Dentin wear after simulated toothbrushing with water, a liquid dentifrice or a standard toothpaste.

PURPOSE: To investigate the influence of dentifrices with and without abrasives on the wear and surface topography of human dentin following simulated toothbrushing in vitro. METHODS: 24 dentin specimens were prepared and randomly allocated to a liquid dentifrice (Garglin Gum-Guard), conventional dentifrice (333 Clinic Total Care), and control (distilled water) groups. Specimens were subjected to simulated toothbrushing of 50,000 repeated strokes under a 150 g-load. The dentin surface was profiled in each specimen using a profilometer before and after toothbrushing. The mean surface roughness (Ra) of the specimens was calculated and compared by one-way ANOVA and Tukey's post-hoc test (α = 0.05). The dentin surfaces were further examined by scanning electron microscopy (SEM). RESULTS: The Ra values were similar between the liquid dentifrice and control groups (P > 0.05), and was significantly higher in the conventional dentifrice group (P < 0.001). On SEM examination, patent dentin tubules were observed in the conventional dentifrice and liquid dentifrice groups, but were not observed in the control group.

Influence of Dentoalveolar Ankylosis on the Biomechanical Response of a Single-rooted Tooth and Surrounding Alveolar Bone: A 3-dimensional Finite Element Analysis.

INTRODUCTION: Dentoalveolar ankylosis necessarily accompanies the loss of periodontal ligament (PDL), which might alter the biomechanical response of the tooth. The purpose of this study was to investigate the influence of dentoalveolar ankylosis on a single-rooted tooth and the surrounding alveolar bone structures in the biomechanical standpoint. METHODS: A basic model of an intact maxillary central incisor and the surrounding bone structures was chosen for the numeric analysis. From this basic model, 6 different models were further developed by combining 3 types of endodontic status (an intact model, a nonsurgically treated model, and a surgically treated model) and 2 types of periodontal attachment condition (models with or without PDL). For each condition, maximum von Mises stress (σ max) in dentin and bone and maximum tooth displacement (ΔR max) were calculated. RESULTS: In models with dentoalveolar ankylosis, stress was concentrated on the cervical dentin around the cementoenamel junction and the alveolar bone crest, whereas the stress was more evenly distributed along the entire length of the root in models with normal PDL. The models with dentoalveolar ankylosis showed higher stress values in dentin (44.72%-80.56% of σ max increase) and bone (24.23%-80.68% of σ max increase) and lower tooth displacement (59.22%-63.97% of ΔR max decrease) compared with the models with normal PDL. CONCLUSIONS: Dentoalveolar ankylosis exerts significant changes on the biomechanical response of a single-rooted tooth and the surrounding bone structures. The dentoalveolar complex with ankylosis showed characteristic stress concentrations, increased stress values, and decreased tooth displacement compared with that with normal PDL.

Survival Rate of Teeth with a C-shaped Canal after Intentional Replantation: A Study of 41 Cases for up to 11 Years.

INTRODUCTION: Teeth with a C-shaped canal have been regarded as a challenge for nonsurgical root canal treatment (RCT) and apical microsurgery because of their anatomic variations and low accessibility. For such teeth, intentional replantation might be a treatment option. The purpose of this study was to investigate the prognostic factors for the clinical outcome of intentionally replanted teeth with a C-shaped canal. METHODS: We retrospectively investigated patients who had undergone intentional tooth replantation at the Department of Conservative Dentistry, Yonsei University Dental Hospital, Seoul, Korea, from June 2002 to November 2015. Consequently, 41 intentionally replanted teeth with C-shaped canals were identified. The cumulative survival rate and related prognostic factors were assessed based on clinical and radiographic examination using survival analysis. RESULTS: The cumulative survival rate of intentionally replanted teeth with a C-shaped canal was 83.4% at 4 years and 73.0% at 11 years postoperatively. Based on Cox proportional hazard regression analysis, extraoral time (≤15 minutes vs >15 minutes) and retrofilling material (ProRoot MTA [Dentsply, Tulsa, OK] vs others) were significantly associated with tooth survival (P < .05). CONCLUSIONS: Extraoral time exceeding 15 minutes and the use of ProRoot MTA as a retrofilling material were significantly associated with a lower survival of intentionally replanted teeth with C-shaped canals. With improved clinical procedures based on an understanding of the prognostic factors, intentional replantation would be a favorable treatment option for treating teeth with a C-shaped canal.

Prognostic Factors for Clinical Outcomes in Autotransplantation of Teeth with Complete Root Formation: Survival Analysis for up to 12 Years.

INTRODUCTION: Tooth autotransplantation is a treatment option that has the potential to restore masticatory function and esthetics to edentulous spaces resulting from extracted teeth. The purpose of this study was to investigate the prognostic factors and clinical outcomes for autotransplanted teeth with complete root formation. METHODS: Patients who had received tooth autotransplantation in the Department of Conservative Dentistry, Yonsei University Dental Hospital, Seoul, Korea, from July 2001 to August 2010 were electronically searched, and a total of 105 cases of autotransplanted teeth met the inclusion criteria. Tooth survival, inflammatory root resorption (IRR), ankylosis, and related prognostic factors were assessed by using the survival analysis that was based on clinical and radiographic examination. RESULTS: The cumulative tooth survival rate was 68.2% at 12 years after the tooth autotransplantation. According to the Cox proportional hazard regression analysis, patient age, donor position, and extraoral time were significantly associated with tooth survival (P < .05). Donor extraction type was significantly associated with IRR (P < .05), and transplantation timing and initial stability were significantly associated with ankylosis (P < .05) CONCLUSIONS: Patients less than 45 years of age, maxillary donor teeth, and an extraoral time of less than 15 minutes were associated with significantly higher tooth survival. Surgical extraction of the donor tooth was associated with a significantly higher incidence of IRR. Immediate transplantation after the extraction of the recipient site's tooth and low initial stability were associated with a significantly lower incidence of ankylosis.

Influence of apical root resection on the biomechanical response of a single-rooted tooth-part 2: apical root resection combined with periodontal bone loss.

INTRODUCTION: In a clinical situation, an apically resected tooth is often accompanied by a varying degree of periodontal bone loss. The purpose of this study was to assess the influence of apical root resection combined with periodontal bone loss on the biomechanical response of a single-rooted tooth. METHODS: A basic intact model and a basic apically resected model of the upper central incisor were selected for the numerical analysis. From each basic model, 6 models were developed assuming different amounts of periodontal bone loss (0, 0.5, 1, 1.5, 2, and 3 mm). Maximum von Mises stress (σ max), maximum tooth displacement (ΔR max), and effective crown-to-root ratio (α) were calculated for each condition. RESULTS: There were only marginal differences (a 2.1% difference in σ max and a 16.9% difference in ΔR max) between the biomechanical responses of the intact model and the apically resected model when the tooth was supported by a normal periodontium. However, when destruction of the periodontium was assumed, the intact model and the apically resected model responded differently. The difference increased as the periodontal bone loss progressed, resulting in a 68.7% difference in σ max and a 56.3% difference in ΔR max when the periodontal bone loss increased to 3 mm (α = 0.48). CONCLUSIONS: Although the biomechanical response of an apically resected tooth was relatively stable when the tooth was supported by a normal periodontium, the apically resected tooth showed a more deteriorated response compared with the intact tooth as the periodontal bone loss progressed.

A Randomized Controlled Study of the Use of ProRoot Mineral Trioxide Aggregate and Endocem as Direct Pulp Capping Materials: 3-month versus 1-year Outcomes.

INTRODUCTION: The purpose of this study was to assess the long-term clinical outcomes of direct pulp capping (DPC) with ProRoot MTA (Dentsply, Tulsa, OK) and Endocem (Maruchi, Wonju, Korea) as pulp capping materials. To this end, the 1-year cumulative successes of both materials were evaluated and compared with those of the 3-month outcomes in a prospective, randomized controlled trial. METHODS: Patients were recruited from the Department of Conservative Dentistry of the Yonsei University Dental Hospital, Seoul, South Korea, from January to May 2013. Of the 48 teeth that met the inclusion criteria, 46 teeth were randomly allocated to either ProRoot MTA or Endocem groups (n = 23). Direct pulp capping was performed, and clinical and radiographic examinations were conducted over 1 year after the treatment. Survival analyses were conducted to compare the cumulative successes between ProRoot MTA and Endocem and to evaluate other clinical variables. RESULTS: Forty-one teeth were recalled 1 year after the treatments (recall rate = 89.13%). There were no significant differences between the cumulative successes of ProRoot MTA and Endocem in either log-rank or Cox proportional hazard regression analyses (P > .05). Among the other clinical variables, cavity type (class I, II, III vs class V) was determined to be significant in both the log-rank test (P = .001) and Cox regression analysis (P = .006). CONCLUSIONS: Both ProRoot MTA and Endocem exhibited similar cumulative successes as direct pulp capping materials up to 1 year. The teeth restored with class V cavities exhibited significantly lower cumulative success rates after direct pulp capping compared with the teeth restored with other types of cavities.

Influence of apical root resection on the biomechanical response of a single-rooted tooth: a 3-dimensional finite element analysis.

INTRODUCTION: Apical root resection is a biologically essential component in endodontic microsurgery. However, because it reduces the total root length and supported root surface, it changes the biomechanical response of the tooth. The purpose of this study was to analyze the biomechanical effect of apical root resection and to compare apical root resection with periodontal bone loss from a biomechanical standpoint. METHODS: Finite element models of the maxillary central incisor were reconstructed. First, preoperative and surgically treated models were generated to assess the factors altering the biomechanical response of the tooth. Then, apically resected models with different amounts of resection (3, 4, 5, 6, 7, and 8 mm) were created to estimate the clinically applicable limit of apical root resection. Periodontally destructed models with varying degrees of bone loss (0.5, 1, 1.5, 2, and 3 mm) were also created to compare the effect of apical root resection with periodontal bone loss. Stress distribution, tooth displacement, and effective crown-to-root ratio (α) were analyzed for each condition. RESULTS: Apical root resection did not significantly alter the maximum von Mises stress or tooth displacement until it reached 6 mm (α = 0.67) when the tooth was supported by normal periodontium. In contrast, periodontal bone loss had a greater impact on biomechanical response change compared with apical root resection. CONCLUSIONS: For a tooth supported by normal periodontium, 3 mm of apical root resection (α = 1.07) appeared to be mechanically acceptable. The biomechanical influence of apical root resection was weak compared with that of periodontal bone loss.

Biologic response of local hemostatic agents used in endodontic microsurgery.

Appropriate use of local hemostatic agent is one of the important factors on the prognosis of endodontic microsurgery. However, most investigations to date focus on the hemostatic efficacy of the agents, whereas their biologic characteristics have not received enough attention. The purpose of this paper was to review the biologic response of local hemostatic agents, and to provide clinical guidelines on their use during endodontic microsurgery. Electronic database (PUBMED) was screened to search related studies from 1980 to 2013, and 8 clinical studies and 18 animal studies were identified. Among the materials used in these studies, most widely-investigated and used materials, epinephrine, ferric sulfate (FS) and calcium sulfate (CS), were thoroughly discussed. Influence of these materials on local tissue and systemic condition, such as inflammatory and foreign body reaction, local ischemia, dyspigmentation, delayed or enhanced bone and soft tissue healing, and potential cardiovascular complications were assessed. Additionally, biological property of their carrier materials, cotton pellet and absorbable collagen, were also discussed. Clinicians should be aware of the biologic properties of local hemostatic agents and their carrier materials, and should pay attention to the potential complications when using them in endodontic microsurgery.

Cardiovascular effect of epinephrine in endodontic microsurgery: a review.

Epinephrine is one of the most widely-used vasoconstrictors in dental treatment including endodontic microsurgery. However, the systemic safety of epinephrine has been in debate for many years because of its potential risk to cause cardiovascular complications. The purpose of this review was to assess the cardiovascular effect of epinephrine use in endodontic microsurgery. Endodontic microsurgery directly applies epinephrine into the bone cavity, and the amount is reported to be much larger than other dental surgeries. Moreover, when considering that systemic potency of intraosseous application is reported to be comparable to intravenous application, the systemic influence of epinephrine could be increased in endodontic microsurgery. Besides, pre-existing cardiovascular complications or drug interactions can enhance its systemic influence, resulting in increased susceptibility to cardiovascular complications. Although clinical studies have not reported significant complications for patients without severe systemic complications, many epinephrine-induced emergency cases are warning the cardiovascular risk related with pre-existing systemic disease or drug interactions. Epinephrine is a dose-sensitive drug, and its hypersensitivity reaction can be fatal to patients when it is related to cardiovascular complications. Therefore, clinicians should recognize the risk, and the usage of pre-operative patient evaluation, dose control and patient monitoring are required to ensure patient's safety during endodontic microsurgery.