Journal of Islamic Dental Association of IRAN
Volume:34 Issue: 1, Winter-Spring 2022

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.

Dysplastic lesions are characterized by replacement of parts or all of the epithelium thickness with cells with variable degrees of atypia and abnormal maturation. The aim of this study was to clinicopathologically evaluate oral dysplastic lesions recorded in the Oral Pathology Department of Isfahan Dental School during a 30-year period.

This cross-sectional study was performed on 130 records of patients diagnosed with dysplastic lesions at the Oral Pathology Department of Isfahan Dental School from 1989 to 2018. The patients’ data were entered into SPSS version 23 and analyzed by the Kruskal-Wallis test, Mann-Whitney test, and Spearman’s correlation test. P values < 0.05 were considered statistically significant.

From 11,964 recorded cases during the abovementioned 30-year period, 130 cases were oral dysplastic lesions. Most of the patients were in their fifth and sixth decades of life (24.6% and 23.3%, respectively). There was no significant correlation between the severity of dysplasia and gender (p=0.45). Sixty-two cases (47.7%) had white and red lesions in clinical examination. Buccal mucosa was the most common site of involvement. The most commonly recorded clinical differential diagnoses included lichen planus, leukoplakia, and squamous cell carcinoma, in decreasing order of frequency.

Considering the importance of early diagnosis and treatment of oral dys-plastic lesions, having comprehensive and up-to-date information about their clinico-pathological characteristics is necessary. Since most of such lesions have mild dys-plastic changes, their aggravation and malignant transformation can be prevented by early diagnosis.

Benign migratory glossitis, or geographic tongue, is usually an asymptomatic inflammatory disorder of unknown etiology that affects the epithelium of the tongue. Among the etiologic factors proposed, emotional causes were suspected by several investigators. The objective of this study was to evaluate the anxiety and cortisol level in patients with geographic tongue compared with healthy controls.

In this case-control study, 21 patients with geographic tongue referred to several educational and medical centers in Hamedan city were se-lected. The patients had no systemic disease or history of cigarette smoking. A control group of 21 healthy individuals without geographic tongue, systemic diseases and cigarette smoking was also selected. The participants were asked to complete the Beck Anxiety Inventory. Also, unstimulated saliva samples were collected to measure the salivary cortisol level in both groups. The two groups were compared after adjusting for age and gender. The Mann-Whitney test was used to com-pare the salivary level of cortisol in the two groups with and without geographic tongue.

The anxiety score of the geographic tongue group was higher but not significantly (P=0.745). The concentration of salivary cortisol was significantly higher in the control group (P=0.01). No strong correlation was found between the salivary cortisol level and the Beck Anxiety Inventory score.

It seems that among various factors associated with geographic tongue, psychological conditions are less related.

Medical grade calcium sulfate hemihydrate (MGCSH) is used as a bone graft material for socket preservation. This study aimed to evaluate the changes in bone width and height after tooth extraction and socket preservation with MGCSH using cone-beam computed tomography (CBCT).

This study evaluated 17 systemically healthy patients over a 1-year period. The patients were selected among those presenting to an outpatient department. CBCT was taken with a radiographic stent and extraction was performed; socket dimensions were measured. Socket preservation was performed using MGCSH. After 3 months, another CBCT was taken, and socket dimensions were measured. The change in socket dimensions was quantified by com-paring the preoperative and postoperative radiographs. Comparisons were made by paired t test.

At 3 mm from the initial ridge crest, the mean bone width was 6.24 ± 1.73 be-fore and 4.74 ± 1.91 mm after 3 months; this difference was statistically significant (P<0.001). At 6 mm, the mean bone width was 7.05 ± 1.50 before and 5.49 ± 1.82 mm after 3 months; this difference was also statistically significant (P< 0.001). At 9 mm, the mean bone width was 7.46 ± 2.16 mm before and 5.71 ± 1.75 mm after 3 months; this difference was statistically significant (P<0.001). The initial mean height was 12.16 ± 2.21mm, which changed to 12.99 ± 2.69 mm at 3 months, with no signifi-cant difference (P=0.22).

Socket preservation with MGCSH caused a significant change in ridge width, but not in ridge height.

Minimizing the polymerization shrinkage of composite resins is a critical goals in composite restorations. Many factors affect polymerization shrinkage. This study aimed to evaluate the effect of composite resin shade on polymerization shrinkage.

In this in vitro study, 14 composite discs measuring 1.5×8 mm were fabricated. The samples were prepared using the A2 and WB shades of G-aenial composite resin. Composite resin discs were placed in a brass ring bonded to a glass slide. Another glass slide was placed over it. The samples were light-cured at 750 mW/cm2 light intensity for 20 seconds. Polymerization shrinkage (shrinkage re-action) and its strain rate were measured for up to 600 seconds after the onset of irra-diation by the bonded disc technique and a linear variable differential transformer (LDTV) machine. Data were analyzed by independent-sample t-test (P≤0.05).

The polymerization shrinkage strain at 20 and 600 seconds was not significantly different between the WB and A2 shades of G-aenial composite resin. The differences in polymerization shrinkage in each group at 20 and 600 seconds were significant (P<0.000). The difference in the shrinkage rate between the two groups up to 20 seconds was not significant (P=0.505).

The polymerization shrinkage of G-aenial composite resin was not affected by shade. However, in both shades, polymerization shrinkage showed a sig-nificant difference immediately after irradiation and 600 seconds after that.

Odontomas are the most common type of odontogenic tumors of the oral cavity and are described as one of the contributing factors to tooth impaction. The impaction of the maxillary incisors causes several esthetic and functional problems. A multidisciplinary approach is required for proper planning, surgical pro-cedure, and orthodontic traction of the impacted tooth.

The aim of this case report is to present a clinical case of a 10-year-old female patient with the chief compliant of absence of the upper right per-manent central incisor. Radiographic examination revealed that over-retention of the right central incisor was associated with a mixed lesion showing tooth-like structures. The lesion, which was characterized as compound odontoma, was surgically removed. Because of the deep position of the impacted tooth, surgical exposure and orthodontic traction were planned after 10 months of watchful waiting.

Combined surgical and orthodontic treatments are recommended for impacted maxillary central incisors associated with odontoma.