Journal of Dentistry, Shiraz University of Medical Sciences
Volume:22 Issue: 4, Dec 2021

 Composite restoration failures may occur because of different factors. In these situations, the repair of a composite restoration has many advantages over replacement such as saving time, lower cost, and lower risk of excessive removal of sound tooth structure and subsequent pulp exposure.

The purpose of this in vitro study was to evaluate the effects of two surface treatments on shear bond strength (SBS) of new composite to old composite.

In this in vitro study ,60 composite discs were fabricated using a plexiglass mold measuring 4 mm in thickness and 7 mm in diameter, and were randomly divided into three groups (n=20). In group 1, the bonding procedure was done with no modification. After roughening of one surface in all remaining samples, chloroform (CHCl3) was applied on the surface of samples in group 2 and phosphoric acid 35% was applied on the surface of the samples in group 3. PermaSeal was then applied in all samples and new composites were bonded to the surface. The samples were stored in distilled water for one week and were then subjected to 500 thermal cycles and shear bond strength between two layers of composite and mode of failures were evaluated.

The lowest and the highest SBS values of repair composite to old composite were noted in groups 3 and 1, respectively and this difference was statistically significant (p < 0.05).The difference between groups 1 and 2 was not significantly different (p = 0.197). The mode of failure was mixed in all samples of groups 2 and 3 and cohesive in group 1.

After grinding, the surface treatment with phosphoric acid did not increase the SBS of new composite to old composite, while chloroform increased the SBS almost to the level of the baseline in control group.

 Streptococcus mutans, Streptococcus sanguinis, and Streptococcus salivarius are most common etiologic bacteria for dental caries. Different sizes of gold nanoparticles may have different antibacterial effects on these species.

This study aimed to compare the antibacterial effect of chlorhexidine and three sizes of gold nano particles (25, 60, 90nm) against clinical and standard strains of Streptococcus mutans, Streptococcus sanguinis, and Streptococcus salivarius.

In this cross-sectional study, the specimens were collected from 75 children aged 3-5 years old. Antibacterial effect of chlorhexidine and three sizes of gold nano particles (25, 60, 90nm) were investigated by evaluating the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against three bacterial strains.

The MIC and MBC of gold nanoparticles with different sizes against Streptococcus mutans, Streptococcus sanguinis, and Streptococcus salivarius were statistically different. The MIC and MBC of smaller gold nano particles (25nm) were significantly lower (p <0.001) than larger ones. Patient-derived bacteria had significantly higher values of MIC and MBC in comparison to standard species (p <0.001).

The results of this study confirmed the significant size-dependency of gold nano particles for antibacterial activity. As the size of gold nano particles decrease, the antibacterial properties enhance.

 The smear layer may harbor microorganisms and necrotic pulp tissue, jeopardizing irrigant penetration. Recently, Dual Rinse®, a weak chelating agent, has been introduced to the market. However, its chelating capacity in the final irrigation protocol with different activation systems has not yet been deeply analyzed.

The aim of this ex vivo study was to evaluate the effectiveness of passive ultrasonic irrigation (PUI) and XP-endo Finisher (XP) on smear layer removal in combination with two chelating agents, ethylenediaminetetraacetic acid (EDTA), and etidronic acid (HEDP).

Fifty-two single-rooted human teeth were standardized to 16 mm in length. Root canal instrumentation was performed by the ProTaper Gold system up to the F4 file. The apical end of the samples was sealed with wax to simulate a closed system. Teeth from group 1 (n=24) were irrigated with 3% sodium hypochlorite (NaOCl) and 17% EDTA, while teeth from group 2 (n=24) were irrigated with 3% NaOCl mixed 9% HEDP. Both groups were divided into two subgroups (n=12) depending on the activation system used: XP (group XP-EDTA and XP-HEDP) or PUI (group PUI-EDTA and PUI-HEDP). The specimens were evaluated by scanning electron microscopy at 3, 5 and 8 mm from the apex. Statistical analysis was performed using ANOVA and Bonferroni tests considering p >0.05 as significant.

PUI-EDTA was the most effective at removing the smear layer, with a statistically significant difference from XP-EDTA (p <0.042) and group XP-HEDP (p <0.003). There were no statistically significant differences among the other groups.

Under the conditions of this ex vivo study, no activation system was able to completely remove the smear layer from the root canal walls. However, the combination of NaOCl with ultrasonically activated EDTA obtained better results than the other treatments.

Monolithic zirconia restoration has been introduced to overcome the porcelain chipping. Different factors can affect the color of monolithic zirconia, so achieving the desired color in the restorations is considered as a challenge.

The purpose of this in vitro study was to determine the effect of different foundation materials on the color of monolithic zirconia at different thicknesses.

In this experimental study, thirty ceramic disks in three thicknesses (i.e. 0.6mm, 1.1mm and 1.5mm) were fabricated from high translucency shade A2 monolithic zirconia block. Disk shaped foundation materials were fabricated from nickel chromium alloy (Ni-Cr), non-precious gold alloy (NPG), zirconia, and shade A2 composite resin. The color was measured by a spectrophotometer. The color differences (∆E) in the control and the test groups were calculated. The data were analyzed using two way ANOVA and compared with the posthoc Tukey test (a=0.05).

ceramic thickness and foundation materials had a significant effect on the mean values of ∆E of monolithic zirconia ceramics (p= 0.001). The highest amount of ∆E value was observed in NPG, while Ni-Cr resulted in the lowest ∆E. Unacceptable results (∆E>2.25) were observed for monolithic zirconia ceramics on NPG foundation material with a thicknesses of 0.6 and 1.1mm. The mean L* values of all foundation materials were higher than those of the control group except for Ni-Cr. The highest a* was seen in NPG and the mean b* values of all tested foundation materials were higher than those of the control group except for Ni-Cr.

Increasing the thickness of monolithic zirconia decreased the color mismatch. High translucent monolithic zirconia could mask the color of Ni-Cr and zirconia in all three thicknesses (∆E˂2.25), while it could not mask the color of NPG under thickness of 1.5mm.

The success of dental restorations depends mainly on its ability to bond to dental structures and resist the multitude of forces acting on it within the oral cavity.

Therefore, the aim of this study was to evaluate the shear bond strength (SBS) of three different glass ionomer based restorative materials.

In this in vitro analytical study, 30 intact primary molars were sectioned buccolingually to obtain 60 sections. These sections were embedded in auto polymerizing acrylic resin and polished to obtain a flat dentin surface. Restoration cylinders were built on the dentin surface with the help of a Teflon template called bonding jig. Each group (n= 20) was restored as group A with conventional glass ionomer cement (GIC) (GC Fuji Gold Label Type 9), group B with Bioactive restorative material (ACTIVATM KIDS BioACTIVE Restorative material), and group C with Zirconia reinforced glass ionomer cement (Zirconomer). Following restoration, SBS testing was performed using Universal Testing Machine. The data obtained were statistically analyzed using One way ANOVA test and post hoc Tukey test (p= 0.05).

The SBS values were significantly greater in the ACTIVA KIDS group as compared to the other two groups (p< 0.05). There was no significant difference in the SBS values between group B and group C (p> 0.05).

The SBS of the ACTIVA KIDS to primary teeth dentin was the highest as compared to Zirconomer and conventional GIC. Therefore ACTIVA KIDS may protect primary teeth against recurrent caries and failure of the restoration.

Considering the relatively high prevalence of oral mucosal ulcers, their fast healing is of significance.

This study aimed to histopathologically compare the effects of 810 nm and 940 nm diode laser on the healing of iatrogenic oral ulcers in rabbits.

In this single-blind experimental study, mucosal ulcers measuring 3mm in diameter and 1mm in depth were bilaterally created in the buccal mucosa of 18 rabbits using a biopsy punch. The defects were irradiated with 810 nm diode laser on the right side and 940 nm diode laser on the left side. Biopsy samples of the same depth were obtained from the ulcers on days 3 and 7 followed by histopathological analysis. The intensity of inflammation was determined on hematoxylin-eosin-stained sections using a four-point scale. Data were analyzed employing the Wilcoxon signed rank test.

Thedegree of inflammation was not significantly different between the 810nm and 940nm diode laser groups on day 3; but on day 7, animals receiving 810 nm experienced a significantly lower degree of inflammation compared to those treated with 940 nm laser (p= 0.028).

When comparing 810- and 940-nm diode lasers, 810 nm irradiation significantly decreased the severity of inflammation in oral wounds created on the buccal mucosa of rabbits in a time-dependent manner.

Odontogenic infections such as periapical lesions (PLs) can cause changes in the adjacent tissues. Infection of the maxillary posterior teeth can be easily transmitted to the maxillary sinus and cause changes in the maxillary sinus mucosa. Cone-beam computed tomography (CBCT) has high accuracy and sensitivity for detection of odontogenic lesions and is efficient for maxillary sinus assessment.

This study aimed to assess the maxillary sinuses for abnormalities such as mucosal thickening, polyps, and periostitis, and evaluate the periapical status of maxillary posterior teeth considering the presence of PLs, their size and distance from the sinus floor by evaluating CBCT images.

This retrospective, cross-sectional study evaluated the CBCT scans of 143 patients, depicting the posterior maxilla with at least one premolar or molar tooth present in this region. Sinus abnormalities (mucosal thickening, sinus polyps, and periostitis) and presence/ absence of PLs, its size, and its distance from the sinus floor were all assessed on CBCT scans. Data were analyzed using the Chi-square test in SPSS version 21 (a= 0.05).

PLs were observed in 31.2% of the cases. In presence of PLs, mucosal thickening was noted in 56.8%, sinus polyps in 29.6% and periostitis in 1.3% of the maxillary sinuses. All teeth with a CBCT periapical index (CBCTPAI) score of 5 were associated with sinus abnormalities; there was neither correlation between the sizes of lesions, nor their distance from the sinus floor with sinus abnormalities (p > 0.05).

PLs in the posterior maxilla have a direct correlation with the maxillary sinus abnormalities. However, the size or distance of PLs from the sinus floor had no significant effect on the frequency of sinus abnormalities.

Poly-etheretherketone is a novel material used in the construction of the removable partial dentures frameworks instead of the metal frameworks. This material can be fabricated by various techniques. Most common methods are the injection molding or Computer Aided Design/Computer Aiding Manufacturing (CAD/CAM) milling techniques. The fabrication technique may affect the adaptation of the frameworks by influencing the retention.

To assess the effect of the processing techniques of high performance Poly-etheretherketone either by injection molding (pressing) or  CAD/CAM  milling techniques on removable partial denture frameworks retention for rehabilitation of upper class I Kennedy classification.

This in vitro studywas performed on one epoxy resin model representing the partially edentulous maxillary arch with natural teeth extending from first premolar to first premolar. First premolars and canines were reduced to receive porcelain fused to metal crowns with 0.50mm mesio-buccal retentive undercuts, distal guiding planes and mesial occlusal rest seat on first premolars and cingulum rest seat on canines. Considering the construction technique of frameworks, twenty samples were divided into two groups. In the group I, ten frameworks were fabricated by injection molding, and in the group II, ten frameworks were fabricated by CAD/CAM. The removal and insertion was carried out at 120, 720 and 1440 cycles for both groups, respectively. The retention values were measured by using Universal Testing Machine before cycling and after each interval.

Independent t-test showed significant difference on retention at different simulation cycles between groups. Group II exhibited significantly less retention than group I (p< 0.001), while comparing the retention at different cycles within each group by paired sample t-test exhibited significant decrease of retention till the end of the cycling (p< 0.001).

From the retention point of view, high performance poly-etheretherketone frameworks fabricated by injection molding technique provided a promising method over CAD/CAM technique milling method.

 A mineral trioxide aggregate (MTA) apical plug is commonly applied prior to endodontic treatment of open-apex teeth. However, difficult application and condensation of MTA in the apical region is a drawback of this technique.

This study aimed to compare the microleakage of MTA apical plug applied by the manual technique and indirect use of ultrasonic with different powers.

In this in vitro, experimental study, divergent open apices were created in 48 single-rooted, single-canal teeth using ProFile. The teeth were randomly divided into four experimental groups (n=10). All groups received 5-mm thick MTA apical plug at the apical region using one of the following methods. In group 1, MTA was manually condensed while in groups 2-4, indirect ultrasonic energy with minimum, medium, and maximum power levels was used for MTA plug condensation. After setting of MTA, the apical microleakage of the MTA plug was quantified using the fluid filtration method. Data were analyzed using the Mann-Whitney and Kruskal-Wallis tests (p < 0.05).

Significant differences were noted in microleakage of MTA plug between the manual group and ultrasonic groups with medium (p = 0.043) and maximum (p = 0.029) power levels. No significant difference was noted in microleakage of other groups (p > 0.05).

Considering the current results, it seems that application of MTA with indirect ultrasonic energy at medium or high power level would decrease the microleakage of MTA plug in open-apex root canals.

Peri-implantitis is a site-specific infectious disease that causes an inflammatory process in soft tissues, and bone loss around an osseointegrated implant in function. Several techniques with non‐surgical or surgical debridement and decontamination followed by ongoing supportive therapy or regeneration of the peri‐implant bone defects have been proposed in the literature. However, the literature is still unclear on an effective protocol for implant surface decontamination or the appropriate choice of regenerative materials. This case series describes a surgical technique to treat peri-implantitis osseous defects using a mixture of deproteinized bovine bone mineral with 10% porcine collagen (DBBM-C) in a block form, soaked in an appropriate antibiotic. The use of this combination provides advantages such as good graft adaptability along with localized antibiotic release without the use of systemic antibiotics. Thus, this technique might be an effective method to treat amenable peri-implantitis defects. Additionally, the proposed algorithm also allows for customized culture based antibiotic loading. To the best of the authors’ knowledge, this is the first case series documenting this technique for peri-implantitis defects. Long-term studies with controlled samples would be necessary for further evaluation.

Odontomas are benign tumors of jaws with mixed tissue, which are the result of proliferation of odontogenic epithelium and mesenchymal cells. They occur almost centrally and seldom peripherally. There is no report of such a lesion externally while attaching a tooth crown. In this case, we present a lesion on the buccal surface of the right maxillary central incisor crown, which is misconstrued with a dental overgrowth. Such cases may confuse diagnosis during clinical examination. Radiographically, such odontomas may be mistaken for various other lesions. Ultimate diagnosis should be relied upon microscopic evaluation and histopathological results.

The extraction of retained and completely impacted third molars is one of the most common surgical procedures performed by dental practitioners with low rates of complications. The accidental displacement during the surgeries of the maxillary third molar into adjacent anatomical spaces is one of the most critical problems that can arise. The most common sites of migration during surgical interventions are the infratemporal fossa, the pterygomandibular space, the maxillary sinus, the buccal space, and the lateral pharyngeal space. In this paper, two cases in which a maxillary third molar accidentally was displaced into the buccal space are presented, the retrieval of the tooth via intra-oral approach is explained, and the anatomical spaces implications are discussed.