Comparing volumetric and biological aspects of 3D-printed interim restorations under various post-curing modes

Purpose@#This study aims to compare the volumetric change, degree of conversion (DOC), and cytotoxicity of 3D-printed restorations post-cured under three different conditions. Materials and Methods: 3D-printed interim restorations were post-cured under three different conditions and systems: 5 min, 30 min, and 24 h. Three-unit and six-unit fixed dental prostheses (n = 30 for each case) were printed; ten specimens from each group were post-cured and then scanned to compare their volumetric changes. Root-mean-squared (RMS) values of the data were acquired by superimposing the scanned files with original files.Thirty disk-shaped specimens were printed to evaluate the DOC ratio. Fourier transform infrared spectroscopy was used to compare the DOCs of 10 specimens from each group. Human gingival fibroblasts were used to measure the cell viability of every specimen (n = 7). The data from this experiment were employed for one-way analysis of variance and Tukey’s post-hoc comparisons. @*Results@#Differences between the three-unit restorations were statistically insignificant, regardless of the post-curing conditions. However, for the six-unit restorations, a high RMS value was acquired when the post-curing duration was 30 min. The average DOC was approximately 56 - 62%; the difference between each group was statistically insignificant. All the groups exhibited cell viability greater than 70%, rendering them clinically acceptable. @*Conclusion@#The post-curing conditions influenced the volume when the length of the restoration was increased. However, this deviation was found to be clinically acceptable. Additionally, postcuring did not significantly influence the DOC and cytotoxicity of the restorations.

Comparing volumetric and biological aspects of 3D-printed interim restorations under various post-curing modes

Purpose@#This study aims to compare the volumetric change, degree of conversion (DOC), and cytotoxicity of 3D-printed restorations post-cured under three different conditions. Materials and Methods: 3D-printed interim restorations were post-cured under three different conditions and systems: 5 min, 30 min, and 24 h. Three-unit and six-unit fixed dental prostheses (n = 30 for each case) were printed; ten specimens from each group were post-cured and then scanned to compare their volumetric changes. Root-mean-squared (RMS) values of the data were acquired by superimposing the scanned files with original files.Thirty disk-shaped specimens were printed to evaluate the DOC ratio. Fourier transform infrared spectroscopy was used to compare the DOCs of 10 specimens from each group. Human gingival fibroblasts were used to measure the cell viability of every specimen (n = 7). The data from this experiment were employed for one-way analysis of variance and Tukey’s post-hoc comparisons. @*Results@#Differences between the three-unit restorations were statistically insignificant, regardless of the post-curing conditions. However, for the six-unit restorations, a high RMS value was acquired when the post-curing duration was 30 min. The average DOC was approximately 56 - 62%; the difference between each group was statistically insignificant. All the groups exhibited cell viability greater than 70%, rendering them clinically acceptable. @*Conclusion@#The post-curing conditions influenced the volume when the length of the restoration was increased. However, this deviation was found to be clinically acceptable. Additionally, postcuring did not significantly influence the DOC and cytotoxicity of the restorations.

Conservative approach for anterior crown-root fractured teeth: forced eruption

In the case of crown-root fracture due to traumatic injury in anterior tooth and the fracture margin is located subgingivally,forced eruption has been proposed for the reconstruction of deficient bone and soft tissue. Forced eruption is one of the easiestorthodontic approaches that can have an acceptable outcome and prognosis, and has a low incidence of relapse. However, using heavy forces or very fast movements can also cause tissue damage or ankylosis. The following case reports present forced eruption as treatment option of crown fracture in maxillary anterior teeth.

Conservative approach for anterior crown-root fractured teeth: forced eruption

In the case of crown-root fracture due to traumatic injury in anterior tooth and the fracture margin is located subgingivally,forced eruption has been proposed for the reconstruction of deficient bone and soft tissue. Forced eruption is one of the easiestorthodontic approaches that can have an acceptable outcome and prognosis, and has a low incidence of relapse. However, using heavy forces or very fast movements can also cause tissue damage or ankylosis. The following case reports present forced eruption as treatment option of crown fracture in maxillary anterior teeth.

A literature review on burning mouth syndrome

Burning mouth syndrome (BMS) is defined as the xerostomia, burning sensation and various discomfort of tongue and oral mucosa. BMS can occur in both men and women, but is more frequent in middle-aged menopausal women. Because exact cause can't be identified clearly and it is hard to make diagnosis in clinic, the purpose of the treatment have been to relieve symptoms. Etiology of BMS is divided into local, systemic, and psychological factors. α-lipoic acid, clonazepam, supplemental therapy and cognitive behavior therapy can be prescribed for BMS. Nowdays, many experts focus attention on effect of combination therapy. It is necessary to solve the symptoms of the patients by combination of pharmacological approach and psychotherapy with cognitive behavior therapy considering the factors in various aspects.

Evaluation of the color stability of light cured composite resins according to the resin matrices / 대한치과재료학회지

The purpose of this study was to evaluate the color stability of light cured composite resins according to the resin matrices. Three kinds of resin matrices such as Bis-GMA (Venus® Diamond; VD), Silorane (FiltekTM P90; P90), and Ormocer (Admira; Ad) were selected. Each of them were used to prepare 30 specimens. The initial CIE L*a*b* values were measured by means of a Spectrophotometer (NF999, Nippon Denshoku, Japan). For accelerated aging process, the specimens were immersed in a circulating water bath with distilled water at 60℃. Spectrophotometric analyses were made after immersion of 8, 16, 24, 41 days and the color difference (ΔE*) was calculated. The L* value increased compared with initial L* value. VD had the greatest L* value change and Ad had the smallest L* value change (p<0.05). Ad had the greatest a* value change and VD had the smallest a* value change (p<0.05). The b* value of P90 increased steadily in positive value (+)(p<0.05). ΔE* of Ad had the smallest value and that of P90 had the greatest change with time. According to this study, the value of light cured composite resins was increased with water sorption and color of those changed into greenish and yellowish. And according to the evaluation of color stability, Ad with Ormocer as resin matrices had the best color stability with time in oral environment and P90 with Silorane as resin matrices had the lowest color stability with time. And VD had the greatest initial ΔE*.

Effects of various root canal sealers on tooth discoloration and internal bleaching / 대한치과재료학회지

There are several causes of tooth discoloration following root canal treatment. In this study, we evaluated the effects of sealers on tooth discoloration and internal bleaching. Twenty-four teeth were divided into 4 groups: control group, AH plus, Endosequece BC, and MTA fillapex group. Root canal filling was performed using each sealer conventionally and non-vital bleaching was performed with sodium perborate. The L, a, and b values were measured using Vita easyshade. Tooth discoloration after root canal treatment occurs irrespective of the type of sealers and may cause discoloration with only gutta-percha cone. The effect of non-vital bleaching following the use of calcium silicate-based sealers such as Endosequece BC and MTA fillapex was higher than that of AH plus. Therefore, it needs careful use of sealers in endodontics and calcium silicate-based sealers have advantages of bleaching in case of discolored tooth.

Influence of light-curing on the translucence change and color stability of amine-free dual-cured resin cements / 대한치과재료학회지

The aim of this study was to investigate the influence of light-curing on the translucency change and color-stability of amine(tertiary)-free dual-cured resin cements after accelerated aging. Two curing modes (dual-curing and self-curing) were applied on three dual-cured resin cements (Duo-Link Universal [DLU], Nexus Third Generation [NX3] and RelyX Ultimate [RXU]) in this study. Ten specimens were fabricated for each group. In dual-cured groups only, light-activation was performed with polywave-LED curing unit (Bluphase, Ivoclar Vivadent, Schaan, Liechtenstein), where each sides of the samples were photo-polymerized for 60 seconds. Self-cured groups were kept in the dark storage for 24 hours. The color of the specimens was measured with spectrocolorimeter (NF999, Nippon Denshoku, Japan) after 24 hours of making samples. After the initial color measurements, the specimens were subjected to accelerated aging procedure. Spectrophotometric analysis was carried out on day 7, day 14, day 21 and day 28 of accelerated aging in 60 ℃ of distilled water. The color characteristics, color difference (ΔE*), and translucency parameter (TP) of specimens were calculated according to the CIE L*a*b* color system before and after aging. All the ΔE* values and TP values were analyzed by 2-way analysis of variance. After aging, all groups revealed clinically perceptible color differences (ΔE*>3.3). Differences in ΔE* values of self-cured groups were significantly higher than those of dual-cured groups in NX3 and RXU. But there were no significant differences in ΔE* between dual-cured mode and self-cured mode of DLU. All mean b* values increased after aging. All mean L* values decreased after aging except for self-cured RXU cement. TP values also decreased with aging. TP values of self-cured groups were significantly lower than those of dual-cured groups in NX3 and RXU. Hence, in conclusion, despite the absence of tertiary amine in the dual-cured resin cements, such resin cements should be polymerized with the dual-cure modes to ensure long-term color-stability.

Oral manifestation and root canal therapy of the patient with mucopolysaccharidosis

Mucopolysaccharidosis (MPS) is an inherited metabolic disorder caused by a deficiency in enzymes that participate in the degradation of glycosaminoglycans (GAGs) such as heparin sulfate and dermatan sulfate. Left untreated, patients show progressive mental and physical deterioration due to deposition of GAGs in organs. Death often occurs due to cardiac or respiratory failure before patients reach their early twenties. MPS has several oral and dental manifestations. An enlarged head, short neck, and open mouth associated with a large tongue are major characteristics of MPS patients. Dental complications can be severe, including unerupted dentition, dentigerous cyst-like follicles, malocclusions, condylar defects, and gingival hyperplasia. A 21-year-old female patient with MPS was described in this article, with special emphasis on oral manifestations and dental treatment.

Effects of RetroMTA on osteoblastic differentiation in MC3T3-E1 cells / 대한치과재료학회지

Mineral trioxide aggregate (MTA) provides a very good sealing, acceptable biocompatibility, dentin bridge formation and osteo-inductive effect. However, MTA has a few drawbacks. RetroMTA including calcium-zirconia complex has been developed to overcome drawbacks of MTA, especially long setting time and difficult handling characteristics. Therefore, the aim of this study was to evaluate the effects of RetroMTA on biocompatibility, osteogenic differentiation and mineralization in MC3T3-E1 cells compared with conventional MTA. Cytotoxicity was assessed by WST-1 assay. The gene expression of osteogenic markers was detected by real-time PCR. ALP activity and mineralization behavior were evaluated using ALP and alizarin red staining. There was no statistically significant difference between ProRoot MTA and RetroMTA with material extracts at dilutions of 1/4, 1/10 and 1/50 in cell viability assay. Expression of osteogenic markers in both ProRoot MTA and RetroMTA groups was significantly higher than in control group. In the mineralization assay, RetroMTA showed significantly higher formation of mineralized nodules than in control. In conclusion, RetroMTA promotes osteogenic differentiation and potential mineralization. It appears to be a potential alternative to ProRoot MTA as a root-end filling material.