Journal of Dental Materials and Techniques
Volume:13 Issue: 1, Winter 2024

The purpose of this study was to investigate the effect of adding CPP-ACP into a daily-use toothpaste on the remineralization of enamel caries lesions. Thirty enamel blocks were obtained from bovine incisors. Each specimen was divided into three equal parts. One-third of each block was coated with varnish to serve as a sound control area, while the remaining two-thirds underwent a demineralization process. After demineralization, another one-third of the surface was varnished, leaving only one-third of the enamel to undergo remineralization. The enamel blocks were divided into three groups (n=10), according to the remineralization treatment applied as follows: Group 1: fluoride-containing toothpaste, Group 2: CPP-ACP-containing toothpaste, and Group 3: fluoride- and CPP–ACP–containing toothpaste.  Remineralization was assessed through the Vickers microhardness test at various depths (20, 50, 120 and 200 µm). The data were analyzed by ANOVA and LSD test, and P< 0.05 was considered statistically significant. There was a significant difference in remineralization efficacy between the groups at the depth of 20 µm (P 0.001). Pairwise comparisons revealed that the toothpaste containing both fluoride and CPP-ACP had a significantly greater microhardness than other experimental groups (P 0.05). No significant difference was observed between the study groups concerning microhardness at 50, 120 and 200 µm depths (P 0.05). CPP-ACP can serve as a suitable alternative to fluoride in daily-use toothpaste for enamel remineralization. The concurrent use of fluoride and CPP-ACP in toothpaste can generate a synergistic remineralizing effect at the enamel surface layer.

Proper and conservative endodontic access cavity preparation is a crucial step in performing a successful root canal treatment that ensures a long-term prognosis. This study aimed to evaluate the intercuspal and interorifice length of maxillary first and second molars using cone beam computed tomography (CBCT).

The CBCT scans of 400 mature and intact maxillary first and second molars (16, 17, 26, and 27) were evaluated. The measured variables included the distances between the buccal cusps (intercuspal distance) and buccal orifices (interorifice distance), the interorifice/intercuspal ratio, and the angle at the intersection of interorifice and intercuspal lines. The variables were compared between different teeth and between male and female patients.

The interorifice and intercuspal distances were significantly greater in males compared to females (P<0.05), except for the intercuspal distance in the left maxillary second molar (P=0.056). There was a statistically significant difference concerning the angle formed between the interorifice and intercuspal lines among tooth numbers 26 and 27 (P=0.044). The interorifice/intercuspal ratio was significantly different between the maxillary first and second molars on the right (P=0.006) and left sides (P<0.001).

The angle formed between the intercuspal and interorifice distances and the interorifice/ intercuspal ratio was greater in the maxillary first molars compared to the second molars. Moreover, males generally had larger internal and external anatomical features than females. Hence, when preparing a conservative access cavity in maxillary molars, clinicians are advised to consider both the external tooth anatomy and the patient's gender as important factors

This study aimed to evaluate the effect of different premedication protocols on the success rate of the inferior alveolar nerve block (IANB) technique in mandibular molars with irreversible pulpitis. Two hundred and ten participants were randomly assigned into three groups (n=70) and received one of the following premedications 30 minutes before IANB injection: dexamethasone, pharmapain (containing acetaminophen, ibuprofen, and caffeine), and a placebo lactose capsule. Pain severity was evaluated with the Heft–Parker visual analog scale (VAS) before and 15 minutes after the injection, during dentin removal, and when inserting files into the root canal. The IANB injection was considered successful if VAS values after 15 minutes implied no pain or mild pain.  IANB success rates were comparable in the dexamethasone (51.4%), pharmapain (55.7%), and placebo (41.4%) groups (P=0.222). Pain severity at baseline, 15 minutes post-injection, and during dentin removal was comparable among the groups (P>0.05). However, when inserting endodontic files, the mean pain severity in the pharmapain group was significantly higher than the dexamethasone group (10.27 ± 1.71 versus 7.38 ± 2.24; P=0.002). No significant difference was observed between the placebo with any of the study groups (P>0.05). Premedication with pharmapain (an anti-inflammatory agent) or dexamethasone (a corticosteroid) does not enhance the success rate of the IANB technique in mandibular molars with irreversible pulpitis compared to placebo. However, the use of dexamethasone was significantly more effective than pharmapain in reducing pain severity at inserting endodontic files.

This study aimed to evaluate the effect of different recycling (also known as reconditioning) methods on the shear bond strength (SBS) of ceramic brackets. Fifty mechanically retentive polycrystalline ceramic brackets and 50 mandibular bicuspids were used in this study. The teeth were divided into 5 groups and bonded with new (group 1) or reconditioned brackets. The reconditioning methods were sandblasting (group 2), sandblasting + silane (group 3), hydrofluoric (HF) acid + silane (group 4), and Er:YAG laser (group 5). The SBS of brackets were assessed and the adhesive remnant index (ARI) scores were determined. Statistical analysis was performed using one-way ANOVA, Tukey, and chi-square tests at P<0.05. The highest SBS value was observed in brackets treated with sandblasting + silane (19.26 ± 3.30 MPa), which was comparable to both the control (19.01 ± 3.12 MPa) and sandblasting (16.98 ± 3.13 MPa) groups. Treatment with hydrofluoric acid + silane (9.46 ± 3.43 MPa) and Er:YAG laser (9.71 ± 1.23 MPa) yielded significantly lower SBS values than the other study groups (P<0.05). The highest overall ARI scores were observed in the HF acid + silane and Er:YAG laser group, indicating more adhesive remnants on the enamel surface. Sandblasting, with or without silane treatment, effectively restored the bond strength of ceramic brackets to almost initial values. Although recycling with hydrofluoric acid + silane or Er:YAG laser produced lower bond strengths, they still surpassed the clinical threshold of 7.8 MPa, making them viable options for bracket reconditioning in clinical settings.

The present study aimed to evaluate the bond strength of Sure-Seal Root as a new bioceramic-based sealer, and compare it with other sealers, including an epoxy resin-based sealer (AH-Plus), zinc oxide eugenol (ZOE) and a mineral trioxide aggregate-based sealer (MTA Fillapex).

In this in vitro study, 40 extracted mandibular premolars were randomly assigned into 4 groups (n=10) according to the type of sealer applied as follows: Group 1: AH-Plus, Group 2: MTA-Fillapex, Group 3:  Sure-Seal Root, and Group 4: ZOE. The canals were prepared and obturated with gutta-percha and the corresponding sealer. The samples were sectioned into horizontal segments, and the push-out bond strength was determined using a universal testing machine at the coronal, middle, and apical root thirds. The data were analyzed by repeated measures ANOVA, and the significance level was set at P<0.05.

There were no significant differences in the push-out bond strength between groups in the coronal third (P>0.05). In the middle third, AH-Plus exhibited significantly greater bond strength compared to Sure-Seal Root and ZOE sealers (P<0.05), whereas MTA-Fillapex was not significantly different from the other groups (P>0.05). In the apical third, both AH-Plus and MTA-Fillapex showed significantly greater push-out bond strength than Sure-Seal Root and ZOE sealers (P<0.05).

AH-Plus sealer exhibited the highest and ZOE showed the lowest bond strength. Sure-Seal Root indicated promising bond strength results when compared to ZOE and MTA-Fillapex. The push-out bond strength of all sealers to dentin increased from the coronal to the apical third.

Some endodontic procedures require using intracanal medicament between treatment sessions. The effectiveness of these agents on dentin microhardness is crucial for deciding whether to use them or not. This study aimed to compare the effectiveness of three intracanal medicaments including Triphala, calcium hydroxide (Ca(OH)2) paste, and chlorhexidine (CHX) gel on the root dentin microhardness. Forty-eight single canal mature permanent teeth were selected. Mechanical preparation was done using RaCe rotary files. The samples were randomly allocated to four equal groups (n=12), according to the applied intracanal medicament. Group 1 received no medicament, whereas the root canals in groups 2, 3, and 4 were filled with Triphala, Ca(OH)2, and CHX, respectively. Specimens were stored for one week.  Then, the roots were sectioned and the Vickers microhardness value was recorded at 0.5 mm from the pulp–dentin interface. Data were analyzed by one-way ANOVA and Tukey test and a P-value < 0.05 was considered statistically significant. The mean microhardness values in the Triphala and calcium hydroxide groups were comparable to each other (P>0.05) and significantly lower compared to the control and CHX groups (P<0.05). No significant difference in microhardness was found between the CHX and control groups (P>0.05). Triphala and Ca(OH)2 had similar effects on root dentin microhardness. Given the favorable characteristics of Triphala medicament, it can be considered a suitable alternative to Ca(OH)2 for intracanal application.

This study aimed to assess the staining susceptibility of the hybrid layer remaining on the enamel surface after bracket removal, focusing on various bonding agents applied for the bonding process. A total of 120 enamel discs were obtained from bovine incisors. The specimens were divided into 5 groups (n=24) according to the bonding agent applied, as follows: Group 1: Control, Group 2: Transbond XT, Group 3: Proseal, Group 4: Icon + Transbond XT, and Group 5: Icon + Heliobond. After composite removal, half of the specimens were exposed to a tea solution and the other half to a tea + citric acid solution (n=12). The “L”, “a”, and “b” color components were spectrophotometrically assessed at various stages including pre-bonding (T1), after debonding (T2), and after 24-hour immersion in the discoloration solution (T3). The color changes (ΔL, Δa, Δb) were analyzed by a two-way ANOVA at P<0.05. In all groups, a small shift in all color components was observed after debonding and polishing the surface. All groups showed similar, noticeable color changes after exposure to the discoloration solutions. Neither the type of bonding agent nor the type of staining solution had a significant influence on ΔL, Δa, and Δb values between different treatment stages (P>0.05 for all comparisons). Despite enamel polishing, some discolorations remain on the enamel after debonding, possibly due to the primers applied during bracket bonding. The type of bonding agent and the staining solution does not significantly affect the color stability of teeth after debonding.

This study aimed to compare the precision of a temporomandibular joint (TMJ)-related bite-registration technique with the occlusion-related registration technique using various polyvinyl siloxane materials.  The interocclusal relation of 40 patients was transferred to stone casts by bite registrations using polyvinyl siloxane materials with different Shore harnesses (SH) values including Registrado clear (SH=70 A), Registrado xtra (SH=51 D) and Registrado scan (SH=90A). A joint-related registration technique (called the Gerber technique or gothic arch tracing) was also applied in all patents. The clinical contact situation and the contacts on stone casts were marked and transferred to a 3D-measuring software. The deviation of the occlusal contacts on the stone casts to the clinical reference was measured and compared between the registration methods.   There was no statistically significant difference in contact deviation values between different types of registration methods (P=0.093). However, the frequency of missing contacts was significantly greater in the Gerber technique compared to the occlusion-related bite registrations (P<0.001). Gerber technique revealed greater deviations of the contact points in subjects with pain in TMJ and masticatory muscles. Irrespective of the registration technique, the patient-related factors including orthodontic pretreatment, treatment of TMD with occlusal splints, pain on palpation, joint noises, and restricted mandibular movement did not significantly affect the degree of occlusal contact deviation (P>0.05). The hardness of the polyvinyl siloxane materials for occlusion-related bite registration did not affect the precision of the registration techniques in dentulous patients. Polyvinyl siloxane materials should be preferred for joint-related registration in TMD patients