Specimen Shape and Elution Time Affect the Mineralization and Differentiation Potential of Dental Pulp Stem Cells to Biodentine.

The liquid extract method is commonly used to evaluate the cytotoxicity and bioactivity of materials. Although ISO has recommended guidelines for test methods, variations in elution period, and shape of samples can influence the biological outcomes. The aim of this study was to investigate the influence of material form and elution period of Biodentine on dental pulp stem cells (DPSCs)' proliferation and mineralization. Biodentine (0.2 g) discs or powder were immersed in culture media (10 mL) for 1, 3 or 7 days (D1, D3 and D7). The eluents were filtered and used to treat DPSC. The calcium release profile and pH were determined. Cell proliferation was evaluated by MTS for 3 days, and mineralization and differentiation were assessed by alizarin red S staining (Ca2+/ng of DNA) and qRT-PCR (MEPE, DSPP, DMP-1, RUNX2, COL-I and OCN) for 14 days. Statistical analysis was performed with a one or two-way ANOVA and post hoc Tukey's test (pH, calcium release and proliferation) or Mann-Whitney test (α = 0.05). pH and calcium ion release of powdered eluents were significantly higher than disc eluents. Powdered eluent promoted extensive cell death, while the disc form was cytocompatible. All disc eluents significantly increased the gene expression and mineralization after 14 days compared to the untreated control. D7 induced less mineralization and differentiation compared to D1 and D3. Thus, the materials' form and elution time are critical aspects to be considered when evaluating the bioactivity of materials, since this binomial can affect positively and negatively the biological outcomes.

Long-term Success and Survival of Endodontic Microsurgery.

INTRODUCTION: Healed rates of endodontic microsurgery (EMS) may decrease over time, but research on the long-term outcomes is scarce. The aims of this retrospective cohort study were to evaluate the 5- to 9-year healed and survival rates of EMS, to identify associations between prognostic factors and healing status, and to compare the short-term (1- to 2-year) with long-term (5- to 9-year) outcomes. METHODS: One hundred fifty-one eligible patients (166 teeth) who underwent EMS in 2007-2010 were invited for a follow-up examination. Eighty-three patients (94 teeth) participated in the study. Survival status and reasons for extraction of all teeth were determined, and survival rates were calculated by Kaplan-Meier analyses. Outcomes were determined on the basis of clinical and radiographic findings and associated with potential prognostic variables via multivariate Cox regression analyses. RESULTS: Thirty-two teeth were extracted: 6 because of endodontic failure, 20 for unrelated reasons, and 6 for unknown reasons. Outcomes were categorized as healed and not healed. Multivariate analysis revealed that adjusted hazard ratio for failure was 5.95 times higher (95% confidence interval, 1.54-22.91) for teeth treated with intermediate restorative material than with mineral trioxide aggregate and 3.38 times higher (95% confidence interval, 1.05-10.9) for teeth with no known history of nonsurgical retreatment. Teeth classified as healed in the 1- to 2-year review mostly remained healed at 5- to 9-year review (45/48 teeth); those with uncertain healing had varied outcomes at long-term review. CONCLUSIONS: EMS results in high long-term healed (78.3%, 72/92 teeth) and survival (95.2%) rates. Root-end filling material and nonsurgical retreatment before EMS may influence the long-term outcome.

Incidence of Pulpal Complications after Diagnosis of Vital Cracked Teeth.

INTRODUCTION: This retrospective cohort study aimed to observe the incidence of pulpitis and necrosis in teeth with cracks that were not endodontically treated. METHODS: One hundred eighty-four patients with 199 cracked teeth that were diagnosed with reversible pulpitis and were treated from January 2010 to December 2013 at National Dental Centre, Singapore, were recruited. Cracked teeth were identified by inspection, transillumination, and positive bite tests. A diagnosis of reversible pulpitis was made if the tooth had no history of spontaneous pain, was positive but non-lingering to cold, and there was an absence of any periapical pathosis. Upon diagnosis, orthodontic bands were cemented, and these teeth were referred for crowns. Patients were recalled back at least 3 years after diagnosis, except for those patients whose cracked teeth had undergone endodontic treatment or were extracted. RESULTS: Fifty-eight out of 199 (29.1%) teeth had pulpal complications. Thirty-eight of 58 (65.5%) were diagnosed as irreversible pulpitis after approximately 1.2 years (437 days), and 20 of 58 (34.5%) were diagnosed with necrotic pulp after approximately 2 years (755.5 days). The absence of a full-coverage crown increased the risks of pulp complications (odds ratio = 8.74, P = .000), and males had an increased incidence of pulp complications compared with females (odds ratio = 1.96, P = .056). CONCLUSIONS: Seventy-one percent (141/199) of cracked teeth with reversible pulpitis remained healthy after 3 years. It is essential to brace the cracked tooth to minimize cusp flexion and provide full coverage of the crack from the oral environment. When treated early, these teeth may still reasonably survive for at least 3 years.

Decision Making for Retention of Endodontically Treated Posterior Cracked Teeth: A 5-year Follow-up Study.

INTRODUCTION: The study aimed to investigate the 5-year survival of root-filled posterior cracked teeth and its related factors. METHODS: Two hundred patients who had root canal-treated posterior cracked teeth at the National Dental Centre were recalled for a 5-year review. Eighty-four patients who met the inclusion criteria were included in this study. The cases were managed following the treatment protocol for cracked teeth at the center. The data for analyses were obtained from the patients' clinical records. Statistical analyses were performed using SPSS 21.0 (SPSS Inc, Chicago, IL). The outcome measure was the presence of tooth at the time of the review. RESULTS: At 5 years, 77 teeth "survived" (92%), and 7 teeth (8 %) were extracted. Patient demographics, tooth type and location, existing restoration, number and location of cracks, presence of pretreatment signs and symptoms, and initial pulpal and periapical diagnosis did not significantly affect the survival of the teeth. Univariate analysis showed that teeth with extension of the cracks onto the pulpal floor were more often extracted (odds ratio = 4.5, P = .07). Multivariable analyses found that extension of cracks onto the pulpal floor independently increased the odds of tooth loss by 11-fold (odds ratio = 11, P = .033), with other factors being held constant. The 5-year survival estimate in the absence and presence of crack extension onto the pulpal floor was 99% and 88%, respectively. CONCLUSIONS: Coronal cracks may be predictably treated, whereas radicular cracks increased the odds of the tooth being extracted.

Prognostic factors relating to the outcome of endodontic microsurgery.

INTRODUCTION: The aim of this retrospective study was to evaluate the outcome of endodontic microsurgery and to examine prognostic factors related to healing. METHODS: The clinical records of all patients who had undergone endodontic microsurgery from 1997-2003 at the National Dental Centre of Singapore were examined. Teeth with a recall period of 1-2 years were selected. All surgical procedures, except for flap raising and suturing, were performed under a surgical operating microscope. Root-end cavities prepared with ultrasonic tips were filled with Intermediate Restorative Material (Caulk, Milford, DE) or mineral trioxide aggregate. Teeth were evaluated for clinical signs and symptoms after surgery. Preoperative and postoperative radiographs were evaluated independently by 2 endodontists. RESULTS: Of 243 root-end surgeries performed, 93 were eligible for the study. Outcomes were categorized as healed, healing, or persistent disease; 78.5% of teeth were assessed to be healed or healing, and 21.5% had persistent disease. The percentages of healed and healing teeth for anterior and posterior root-end surgeries were 76.5% and 80.4%, respectively, with no significant difference in the procedures (P = .8). Ordinal logistic regression showed a higher likelihood of healing in females compared with males (P = .001) and maxillary anterior teeth compared with mandibular anterior teeth (P = .03). Preoperative probing depths of ≤3 mm were significantly associated with healing (P = .05). CONCLUSIONS: The use of modern endodontic surgical techniques resulted in 78.5% healed and healing teeth with a recall period of 1-2 years. Prognostic factors affecting successful healing include sex, tooth type, and preoperative probing depths.

The effect of EDTA with and without ultrasonics on removal of the smear layer.

This study evaluated in vitro effectiveness of 17% EDTA with and without ultrasonics on smear layer removal. One hundred and five extracted premolars randomly divided into seven groups were instrumented with different final irrigating protocols: group A (Sal3US), saline for 3 minutes with ultrasonics; groups B (Na3) and C (Na3US), 1% sodium hypochlorite for 3 minutes without and with ultrasonics, respectively; groups D (ED3) and E (ED3US), 17% EDTA for 3 minutes without and with ultrasonics, respectively; and groups F (ED1) and G (ED1US), 17% EDTA for 1 minute without and with ultrasonics, respectively. Specimens were examined under scanning electron microscope and scored for smear layer and debris removal. Statistical analysis showed that groups with EDTA and ultrasonic irrigation, groups E (ED3US) and G (ED1US), had significantly more specimens with complete smear layer and debris removal. There was no significant difference between groups E (ED3US) and G (ED1US). A 1-minute application of combined use of EDTA and ultrasonics is efficient for smear layer and debris removal in the apical region of the root canal.

Effect of EDTA with and without surfactants or ultrasonics on removal of smear layer.

This study compared the in vitro efficacy of Smear Clear (Sybron Endo, CA), a 17% ethylenediaminetetraacetic acid (EDTA) solution with surfactants, to 17% EDTA, with and without the use of ultrasonics, in removal of the smear layer. Seventy-five extracted teeth, randomly distributed into 5 test groups, were prepared by using ProFile rotary instruments (Dentsply Maillefer, Ballaigues, Switzerland) and subjected to different final irrigating regimes; group A, 1% sodium hypochlorite; group B, 17% EDTA; group C, 17% EDTA with ultrasonics; group D, Smear Clear; and group E, Smear Clear with ultrasonics. Samples were examined under the scanning electron microscope and scored for debris and smear layer removal. Statistical analysis showed that groups D and E did not perform significantly better than groups B and C. Group C performed significantly better than group B. Addition of surfactants to EDTA in Smear Clear did not result in better smear layer removal. The use of ultrasonics with 17% EDTA improved smear layer removal.

Stress-strain response in human dentine: rethinking fracture predilection in postcore restored teeth.

In this study, the biomechanical perspective of fracture predilection in post-core restored teeth is investigated using computational, experimental, and fractographic analyses. The computational finite element analysis and the experimental tensile testing are used to evaluate the stress-strain response in structural dentine. The fractographic evaluations are conducted using laser scanning confocal microscopy and scanning electron microscopy to examine the topography of dentine from experimentally fractured specimens, and clinically fractured post-core restored teeth specimens. These experiments aided in correlating the stress-strain response in structural dentine with cracks and catastrophic fractures in post-core restored teeth. It was observed from these experiments that the inner dentine displayed distinctly high strains (deformations), while the outer dentine demonstrated high stresses during tensile loading. This implies that the energy fed into the material as it is extended will be spread throughout the inner dentine, and there is less possibility of local increase in stress at the outer dentine, which can lead to the failure of dentine structure. During post-endodontic restoration with increase in loss of inner dentine, the fracture resistance factor contributed by the inner dentine is compromised, and this in turn predisposes the tooth to catastrophic fracture.