA). The implants were placed at different height levels relative to the adjacent implant (1 mm, 2 mm and 3 mm). A 100 N load was applied to the overdenture, and the software was programmed for stress analysis in the models. The load was applied bilaterally, unilaterally, vertically, and obliquely. Finally, the von Misses stresses were produced numerically, color-coded, and compared among the models.

The models in which the implants had up to 2 mm height difference with each other showed better stress distribution than the model with 3 mm height difference between the implants. In all conditions, the implant neck showed the high-est concentration of stress among all areas of the implant. Lower stress levels were found in the cancellous bone than the cortical bone in different loading conditions.

Lower Von Mises stress values were found in the models with up to 2 mm difference in implant height, and higher stress values were noted in the cortical bone and the implant neck compared with trabecular bone.

There is a risk of nerve injury during the extraction of the impacted third molars, in cases with proximity of the inferior alveolar nerve and this tooth. The aim of this study was to evaluate the effect of different various factors on the degree of vulnerability using CBCT (Cone Beam Computed Tomography) imaging technique. CBCT images of 191 patients referred for the exact assessment of the relationship between the mandibular canal and impacted mandibular third molars were selected. The position of these anatomical structures was evaluated at their contact point. The possible effect of gender, impaction form of the third molars, anatomical relationship between the third molars and the mandibular canal and the age differences were studied. Data were analyzed using Chi-square and Student’s t-test. There was a close relationship between the mandibular canal and impacted third molars in 81.7% of the patients. The contacts were shown to be significantly higher in females than males (P=0.01) and in the cases with the lingually position of the third molar and the mandibular canal (P<0.001). However, the age and impaction form of the teeth did not have a significant influence (P>0.05). The risk of nerve damage or exposure is increased in females and lingual position of the mandibular canal to the third molar in cases with higher proximity between these 2 structures in panoramic radiographs using CBCT images. Therefore, the surgeon must pay enough attention in these cases of third molar extraction.