Regeneration, Reconstruction & Restoration (Triple R)

Background and objectives: Establishing a strong and durable bond between cements and root canal dentin has been widely studied. Since the effectiveness of proanthocyanidin (PA) as a collagen cross-linker has been proven, the strength and durability of the bond between fiber posts and root canal dentin are expected to increase following the application of PA. Therefore, the present study aimed to assess the effect of PA pre-treatment on the bonding durability of fiber posts with three resin cements.

Materials and methods: Ninety human single-rooted teeth with similar anatomical root shape and length were collected. After decoronation and root canal therapy, the teeth were divided into nine groups: etch and rinse (ER), self-etch (SE), self-adhesive (SA), PA pre-treatment and etch and rinse (PAER), PA pre-treatment and self-etch (PASE), PA pre-treatment and self-adhesive (PASA), chlorhexidine (CHX) pre-treatment and etch and rinse (CHXER), CHX pre-treatment and self-etch (CHXSE), and  [ CHX pre-treatment and self-adhesive (CHXSA). After microslicing the roots, push-out tests were performed immediately for half the specimens and after three months of water storage and thermocycling for the other half. Data were analyzed using two-way ANOVA and Tukey’s test with α=0.05.

Results: Resin cement type (P=0.001), dentin pre-treatment method (P=0.001), water storage and thermocycling (P=0.001), and the root region (P=0.001) had significant effects on bond strength.

Conclusion: SA resin cement had the lowest immediate and long-term bond strength in comparison with the other two cements. For ER and SE resin cements, no pre-treatment led to higher immediate and long-term bond strength. For SE and SA resin cements, PA pre-treatment inhibited the loss of bond strength in the long-term. The bond strength in the coronal region was higher than that in other regions.

Background and objectives:  This study aimed to investigate the in vitro effects of two Listerine mouthwashes—one alcohol-free and the other containing alcohol—on the shear bond strength of orthodontic brackets.

Materials and methods: This experimental study was accomplished on 45 healthy human premolars that were extracted for orthodontic treatment. The teeth after mounting in acrylic blocks were bonded with metal orthodontic brackets (MBT/0.22) by composite and randomly divided into three groups: (1) alcohol-containing Listerine mouthwash (ACLM), (2) alcohol-free Listerine mouthwash (AFLM), (3) artificial saliva (control). 15 samples were placed in each group. After keeping teeth in the solutions, the shear bond strength of orthodontic brackets was measured by the universal testing machine at a speed of 1 mm/min, and the information was compared using one-way ANOVA analysis.

Results: In general, the average shear bond strength of 45 premolars was evaluated as 20.92±6.8 MPa. Shear bond strength was reported as 18.32±7.33 MPa in the first group (Listerine containing alcohol), 22.33±7.27 MPa in the second group (Listerine without alcohol), and 22.22±5.27 MPa in the third group (control group). The highest and lowest mean shear bond strength of the bracket to the tooth surface were shown in the alcohol-free Listerine and the alcohol-containing Listerine groups, respectively. The results of one-way ANOVA showed no statistically significant difference in terms of shear bond strength among the three groups (P-value˃0.05).

Conclusion: Since both alcohol-containing and alcohol-free Listerine mouthwashes are effective in reducing viral and oral microbial loads, the lack of significant impact on bracket bond strength supports the recommendation of these mouthwashes in orthodontic practice.

Background and objectives: This study assessed the effect of thickness of high-translucent (HT) and super-translucent (ST) monolithic zirconia on its color, translucency, and marginal and internal adaptation.

Materials and methods: Monolithic zirconia restorations were fabricated from HT and ST zirconia blanks (n=30) with 0.5-, 1- and 1.5-mm thicknesses (n=10). The color and translucency parameter (TP) was measured by a spectrophotometer, and marginal gap (MG), internal gap (IG), and occlusal gap (OG) were measured by the replica technique.

Results: Zirconia type had no significant effect on TP (P=0.362) but the effect of thickness was significant (P<0.001); 1.5-mm thickness yielded the lowest and 0.5-mm thickness yielded the highest TP. Zirconia type (P<0.001) and thickness (P=0.001) had significant effects on color difference (ΔE); ST yielded significantly higher ΔE, and 0.5-mm thickness resulted in significantly lower ΔE than 1-mm (P=0.047) and 1.5-mm (P<0.001). The MG of both HT and ST increased with thickness (P<0.05). The IG of 0.5 mm-thick restorations was significantly higher than 1 mm (P=0.005) and 1.5 mm (P=0.003). In ST restorations, the difference in IG was not significant among different thicknesses (P>0.05). OG was the highest in 0.5 mm thickness. In ST restorations, minimum OG was found in 1 mm thickness. Zirconia type had no significant effect on adaptation (P>0.05).

Conclusion:  Zirconia type had no significant effect on TP or adaptation. Increasing the thickness decreased TP. ΔE was lower in lower thicknesses, and ST zirconia yielded higher ΔE. Thickness had a direct correlation with MG and an inverse correlation with IG and OG.

Background and objectives: The most important anatomical areas to take into account during implant insertion are the submandibular gland cavity, the posterior part of the mandible, and the inferior alveolar nerve. Therefore, this study aims to assess the location of the submandibular gland fossa and its variations using CBCT.

Materials and methods: In this cross-sectional investigation, CBCT images of the mandible of patients who visited a private radiology center in Babol (Mazandaran, Iran) between 2019 and 2021 were included. The submandibular salivary gland fossa was evaluated based on age, sex, side of the mandible, fossa depth and angle, as well as connection with the mental foramen and mandibular canal. Data were analyzed using SPSS V.24.

Results: The study population comprised 59 men (47.2%) and 66 (52.8%) women, ranging from 16 to 70 years old. The mean depth of the fossa on the right side (1.79 ± 0.48 mm) was statistically greater than the left side (1.66 ± 0.46 mm). Regarding the angle of the fossa and the distance to the mental foramen, there was no discernible difference between the left and right sides. Men had considerably deeper average fossa depths on both sides (P<0.05). Moreover, the fossa depth on the right side was significantly lower in patients less than 36 years old (P=0.005).

Conclusion: According to the current findings, the average depth of the fossa is greater on the right side than on the left side. The deepest part of the fossa is located next to the mandibular canal. Therefore, it is crucial to have a thorough understanding of the characteristics of the submandibular gland fossa to avoid perforating the lingual alveolar plate during implant insertion.

Keywords: Cone Beam Computed Tomography, CBCT, Dental implant, Submandibular gland fossa.

Background and objectives: Due to the lack of definitive conclusions about the effects of passive smoking on periodontal health especially in adults and the lack of information on the relationship between salivary calcium levels and periodontitis, this study aimed to compare salivary calcium levels and periodontal status of passive smoking and non-smoking adults.

Materials and methods: This cross-sectional study was conducted on 60 adult females in two groups of passive smokers and non-smokers (n=30), who were selected using consecutive sampling. The salivary calcium levels were measured using an enzymatic colorimetric method with a kit, and their periodontal health was evaluated by measuring clinical attachment loss (CAL), bleeding index (BI), and probing depth (PPD). The values were then compared between the two groups. Data were analyzed using t-tests, Mann-Whitney tests, Pearson and Spearman’s correlation coefficients (α=0.05).

Results: The mean CAL was significantly higher in passive smokers than in non-smokers (P=0.013). The mean values of BI (P=0.446), PPD (P=0.066), and salivary calcium levels (P=0.248) were not significantly different between the two groups, although slightly higher values were recorded in the passive group. In passive smokers, the mean PPD had a significant correlation with the salivary calcium levels (P=0.037). In non-smokers, CAL and salivary calcium levels were significantly correlated (P=0.010).

Conclusion:  Passive smokers had significantly greater CAL than non-smokers. Additionally, higher salivary calcium levels were significantly correlated with higher mean PPD in passive smokers and CAL in non-smokers, indicating a possible association between elevated salivary calcium levels and periodontal problems, regardless of smoking status.

Background and objectives:  The second common source of orofacial pain is temporomandibular disorder (TMD). Occlusal splints are prevalently applied to manage symptomatic TMD.  This study aimed to discuss the types, characteristics, fabrication, and application of occlusal splints.

Materials and methods: A structured search was carried out, including PubMed and Scopus databases with additional integration from external sources to March 2020. To meet the inclusion criteria, studies published in English involving randomized clinical trials, review articles, and experimental studies, starting from the 215 identified records, 75 items were finally included for the review.

Results: The critical step in treatment of patient with pain, malfunction, and discomfort is to determine the primary etiology. The two most commonly used splints are stabilization and anterior positioning appliances. Other types include anterior or posterior bite plane, pivoting appliance, and soft or resilient appliance.

Conclusion:  There are various splints in the literature; a dentist must select the appropriate one with predictive success based on the specific diagnosed TMD type.

Background and objectives: In this study, we aimed to report histopathological evaluation of the underlying tissues in a case of premature Titanium mesh exposure and assess the rate of Titanium mesh (Ti-mesh) exposure in the literature and its effect on treatment outcomes when used as a barrier membrane in jaw-bone reconstruction.

Materials and methods: We reviewed articles that used Ti-mesh with/without grafting materials to reconstruct atrophic ridges both vertically and/or horizontally. Considering our inclusion criteria, 51 studies were included. All relevant RCTs, retrospective studies (cohorts and case-controls) and case-series were included but case-reports and review articles were excluded. Data regarding premature exposure rate, removal rate, associated bone loss, and implant survival rate were extracted. Later, a report of an early Ti-mesh exposure in anterior maxillary horizontal augmentation with autogenous bone graft and deproteinized bovine bone mineral in a 50-year-old female is presented with a histological study of the underlying soft tissue at the time of mesh removal.

Results: A total of 51 studies were included in the review. Among the 41 studies reporting exposure, 18 reported removal of membranes, of which 3 caused significant bone loss. In the obtained biopsy from the reported case, a connective tissue infiltrated with sporadic inflammatory cells covered with keratinized stratified squamous epithelium was observed.

Conclusion: Our results indicate the loss of outcomes (both bone loss and implant failure) may not be associated with Ti-mesh exposure, which could, along with the rate of exposure, help the clinician assess the relative risk of its application.

Keywords: Alveolar ridge augmentation, Guided bone regeneration, Bone graft, Titanium mesh, Exposure.

Background and objectives: Trigeminal Neuralgia (TN) is a disabling neuropathic pain that can severely compromise the quality of life the patient. The current standard treatments for TN lack enough safety and efficacy; therefore, utilizing new remedies is mandatory. Photobiomodulation (PBM) is a novel treatment suggested for neuropathic pain, but we need more studies on using low-level laser to manage TN.

Materials and methods: 7 cases of primary confirmed TN were enrolled in this study. Diode laser (InGaAs) was utilized with 980 nm wavelength to irradiate the involved painful areas and trigger zones. Painful areas were irradiated intra and extraoral with the duration of 20 seconds and in osculation condition in continual wave (CW). The energy density of intra and extraoral irradiation was 4 j/cm² and 6 j/cm² respectively. Duration of treatment was about 3 weeks. VAS (Visual analogue scale) score was used as an outcome measure before and after treatment. Prior to enrollment, the VAS of self-reported pain of subjects was 10.

Results: VAS scores gradually decreased from the 4th session in all patients, as far as following 15th session. VAS scores in all patients were 1-2 degree at the end of third week of study. Along with PBM therapy, the dose of carbamazepine for pain management was reduced until the pain intensity was so low that it was not needed.

Conclusion: It seems that the PBM could be employed as adjuvant therapy for TN, but further study with precise laser dosing and more outcome measures are needed to apply this technology confidently.

One of the most challenging issues in the field of dentistry is to decide whether to preserve or extract a compromised tooth with subgingival caries/crown fractures. Several patient-related factors (i.e. biological, behavioral, or financial factors), tooth-related factors (i.e. periodontal, endodontic, or restorative factors), and the role of the tooth in the overall treatment plan should be considered to make the most accurate decision. This article has focused on the decision-making process related to the management of compromised teeth with subgingival caries/crown fractures. Based on the current scientific evidence and clinical experience of the authors, an algorithm has been suggested to simplify this process of decision. In the first step, compromised teeth were classified as single-root or multi-root groups. “Crown-to-root ratio” (C/R ratio), and “apical extension of caries to the crestal bone” were considered the main clinical parameters in the decision-making process for single-root and multi-root teeth, respectively. We do not recommend restoring the compromised teeth if the C/R ratio is more than 1 (for single-root teeth) or if the extension of caries has reached the alveolar bone crest (for multi-root teeth). For maintainable single-root teeth, there are three treatment options to provide space for the re-establishment of supracrestal soft tissue attachment (previously named as biologic width) between the future restorative margin and underlying crestal bone. These approaches include: surgical crown lengthening (SCL), orthodontic forced eruption (OFE), and deep marginal elevation (DME). For multi-root teeth, SCL and DME are usually the procedures of choice. Multi-root teeth are not amenable to OFE due to the heavy orthodontic forces needed for extrusion. We also discussed the indications and limitations related to each treatment option. Further studies should be conducted to evaluate the external validity of this decision tree.

Keywords: Decision trees; Decision making; Tooth fractures; Dental caries; Tooth extraction.

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