OBJECTIVES: The purpose of this study was to observe the change in the viscoelastic properties of thermoplasticized injectable root canal filling materials as a function of temperature and to compare the handling characteristics of these materials. MATERIALS AND METHODS: Three commercial gutta perchas and Resilon (Pentron Clinical Technologies) in a pellet form were heated in the Obtura-II system (Obtura Spartan) at 140degrees C and 200degrees C, and the extrusion temperature of the thermoplasticized materials was measured. The viscoelastic properties of the materials as a function of temperature were evaluated using a rheometer. The elastic modulus G', viscous modulus G", loss tangent tandelta, and complex viscosity eta* were determined. The phase transition temperature was determined by both the rheometer and a differential scanning calorimeter (DSC). The consistency of the materials was compared under compacting pressure at 60degrees C and 40degrees C by a squeeze test. RESULTS: The three gutta perchas had dissimilar profiles in viscoelastic properties with varying temperature. The phase transition of softened materials into solidification occurred at 40degrees C to 50degrees C, and the onset temperatures obtained by a rheometer and a DSC were similar to each other. The onset temperature of phase transition and the consistency upon compaction pressure were different among the materials (p < 0.05). Resilon had a rheologically similar pattern to the gutta perchas, and was featured between high and low-flow gutta perchas. CONCLUSIONS: The rheological characteristics of the thermoplasticized root canal filling materials changed under a cooling process. The dissimilar viscoelastic properties among the materials require different handling characteristics during an injecting and compacting procedure.
Elastic Modulus ; Gutta-Percha ; Handling (Psychology) ; Hot Temperature ; Phase Transition ; Root Canal Filling Materials ; Viscosity

This study aimed to assess whether the gender of the dental practitioner affects operative techniques in class 2 and class 5 resin composite restorations. In 2008, a nationwide survey was given to Korean dentists. Total 12,193 e-mails were distributed, 2,632 were opened by recipients, and 840 responses were collected. Of the respondents, 78.9% were male and 21.1% were female. The gender distribution in the age groups between respondents and the total population did not differ (p > 0.05). A chi-square test was used to compare technical differences between female and male dentists. A multiple logistic regression analysis was performed to assess the association between gender and operative techniques in resin composite restoration. For class 2 resin composite restoration, female dentists were 1.87 times more likely than male dentists to do multiple incremental fillings (four layers or more) and 2.72 times more likely than males to spend 30 minutes or more for the treatment (p < 0.05). For class 5 resin composite restoration, female dentists were 2.69 times more likely than their male counterparts to use a cavity base or liner, 1.83 times more likely to do multiple incremental fillings (four layers or more) and 1.63 times more likely to spend 20 minutes or more for the procedure (p < 0.05). The gender factor was influential to individual operative techniques in restorative treatment.
Surveys and Questionnaires ; Dentists ; Electronic Mail ; Female ; Humans ; Logistic Models ; Male

OBJECTIVES: The purpose of this study was to determine the effect of resin infiltration technique on color and surface hardness of white spot lesion (WSL) with various degrees of demineralization. MATERIALS AND METHODS: Ten human upper premolars were cut and divided into quarters with a 3 x 4 mm window on the enamel surface. Each specimens were separated into four groups (n = 10) and immersed in demineralization solution to create WSL: control, no treatment (baseline); 12 h, 12 hr demineralization; 24 h, 24 hr demineralization; 48 h, 48 hr demineralization. Resin infiltration was performed to the specimens using Icon (DMG). CIEL*a*b* color parameters of the enamel-dentin complex were determined using a spectroradiometer at baseline, after caries formation and after resin infiltration. Surface hardness was measured by Vickers Micro Hardness Tester (Shimadzu, HMV-2). The differences in color and hardness among the groups were analyzed with ANOVA followed by Tukey test. RESULTS: Resin infiltration induced color changes and increased the hardness of demineralized enamel. After resin infiltration, there was no difference in color change (DeltaE*) or microhardness among the groups (p < 0.05). CONCLUSION: There was no difference in the effect of resin infiltration on color and hardness among groups with different extents of demineralization.
Bicuspid ; Dental Caries ; Dental Enamel ; Hardness ; Hardness Tests ; Humans ; Nitriles ; Pyrethrins

OBJECTIVES: This study aimed to analyze the mineral composition of naturally- and artificially-produced caries-affected root dentin and to determine the elemental incorporation of resin-modified glass ionomer (RMGI) into the demineralized dentin. MATERIALS AND METHODS: Box-formed cavities were prepared on buccal and lingual root surfaces of sound human premolars (n = 15). One cavity was exposed to a microbial caries model using a strain of Streptococcus mutans. The other cavity was subjected to a chemical model under pH cycling. Premolars and molars with root surface caries were used as a natural caries model (n = 15). Outer caries lesion was removed using a carbide bur and a hand excavator under a dyeing technique and restored with RMGI (FujiII LC, GC Corp.). The weight percentages of calcium (Ca), phosphate (P), and strontium (Sr) and the widths of demineralized dentin were determined by electron probe microanalysis and compared among the groups using ANOVA and Tukey test (p < 0.05). RESULTS: There was a pattern of demineralization in all models, as visualized with scanning electron microscopy. Artificial models induced greater losses of Ca and P and larger widths of demineralized dentin than did a natural caries model (p < 0.05). Sr was diffused into the demineralized dentin layer from RMGI. CONCLUSIONS: Both microbial and chemical caries models produced similar patterns of mineral composition on the caries-affected dentin. However, the artificial lesions had a relatively larger extent of demineralization than did the natural lesions. RMGI was incorporated into the superficial layer of the caries-affected dentin.
Bicuspid ; Calcium ; Dentin* ; Electron Probe Microanalysis ; Glass ; Hand ; Humans ; Hydrogen-Ion Concentration ; Microscopy, Electron, Scanning ; Miners ; Models, Chemical ; Molar ; Root Caries ; Streptococcus mutans ; Strontium

The limited durability of resin-dentin bonds severely compromises the longevity of composite resin restorations. Resin-dentin bond degradation might occur via degradation of water-rich and resin sparse collagen matrices by host-derived matrix metalloproteinases (MMPs). This review article provides overview of current knowledge of the role of MMPs in dentin matrix degradation and four experimental strategies for extending the longevity of resin-dentin bonds. They include: (1) the use of broad-spectrum inhibitors of MMPs, (2) the use of cross-linking agents for silencing the activities of MMPs, (3) ethanol wet-bonding with hydrophobic resin, (4) biomimetic remineralization of water-filled collagen matrix. A combination of these strategies will be able to overcome the limitations in resin-dentin adhesion.
Biomimetics ; Chlorhexidine ; Collagen ; Dentin ; Ethanol ; Longevity ; Matrix Metalloproteinases

OBJECTIVES: Designing in situ models for caries research is a demanding procedure, as both clinical and laboratory parameters need to be incorporated in a single study. This study aimed to construct an informative guideline for planning in situ models relevant to preexisting caries studies. MATERIALS AND METHODS: An electronic literature search of the PubMed database was performed. A total 191 of full articles written in English were included and data were extracted from materials and methods. Multiple variables were analyzed in relation to the publication types, participant characteristics, specimen and appliance factors, and other conditions. Frequencies and percentages were displayed to summarize the data and the Pearson's chi-square test was used to assess a statistical significance (p < 0.05). RESULTS: There were many parameters commonly included in the majority of in situ models such as inclusion criteria, sample sizes, sample allocation methods, tooth types, intraoral appliance types, sterilization methods, study periods, outcome measures, experimental interventions, etc. Interrelationships existed between the main research topics and some parameters (outcome measures and sample allocation methods) among the evaluated articles. CONCLUSIONS: It will be possible to establish standardized in situ protocols according to the research topics. Furthermore, data collaboration from comparable studies would be enhanced by homogeneous study designs.
Cooperative Behavior ; Outcome Assessment (Health Care) ; Publications ; Sample Size ; Sterilization ; Tooth

BACKGROUND: The number of patients with Alzheimer's disease is growing worldwide, and the proportion of patients requiring dental treatment under general anesthesia increases with increasing severity of the disease. However, outpatient anesthesia management for these patients involves great risks, as most patients with Alzheimer's disease are old and may show reduced cardiopulmonary functions and have cognitive disorders. METHODS: This study retrospectively investigated 43 patients with Alzheimer's disease who received outpatient anesthesia for dental treatment between 2012–2017. Pre-anesthesia patient evaluation, dental treatment details, anesthetics dose, blood pressure, duration and procedure of anesthesia, and post-recovery management were analyzed and compared between patients who underwent general anesthesia or intravenous sedation. RESULTS: Mean age of patients was about 70 years; mean duration of Alzheimer's disease since diagnosis was 6.3 years. Severity was assessed using the global deterioration scale; 62.8% of patients were in level ≥ 6. Mean duration of anesthesia was 178 minutes for general anesthesia and 85 minutes for intravenous sedation. Mean recovery time was 65 minutes. Eleven patients underwent intravenous sedation using propofol, and 22/32 cases involved total intravenous anesthesia using propofol and remifentanil. Anesthesia was maintained with desflurane for other patients. While maintaining anesthesia, inotropic and atropine were used for eight and four patients, respectively. No patient developed postoperative delirium. All patients were discharged without complications. CONCLUSION: With appropriate anesthetic management, outpatient anesthesia was successfully performed without complications for dental treatment for patients with severe Alzheimer's disease.
Alzheimer Disease* ; Anesthesia* ; Anesthesia, General ; Anesthesia, Intravenous ; Anesthetics ; Atropine ; Blood Pressure ; Delirium ; Dementia ; Diagnosis ; Humans ; Outpatients* ; Propofol ; Retrospective Studies*

Spinal muscular atrophy (SMA) is an autosomal recessive, severe neuromuscular disorder in which degeneration of alpha motor neurons in the spine progressively weakens and ultimately paralyzes the proximal muscles. It occurs in one per 6,000-10,000 infants, and is a genetic disorder with the second-highest mortality rate worldwide. An 18-year-old male patient with SMA was referred for general anesthesia for difficulty in performing dental treatment due to limited mouth opening caused by temporomandibular joint (TMJ) pain. However, the patient had a high risk of general anesthesia complications, so TMJ pain during mouth opening was reduced through local anesthesia of the TMJ. Fortunately, the anesthesia was successful in reducing pain during mouth opening, enabling the patient to receive dental treatment with an adequate mouth opening.
Adolescent ; Anesthesia ; Anesthesia, General ; Anesthesia, Local* ; Dental Care for Disabled ; Humans ; Infant ; Male ; Mortality ; Motor Neurons ; Mouth* ; Muscles ; Muscular Atrophy, Spinal* ; Spine ; Temporomandibular Joint Disorders ; Temporomandibular Joint*

Spinal muscular atrophy (SMA) is an autosomal recessive, severe neuromuscular disorder in which degeneration of alpha motor neurons in the spine progressively weakens and ultimately paralyzes the proximal muscles. It occurs in one per 6,000-10,000 infants, and is a genetic disorder with the second-highest mortality rate worldwide. An 18-year-old male patient with SMA was referred for general anesthesia for difficulty in performing dental treatment due to limited mouth opening caused by temporomandibular joint (TMJ) pain. However, the patient had a high risk of general anesthesia complications, so TMJ pain during mouth opening was reduced through local anesthesia of the TMJ. Fortunately, the anesthesia was successful in reducing pain during mouth opening, enabling the patient to receive dental treatment with an adequate mouth opening.
Adolescent ; Anesthesia ; Anesthesia, General ; Anesthesia, Local* ; Dental Care for Disabled ; Humans ; Infant ; Male ; Mortality ; Motor Neurons ; Mouth* ; Muscles ; Muscular Atrophy, Spinal* ; Spine ; Temporomandibular Joint Disorders ; Temporomandibular Joint*

OBJECTIVES: This study evaluated the influence of a multi-mode universal adhesive (MUA) containing silane (Single Bond Universal, 3M EPSE) on the bonding of resin cement to lithium disilicate. MATERIALS AND METHODS: Thirty IPS e.max CAD specimens (Ivoclar Vivadent) were fabricated. The surfaces were treated as follows: Group A, adhesive that did not contain silane (ANS, Porcelain Bonding Resin, Bisco); Group B, silane (S) and ANS; Group C, hydrofluoric acid (HF), S, and ANS; Group D, MUA; Group E, HF and MUA. Dual-cure resin cement (NX3, Kerr) was applied and composite resin cylinders of 0.8 mm in diameter were placed on it before light polymerization. Bonded specimens were stored in water for 24 hours or underwent a 10,000 thermocycling process prior to microshear bond strength testing. The data were analyzed using multivariate analysis of variance (p < 0.05). RESULTS: Bond strength varied significantly among the groups (p < 0.05), except for Groups A and D. Group C showed the highest initial bond strength (27.1 ± 6.9 MPa), followed by Group E, Group B, Group D, and Group A. Thermocycling significantly reduced bond strength in Groups B, C, and E (p < 0.05). Bond strength in Group C was the highest regardless of the storage conditions (p < 0.05). CONCLUSIONS: Surface treatment of lithium disilicate using HF and silane increased the bond strength of resin cement. However, after thermocycling, the silane in MUA did not help achieve durable bond strength between lithium disilicate and resin cement, even when HF was applied.
Adhesives* ; Ceramics* ; Dental Porcelain ; Hydrofluoric Acid ; Lithium* ; Multivariate Analysis ; Polymerization ; Polymers ; Resin Cements ; Water