ABSTRACT
Statement of the Problem: Accurate measurement of the available bone height is an essential step in the pre-surgical phase of dental implantation. Panoramic radiography is a unique technique in the pre-surgical phase of dental implantations because of its low cost, relatively low-dose, and availability
Purpose: This article aimed to assess the reliability of dental panoramic radiographs in the accurate measurement of the vertical bone height with respect to the horizontal location of the alveolar crest
Materials and Method: 132 cone-beam computed tomography [CBCT] of the edentulous mandibular molar area and dental panoramic radiograph of 508 patients were selected. Exclusion criteria were bone abnormalities and detectable ideal information on each modality. The alveolar ridge morphology was categorized into 7 types according to the relative horizontal location of the alveolar crest to the mandibular canal based on CBCT findings. The available bone height [ABH] was defined as the distance between the upper border of the mandibular canal and alveolar crest. One oral radiologist and one oral surgeon measured the available bone height twice on each modality with a 7-dayinterval
Results: We found a significant correlation between dental panoramic radiographs and cone-beam computed tomography values [ICC=0.992, p< 0.001]. A positive correlation between the horizontal distance of the alveolar crest to the mandibular canal and measured differences between two radiographic modalities had been found [r=0.755, p< 0.001]. For each single unit of increase in the horizontal distance of the alveolar crest to the mandibular canal, dental panoramic radiographs showed 0.87 unit of overestimation [p< 0.001]
Conclusion: Dental panoramic radiographs can be employed safely in the pre-surgical phase of dental implantation in posterior alveolus of mandible, especially in routine and simple cases
ABSTRACT
Statement of the Problem: The most important risk factor for inferior alveolar nerve [IAN] damage is the proximity of the mandibular root apices to the alveolar canal. Failure to position the patient's head at standardized orientation during cone beam computed tomography [CBCT] scans might adversely affect the relative position of the alveolar canal and mandibular root apices with subsequent treatment failure
Purpose: The purpose of the present study was to investigate the influence of the orientations of the skull during the scanning procedure on the accuracy of CBCT images in determining the positional relationship of the mandibular tooth apices to the alveolar canal
Materials and Method: CBCT scans of 7 human dry skulls were obtained by using NewTom VGi CBCT in standard, tilt, flexion, extension and rotation positions of the head. The shortest radiographic distance between the mandibular tooth apices and the IAN canal of 20 points were measured on cross sectional images of CBCT in all position scans. A sample t-test was used to compare the measurements at different head position with the standard position values
Results: Significant differences were found in the measurements of normal and tilt orientations. However, there was no statistically significant difference between the measurements in standard position and other deviated positions. The mean errors in all head positions were less than 0.5mm
Conclusion: Alteration of patient head positioning during CBCT scanning does not affect the relative position of the IAN and the apices of posterior teeth
Subject(s)
Humans , Mandibular Nerve , Tooth Apex , Alveolar Process , Head Movements , Head-Down Tilt , Patient PositioningABSTRACT
Statement of the Problem: Finding a significant relationship between temporomandibular joint [TMJ] morphology and the incidence of temporomandibular dysfunction [TMD] may help early prediction and prevention of these problems
Purpose: The purpose of the present study was to determine the morphology of mandibular fossa and the articular eminence inclination in patients with TMD and in control group using cone beam computed tomography [CBCT]
Materials and Method: The CBCT data of bilateral TMJs of 40 patients with TMD and 23 symptom-free cases were evaluated. The articular eminence inclination, as well as the glenoid fossa depth and width of the mandibular fossa were measured. The paired t-test was used to compare these values between two groups
Results: The articular eminence inclination and glenoid fossa width and depth were significantly higher in patients with TMD than in the control group [p < 0.05]
Conclusion: The articular eminence inclination was steeper in patients with TMD than in the control group. Glenoid fossa width and depth were higher in patients with TMD than that in the control group. This information may shed light on the relationship between TMJ morphology and the incidence of TMD
ABSTRACT
Statement of the Problem: The adhesion of resin-modified glass-ionomer [RMGI] to composite resin has a very important role in the durability of sandwich restorations. Hydroxyapatite is an excellent candidate as a filler material for improving the mechanical properties of glass ionomer cement
Purpose: The aim of this study was to assess the effect of adding micro- and nano-hydroxyapatite [HA] powder to RMGI on the shear bond strength [SBS] of nanofilled and silorane-based composite resins bonded to RMGI containing micro- and nano-HA
Materials and Method: Sixty cylindrical acrylic blocks containing a hole of 5.5×2.5 mm [diameter × height] were prepared and randomly divided into 6 groups as Group 1 with RMGI [Fuji II LC] plus Adper Single Bond/Z350 composite resin [5.5×3.5 mm diameter × height]; Group 2 with RMGI containing 25 wt% of micro-HA plus Adper Single Bond/Z350 composite resin; Group3 with RMGI containing 25 wt% of nano-HA plus Adper Single Bond/Z350 composite resin; Group 4 with RMGI plus P90 System Adhesive/P90 Filtek composite resin [5.5×3.5 mm diameter × height]; Group 5 with RMGI containing 25 wt% of micro-HA plus P90 System Adhesive/P90Filtek composite resin; and Group 6 with RMGI containing 25 wt% of nano-HA plus P90 System Adhesive/P90 Filtek composite resin. The specimens were stored in water [37 degree C, 1 week] and subjected to 1000 thermal cycles [5 degree C/55 degree C]. SBS test was performed by using a universal testing machine at a crosshead speed of 1 mm/min. Data were analyzed by two-way ANOVA and Tukey test [p< 0.05]
Results: There were significant differences between groups 1 and 4 [RMGI groups, p= 0.025], and groups 3 and 6 [RMGI+ nano-HA groups, p= 0.012]. However, among Z350 and P90 specimens, no statistically significant difference was detected in the SBS values [p= 0.19, p= 0.083, respectively]
Conclusion: RMGI containing HA can improve the bond strength to methacrylate-based in comparison to silorane-based composite resins. Meanwhile, RMGI without HA has the best bond strength to silorane-based composite resins
ABSTRACT
Statement of the Problem: According to previous studies, the components of green tea extracts can inhibit the growth of a wide range of gram-pos-itive and -negative bacterial species and might be useful in controlling oral infections
Purpose: The aim of this study was to determine the effect of green tea chewing gum on the rate of plaque and gingival inflammation in subjects with gingivitis
Materials and Method: In this double-blind randomize controlled clinical trial, 45 patients with generalized marginal gingivitis were selected and divided into two groups of green tea [23] and placebo [22] chewing gum. The patients chewed two gums for 15 minutes daily for three weeks. Sulcus bleeding index [SBI] and approximal plaque index [API] were studied at the baseline, 7 and 21 days later. Saliva sampling was conducted before and after 21 days for evaluation of IL-1beta. The results were analyzed and compared by using repeated measures ANOVA, paired t test, and independent two-sample t test [alpha=0.05]
Results: The results showed that chewing gum significantly affected the SBI and API [p< 0.001]. Paired t test showed that the two groups were significantly different regarding the mean changes of SBI and API at different periods of 1-7, 1-21, and 7-21 [p< 0.001]. Concerning IL-1beta, the repeated measures ANOVA revealed that the effect of chewing gum was significant [p<0.001]. Moreover, paired t-test represented no significant difference between the mean changes of IL-1beta within 1-21 day [p= 0.086]
Conclusion: The green tea chewing gum improved the SBI and API and effectively reduced the level of IL-1beta