Single versus multiple visits for endodontic treatment of permanent teeth.

BACKGROUND: Root canal treatment (RoCT), or endodontic treatment, is a common procedure in dentistry. The main indications for RoCT are irreversible pulpitis and necrosis of the dental pulp caused by carious processes, coronal crack or fracture, or dental trauma. Successful RoCT is characterised by an absence of symptoms (i.e. pain) and clinical signs (i.e. swelling and sinus tract) in teeth without radiographic evidence of periodontal involvement (i.e. normal periodontal ligament). The success of RoCT depends on a number of variables related to the preoperative condition of the tooth, as well as the endodontic procedures. RoCT can be carried out with a single-visit approach, which involves root canal system obturation (filling and sealing) directly after instrumentation and irrigation, or with a multiple-visits approach, in which the treatment is completed in two or more sessions and obturation is performed in the last session. This review updates the previous versions published in 2007 and 2016. OBJECTIVES: To evaluate the benefits and harms of completion of root canal treatment (RoCT) in a single visit compared to RoCT over two or more visits, with or without medication, in people aged over 10 years. SEARCH METHODS: We used standard, extensive Cochrane search methods. The latest search date was 25 April 2022. SELECTION CRITERIA: We included randomised controlled trials and quasi-randomised controlled trials in people needing RoCT comparing completion of RoCT in a single visit compared to RoCT over two or more visits.  DATA COLLECTION AND ANALYSIS: We used standard Cochrane methods. Our primary outcomes were 1. tooth extraction and 2. radiological failure after at least one year (i.e. periapical radiolucency). Our secondary outcomes were 3. postoperative and postobturation pain; 4. swelling or flare-up; 5. analgesic use and 6. presence of sinus track or fistula after at least one month. We used GRADE to assess certainty of evidence for each outcome. We excluded five studies that were included in the previous version of the review because they did not meet the current standard of care (i.e. rubber dam isolation and irrigation with sodium hypochlorite). MAIN RESULTS: We included 47 studies with 5805 participants and 5693 teeth analysed. We judged 10 studies at low risk of bias, 17 at high risk of bias and 20 at unclear risk of bias. Only two studies reported data on tooth extraction. We found no evidence of a difference between treatment in one visit or treatment over multiple visits, but we had very low certainty about the findings (risk ratio (RR) 0.46, 95% confidence interval (CI) 0.09 to 2.50; I2 = 0%; 2 studies, 402 teeth). We found no evidence of a difference between single-visit and multiple-visit treatment in terms of radiological failure (RR 0.93, 95% CI 0.81 to 1.07; I2 = 0%; 13 studies, 1505 teeth; moderate-certainty evidence). We found evidence of a higher proportion of participants reporting pain within one week in single-visit groups compared to multiple visit groups (RR 1.55, 95% CI 1.14 to 2.09; I2 = 18%; 5 studies, 638 teeth; moderate-certainty evidence).  We found no evidence of a difference in the proportion of participants reporting pain until 72 hours postobturation (RR 0.97, 95% CI 0.81 to 1.16; I2 = 70%; 12 studies, 1329 teeth; low-certainty evidence), pain intensity until 72 hours postobturation (mean difference (MD) 0.26, 95% CI -4.76 to 5.29; I2 = 98%; 12 studies, 1258 teeth; low-certainty evidence) or pain at one week postobturation (RR 1.05, 95% CI 0.67 to 1.67; I2 = 61%; 9 studies, 1139 teeth; very low-certainty evidence). We found no evidence of a difference in swelling or flare-up incidence (RR 0.56 95% CI 0.16 to 1.92; I2 = 0%; 6 studies; 605 teeth; very low-certainty evidence), analgesic use (RR 1.25 95% CI 0.75 to 2.09; I2 = 36%; 6 studies, 540 teeth; very low-certainty evidence) or sinus tract or fistula presence (RR 1.00, 95% CI 0.24 to 4.28; I2 = 0%; 5 studies, 650 teeth; very low-certainty evidence). Subgroup analysis found no differences between single-visit and multiple-visit RoCT for considered outcomes other than proportion of participants reporting post-treatment pain within one week, which was higher in the single-visit groups for vital teeth (RR 2.16, 95% CI 1.39 to 3.36; I2 = 0%; 2 studies, 316 teeth), and when instrumentation was mechanical (RR 1.80, 95% CI 1.10 to 2.92; I2 = 56%; 2 studies, 278 teeth). AUTHORS' CONCLUSIONS: As in the previous two versions of the review, there is currently no evidence to suggest that one treatment regimen (single-visit or multiple-visit RoCT) is more effective than the other. Neither regimen can prevent pain and other complications in the 12-month postoperative period. There was moderate-certainty evidence of higher proportion of participants reporting pain within one week in single-visit groups compared to multiple-visit groups. In contrast to the results of the last version of the review, there was no difference in analgesic use.

Immediate Autotransplantation of Molars with Closed Apex.

AIM: The aim of this study was to evaluate clinical features that might be related to success rates of autotransplantation of molars with complete root formation. MATERIALS AND METHODS: A group of 60 patients with completely formed third molars autotransplanted to a different molar socket was followed for a medium period of 5 years and 5 months. Extreme care was used in order to preserve the vitality of the periodontal ligament cells. The same technique was applied for all teeth despite different anatomies. Descriptive statistics was performed. The association of the various factors with failures was assessed by using the Fisher's exact test and a p-value of 0.05 was considered as significance threshold. RESULTS: Autotransplantation was found to be a reliable method to replace extracted molar teeth with closed apices. The two major factors that positively influenced the outcomes were fixation with splint and a periodontal probing pocket depth less than 4 mm after the initial healing period. The technique resulted in a suitable well-conserved socket and donor tooth, after the extraction. CONCLUSION: An accurate case evaluation was critically important in order to identify the risks prior to surgery and to select the right patients for this procedure. Autotransplantation of third molar teeth is a feasible approach to replace compromised mature molars. Proper stabilization of the transplanted tooth is strategical for the success of this procedure. A conservative approach to unerupted wisdom teeth is also recommended. CLINICAL SIGNIFICANCE: Dental implants and fixed prostheses have been utilized to replace missing teeth, and orthodontic space closure can be sometimes an effective treatment option. Tooth autotransplantation can be a reliable and less invasive clinical alternative when an appropriate donor site is available.

Prognostic Factors and Primary Healing on Root Perforation Repaired with MTA: A 14-year Longitudinal Study.

INTRODUCTION: Few data are available on the long-term efficacy of mineral trioxide aggregate (MTA) in treating root canal perforations. This prospective cohort study builds on a previously reported trial to determine the outcome for teeth with root perforations treated with orthograde MTA after longer follow-up and identify potential prognostic factors. METHODS: A prospective cohort study was performed, enrolling (1999-2009) patients with a single dental perforation treated with MTA. Preoperative, intraoperative, and postoperative information was evaluated, and the outcomes were dichotomized as healed or nonhealing. Patients were followed up yearly until 2018 for a maximum of 17 years after treatment, with controls carried out until 14 years. Clinical and radiographic outcomes were evaluated using standardized follow-up protocols. RESULTS: Of the 124 entrolled patients (median age = 36.5 years, 53.2% male), 115 were healed at the first (n = 110, 89%) or second (n = 5, 4%) annual posttreatment checkup, while 9 subjects (7%, 4 females, 18-65 years old) did not heal. Characteristics significantly associated with nonhealing were gender, positive probing, size, and perforation site. Perforations recurred in 48 teeth during the follow-up with the estimated probability of reversal at 5, 10, and 14 years of 6% (95% confidence interval [CI], 2%-10%), 30% (95% CI, 20%-38%), and 62% (95% CI, 46%-73%), respectively. Positive probing had a higher reversal risk (hazard ratio = 3.3, P ≤ .001), and perforations >3 mm were more likely to have a reversal (hazard ratio = 4.1, P < .001). CONCLUSIONS: The risk of reversal for healed MTA-treated root canal perforations, initially relatively low, vastly increases over time.

Cone-beam computed tomography accuracy in pulp chamber size evaluation: An ex vivo study.

This study aimed to assess ex vivo the accuracy of cone-beam computed tomography (CBCT), as compared to operative microscope, for evaluating pulp chamber size. A total of forty teeth were extracted for periodontal reasons and a horizontal section was done at the most apical level of the cement-enamel junction. The pulp chamber was photographed using a digital camera connected to an optical microscope. Then, the tooth was scanned with CBCT and the horizontal slide matching the anatomical section of pulp chamber was digitally stored. The pulp chamber section area was measured through image analysis software. The two methods provided similar results, either for monoradicular (P = 0.14) or multiradicular teeth (P = 0.93). Correlation was statistically significant (P < 0.0001), being the coefficient r = 0.89 and 0.94 for monoradicular and multiradicular teeth, respectively. Conclusively, CBCT is suitable for pulp chamber morphology evaluation. However, it has limitations in detecting the anatomical variability of small branches in root canal system.

An in vitro evaluation of the degree of pulp tissue dissolution through different root canal irrigation protocols.

AIM: The aim of this study is to evaluate in vitro, using artificial lateral canals, the rate of dissolution of the pulp tissue through different protocols of canal irrigation. MATERIALS AND METHODS: One hundred artificial canals provided with lateral canals have been used. Each lateral canal was filled with pulp tissue and calibrated to 0.002 mg. All canals were irrigated using five different protocols. Five groups have been used for the experiment: Group A, distilled water (control); Group B, preheated NaOCl; Group C, NaOCl heated inside the canal; Group D, NaOCl ultrasonically activated; and Group E, NaOCl heated inside the canal with ultrasonic activation. All samples were weighed through professional microbalance in three different phases: before insertion of the pulp tissue into the lateral canal, after insertion of the pulp tissue and, finally, after different protocols of irrigation. A statistical analysis with Kruskal-Wallis test and Mann-Whitney test was performed. RESULTS: The partial dissolution of the pulp tissue inside the artificial lateral canal occurs only using the protocol with NaOCl heated inside the canal with ultrasonic activation. Other irrigation protocols are not able to dissolve the pulp tissue. DISCUSSION AND CONCLUSIONS: The main objective of endodontic therapy is the removal of damaged tissues and bacteria. Modern literature highlights that it is impossible to remove all the pulp tissues and bacteria from the whole endodontic space. Hence, to achieve excellence and get positive results in the short and long term, it is necessary to use techniques and technologies that may increase the degree of root canal detersion.

New adhesives and bonding techniques. Why and when?

Nowadays, adhesive dentistry is a fundamental part of daily clinical work. The evolution of adhesive materials and techniques has been based on the need for simplicity in the step-by-step procedures to obtain long-lasting direct and indirect restorations. For this reason, recently introduced universal multimode adhesives represent a simple option for creating a hybrid layer, with or without the use of phosphoric acid application. However, it is important to understand the limitations of this latest generation of adhesive systems as well as how to use them on coronal and radicular dentin. Based on the findings in the literature, universal multimode adhesives have shown promising results, even if the problem of hybrid layer degradation due to the hydrolytic activity of matrix metalloproteinases (MMPs) still exists. Studies are therefore required to help us understand how to reduce this degradation.

Single versus multiple visits for endodontic treatment of permanent teeth.

BACKGROUND: Root canal treatment (RoCT), or endodontic treatment, is a common procedure in dentistry. The main indications for RoCT are irreversible pulpitis and necrosis of the dental pulp caused by carious processes, tooth cracks or chips, or dental trauma. Successful RoCT is characterised by an absence of symptoms (i.e. pain) and clinical signs (i.e. swelling and sinus tract) in teeth without radiographic evidence of periodontal involvement (i.e. normal periodontal ligament). The success of RoCT depends on a number of variables related to the preoperative condition of the tooth, as well as the endodontic procedures. This review updates the previous version published in 2007. OBJECTIVES: To determine whether completion of root canal treatment (RoCT) in a single visit or over two or more visits, with or without medication, makes any difference in term of effectiveness or complications. SEARCH METHODS: We searched the following electronic databases: Cochrane Oral Health's Trials Register (to 14 June 2016), Cochrane Central Register of Controlled Trials (CENTRAL) (the Cochrane Library, 2016, Issue 5), MEDLINE Ovid (1946 to 14 June 2016), and Embase Ovid (1980 to 14 June 2016). We searched ClinicalTrials.gov and the World Health Organization International Clinical Trials Registry Platform for ongoing trials to 14 June 2016. We did not place any restrictions on the language or date of publication when searching the electronic databases. SELECTION CRITERIA: We included randomised controlled trials (RCTs) and quasi-RCTs of people needing RoCT. We excluded surgical endodontic treatment. The outcomes of interest were tooth extraction for endodontic problems; radiological failure after at least one year, i.e. periapical radiolucency; postoperative pain; swelling or flare-up; painkiller use; sinus track or fistula formation; and complications (composite outcome including any adverse event). DATA COLLECTION AND ANALYSIS: We collected data using a specially designed extraction form. We contacted trial authors for further details where these were unclear. We assessed the risk of bias in the studies using the Cochrane tool and we assessed the quality of the body of evidence using GRADE criteria. When valid and relevant data were collected, we undertook a meta-analysis of the data using the random-effects model. For dichotomous outcomes, we calculated risk ratios (RRs) and 95% confidence intervals (CIs). For continuous data, we calculated mean differences (MDs) and 95% CIs. We examined potential sources of heterogeneity. We conducted subgroup analyses for necrotic and vital teeth. MAIN RESULTS: We included 25 RCTs in the review, with a total of 3780 participants, of whom we analysed 3751. We judged three studies to be at low risk of bias, 14 at high risk, and eight as unclear.Only one study reported data on tooth extraction due to endodontic problems. This study found no difference between treatment in one visit or treatment over multiple visits (1/117 single-visit participants lost a tooth versus 2/103 multiple-visit participants; odds ratio (OR) 0.44, 95% confidence interval (CI) 0.04 to 4.78; very low-quality evidence).We found no evidence of a difference between single-visit and multiple-visit treatment in terms of radiological failure (risk ratio (RR) 0.91, 95% CI 0.68 to 1.21; 1493 participants, 11 studies, I2 = 18%; low-quality evidence); immediate postoperative pain (dichotomous outcome) (RR 0.99, 95% CI 0.84 to 1.17; 1560 participants, 9 studies, I2 = 33%; moderate-quality evidence); swelling or flare-up incidence (RR 1.36, 95% CI 0.66 to 2.81; 281 participants, 4 studies, I2 = 0%; low-quality evidence); sinus tract or fistula formation (RR 0.98, 95% CI 0.15 to 6.48; 345 participants, 2 studies, I2 = 0%; low-quality evidence); or complications (RR 0.92, 95% CI 0.77 to 1.11; 1686 participants, 10 studies, I2 = 18%; moderate-quality evidence).The studies suggested people undergoing RoCT in a single visit may be more likely to experience pain in the first week than those whose RoCT was over multiple visits (RR 1.50, 95% CI 0.99 to 2.28; 1383 participants, 8 studies, I2 = 54%), though the quality of the evidence for this finding is low.Moderate-quality evidence showed people undergoing RoCT in a single visit were more likely to use painkillers than those receiving treatment over multiple visits (RR 2.35, 95% CI 1.60 to 3.45; 648 participants, 4 studies, I2 = 0%). AUTHORS' CONCLUSIONS: There is no evidence to suggest that one treatment regimen (single-visit or multiple-visit root canal treatment) is better than the other. Neither can prevent all short- and long-term complications. On the basis of the available evidence, it seems likely that the benefit of a single-visit treatment, in terms of time and convenience, for both patient and dentist, has the cost of a higher frequency of late postoperative pain (and as a consequence, painkiller use).

Patient and Clinical Characteristics Associated with Primary Healing of Iatrogenic Perforations after Root Canal Treatment: Results of a Long-term Italian Study.

INTRODUCTION: There are few data on the long-term efficacy of mineral trioxide aggregate (MTA) in treating root canal perforations. We investigated the extent of primary healing after perforation repair with MTA and non-healing as a result of repair. We also investigated patient/clinical characteristics affecting treatment outcomes and long-term prognosis. METHODS: This was a prospective cohort study that enrolled consecutive patients with a single dental perforation treated with MTA (January 1999-June 2009). Patients were followed up until December 2012 for a maximum of 13 years after treatment, with analyses carried out at 8 years. RESULTS: Of the 110 patients (median age, 36 years; 54.5% male) eligible for inclusion, 101 were judged to have started to heal at the first (n = 98, 89%) or second (n = 3, 3%) annual post-treatment checkup, and 9 (8%, 4 women and 5 men, aged between 18 and 65 years) did not show any sign of healing. Patients >50 years had a higher percentage of non-healing perforations compared with those ≤ 50 years (12% versus 7%). The percentages of perforations at post-treatment analysis that failed to heal were 13% (intermediate/middle), 4% (coronal), and 0% (apical). The percentages of non-healing perforations according to size were 16% for >3 mm, 6% for 2-3 mm, and 0% for smaller perforations. Characteristics associated with probability of progressing after initial healing were gender, positive probing, size, and site of perforation. CONCLUSIONS: Our results show that having obtained primary healing with MTA, the likelihood of progressing is very low. They provide good evidence of the combined effectiveness of experienced operators and use of state-of-the-art materials.

The influence of antibacterial toothpastes on in vitro Streptococcus mutans biofilm formation: a continuous culture study.

PURPOSE: To evaluate the in vitro effect of five toothpastes containing antimicrobial compounds including fluoride, triclosan or hydroxyapatite nano-particles on Streptococcus mutans (S. mutans) biofilm formation. Fluoride uptake by enamel after bacterial challenge was also evaluated. METHODS: Human enamel disks (n= 192) were randomly divided into six groups and brushed with five different toothpastes while the control group was brushed with distilled water. Each group was incubated for 24 and 72 hours with a S. mutans biofilm growing on a modified drip-flow reactor (MDFR). Biofilm formation was determined using a viable biomass assay based on a tetrazolium salt (MTT) and evaluated morphologically with confocal laser-scanning microscopy (CLSM) and scanning electron-microscopy (SEM). Fluoride uptake was evaluated using the enamel biopsy technique. Biofilm formation was also evaluated using 120 disks randomly divided into the same six groups. The number of viable bacteria was determined through plate count on Mitis Salivarius Bacitracin agar (MSB agar). RESULTS: Data from plate count showed the same overall trend of MTT assay. The latter showed that after 24 hours the effect of the tested toothpastes was significantly higher in reducing biofilm formation than after 72 hours. The toothpaste containing a high concentration of amine fluoride (AmF) had the highest performance in reducing biofilm formation. Fluoride uptake of enamel showed a positive trend related to the fluoride concentration in both incubation times.

Hydrophilicity of dentin bonding systems influences in vitro Streptococcus mutans biofilm formation.

OBJECTIVE: To evaluate in vitro Streptococcus mutans (S. mutans) biofilm formation on the surface of five light-curing experimental dental bonding systems (DBS) with increasing hydrophilicity. The null hypothesis tested was that resin chemical composition and hydrophilicity does not affect S. mutans biofilm formation. METHODS: Five light-curing versions of experimental resin blends with increasing hydrophilicity were investigated (R1, R2, R3, R4 and R5). R1 and R2 contained ethoxylated BisGMA/TEGDMA or BisGMA/TEGDMA, respectively, and were very hydrophobic, were representative of pit-and-fissure bonding agents. R3 was representative of a typical two-step etch-and-rinse adhesive, while R4 and R5 were very hydrophilic resins analogous to self-etching adhesives. Twenty-eight disks were prepared for each resin blend. After a 24h-incubation at 37°C, a multilayer monospecific biofilm of S. mutans was obtained on the surface of each disk. The adherent biomass was determined using the MTT assay and evaluated morphologically with confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). RESULTS: R2 and R3 surfaces showed the highest biofilm formation while R1 and R4 showed a similar intermediate biofilm formation. R5 was more hydrophilic and acidic and was significantly less colonized than all the other resins. A significant quadratic relationship between biofilm formation and hydrophilicity of the resin blends was found. CLSM and SEM evaluation confirmed MTT assay results. CONCLUSIONS: The null hypothesis was rejected since S. mutans biofilm formation was influenced by hydrophilicity, surface acidity and chemical composition of the experimental resins. Further studies using a bioreactor are needed to confirm the results and clarify the role of the single factors.

Marginal quality of posterior microhybrid resin composite restorations applied using two polymerisation protocols: 5-year randomised split mouth trial.

OBJECTIVES: This randomised, split-mouth clinical study evaluated the marginal quality of direct Class I and Class II restorations made of microhybrid composite and applied using two polymerisation protocols, using two margin evaluation criteria. METHODS: A total of 50 patients (mean age: 33 years) received 100 direct Class I or Class II restorations in premolars or molars. Three calibrated operators made the restorations. After conditioning the tooth with 2-step etch-and-rinse adhesive, restorations were made incrementally using microhybrid composite (Tetric EvoCeram). Each layer was polymerised using a polymerisation device operated either at regular mode (600-650 mW/cm(2) for 20s) (RM) or high-power (1200-1300 mW/cm(2) for 10s) mode (HPM). Two independent calibrated operators evaluated the restorations 1 week after restoration placement (baseline), at 6 months and thereafter annually up to 5 years using modified USPHS and SQUACE criteria. Data were analyzed using Mann-Whitney U-test (α=0.05). RESULTS: Alfa scores (USPHS) for marginal adaptation (86% and 88% for RM and HPM, respectively) and marginal discoloration (88% and 88%, for RM and HPM, respectively) did not show significant differences between the two-polymerisation protocols (p>0.05). Alfa scores (SQUACE) for marginal adaptation (88% and 88% for RM and HPM, respectively) and marginal discoloration (94% and 94%, for RM and HPM, respectively) were also not significantly different at 5th year (p>0.05). CONCLUSION: Regular and high-power polymerisation protocols had no influence on the marginal quality of the microhybrid composite tested up to 5 years. Both modified USPHS and SQUACE criteria confirmed that regardless of the polymerisation mode, marginal quality of the restorations deteriorated compared to baseline.

Influence of MDPB-containing primer on Streptococcus mutans biofilm formation in simulated Class I restorations.

PURPOSE: To evaluate the activity of a methacryloyloxydodecylpyridinium bromide (MDPB)-containing self-etching primer (Clearfil Protect Bond) against Streptococcus mutans and its ability to reduce biofilm formation on standardized experimental Class I restorations in vitro. MATERIALS AND METHODS: Forty experimental Class I round restorations were prepared on enamel-dentin slabs using different adhesive strategies: group 1 = MDPB-containing adhesive system (Clearfil Protect Bond); group 2 = MDPB-free self-etching adhesive system (Clearfil SE Bond); group 3: MDPB-containing self-etching primer in combination with a fluoride-free bonding agent; group 4: MDPB-free self-etching primer in combination with a fluoride-containing bonding agent; group 5: a three-step etch-and-rinse adhesive system (Adper Scotchbond Multi Purpose). A Streptococcus mutans biofilm was grown for 48 h on the restoration surfaces and subsequently evaluated using scanning electron microscopy on three different areas: enamel, composite, and interface surfaces. Statistical analysis was performed by multiple ANOVA after data transformation. RESULTS: Specimens in groups 2, 4 and 5 showed greater biofilm formation than those in groups 1 and 3 (p < 0.001) on all investigated substrates (enamel, composite, and interface areas). CONCLUSIONS: Specimens prepared with an MDPB-containing primer exhibited significant decreases in biofilm formation on Class I restorations in vitro. Further in vitro and in vivo studies are required to clarify the role of quaternary ammonium compounds in reducing bacterial biofilm formation on restoration surfaces.

Biofilm formation on composite resins for dental restorations: an in situ study on the effect of chlorhexidine mouthrinses.

PURPOSE: Biofilm formation on the surface of dental restorative materials by oral bacteria is considered an important step in the development of secondary caries. The aim of this study was to evaluate the in situ effect of a chlorhexidine (CHX)-containing mouthrinse on the biofilm formation occurring on the surface of human enamel and of two resin-based commercially available materials: a silorane-based material (Filtek Silorane®) and a methacrylate-based material (Filtek Supreme XT®). METHODS: 53 disks were obtained for each of the two composites and 37 disks for enamel. The surface was characterized by determining the surface roughness and the surface free energy of 5 samples for each of the three materials tested, then the remaining samples were mounted on splints worn by 16 volunteers. The participants were randomly divided into two groups: an experimental group that used 0.12% CHX-based mouthrinse and a control group that used a placebo mouthrinse. Biofilm formation on the different surfaces after a 24 h period was assessed using MTT assay. RESULTS: The two composites in the group treated with the placebo mouthrinse showed a similar biofilm formation, which was significantly higher than that occurring on enamel surfaces. The CHX-based mouthrinse significantly reduced biofilm formation on the surfaces of the two resin-based materials when compared with the placebo mouthrinse. The reduction was particularly relevant on the Filtek Silorane surfaces. CONCLUSIONS: The new silorane-based material seems to interact with CHX in a promising way from the point of view of biofilm formation control.

Removal of surgical smear layer.

INTRODUCTION: During apicoectomy and retrograde cavity preparation, a smear layer, which contains microorganisms and necrotic pulpal tissues, is formed on the dentinal surfaces cut by the instruments. Bacteria can survive and proliferate inside or below the smear layer. The purpose of this study was to evaluate in vitro two different procedures for the removal of the smear layer in retrocavities prepared with ultrasonic retrotips. METHODS: Twenty-eight single-rooted teeth were cleaned, shaped, and obturated with gutta-percha and sealer. The apical 3 mm of each root were cut with a carbide bur, and retrograde cavities were prepared with ProUltra ultrasonic retrotips (Maillefer Dentsply, Baillagues, Switzerland) at a depth of 3 mm. Teeth in group A were treated with a gel of 35% orthophosphoric acid for 15 seconds, and teeth in group B were treated with a gel of 24% EDTA at a neutral pH for 2 minutes. The samples were prepared for scanning electron microscopic observation and scored for the presence of the smear layer on the retrocavity walls. RESULTS: Eighty percent of the teeth in group A showed an optimal degree of cleanliness of the walls, with dentinal tubules completely open. The majority of analyzed samples coming from group B showed dentinal tubules covered with the smear layer. CONCLUSIONS: The analysis of the samples showed that orthophosphoric acid is more effective than EDTA in removing surgical smear layer even with less time of action.

Degree of conversion of dual-cure resins light-cured through glass-fiber posts.

PURPOSE: To evaluate the degree of conversion (DC) of dual-curing materials used to lute glass-fiber posts in a simulated root canal polymerized by two different modalities. METHODS: Artificial root canals were used to simulate a clinical condition to lute 45 posts by three different dual curing luting cements (Calibra, Multilink Automix and Variolink II). Two light cure modalities were chosen for each luting cement: standard (S group) 400 mW/cm2 for 120 seconds and high-power (H group) 1200 mW/cm2 for 40 seconds. Raman spectra were collected at different positions in the post surface (1, 3, 5 and 7 mm from the coronal-most portion of the post covered in cement) and the percentage degree of conversion was computed. The data were analyzed using ANOVA and post-hoc Student-Neuman-Keuls t-test (P = 0.05). RESULTS: The DC of the tested luting composites decreased progressively while increasing the distance from the light tip. Regardless of the polymerization modality (H or S) applied. Conversely, the curing modality significantly influenced the DC of the tested materials, evidencing different responses to the same energy density: Calibra seemed to be less dependent on light-curing than the other tested materials, showing a constant behavior. Multilink Automix reached the highest DCs in the S group compared to the H mode. Variolink II showed an interesting drawback in DC at 7 mm when cured in the H model. Dual-cure materials show adequate monomer conversion but when the distance from the curing light increased, a variable, but significant lowering in conversion rate was observed. In addition, the time and power of curing appeared to be material-dependent and should be calibrated individually.

Adhesive restoration of endodontically treated premolars: influence of posts on cuspal deflection.

PURPOSE: To determine, by means of a non-destructive experimental procedure, the effectiveness of adhesive restorations in reducing the cuspal deflection of endodontically treated premolars, with or without root canal fiber posts. MATERIALS AND METHODS: The cuspal deflection of ten sound, intact maxillary premolars was evaluated. A loading device induced deformation by axial force (ranging from 98 to 294 N) applied on the occlusal surface of teeth while laser sensors registered the amount of deflection. Once tested, teeth were endodontically treated and the marginal ridges were removed. The teeth were randomly divided into two groups and restored with: group 1) dual curing adhesive, flowable composite, and microhybrid composite; group 2) the same materials associated with root canal glass fiber post and composite cement. The cuspal deflection test was repeated with the same protocol after restorative procedures, allowing a direct comparison of the same samples. Statistical analysis was performed using ANOVA at a significance level of 0.05. RESULTS: Different average cuspal deflection was detected in the two groups: composite resin with post insertion resulted in lower deformation compared with composite alone. Mean deflection ranged from 3.43 to 12.17 µm in intact teeth, from 14.42 to 26.93 µm in group 1, and from 15.35 to 20.39 µm in group 2. ANOVA found significant differences (p = 0.02). CONCLUSION: Bonded composite restorations with fiber posts may be more effective than composite alone in reducing the cuspal deflection in endodontically treated premolars in which the marginal ridges have been lost.

Degree of conversion of three composite materials employed in the adhesive cementation of indirect restorations: a micro-Raman analysis.

OBJECTIVES: Adhesive luting of indirect restorations can be carried out employing dual- or light-curing materials. This in vitro study evaluated the degree of conversion (DC) of the materials employed in this procedure, seeking how the combination of time and power of curing applied during polymerisation, as well as the temperature of the light-curing composite, influenced the DC. MATERIALS AND METHODS: One hundred and eighty onlays of different thicknesses (2 mm, 3 mm, 4 mm) were luted with three different composites: two dual-curing cements (Variolink II and Calibra) and a light-curing composite (Venus). The same halogen lamp was used with three different modalities selected to provide a constant quantity of energy. The time/power combinations tested were 400 mW/cm(2) for 120 s, 800 mW/cm(2) for 60s and 1200 mW/cm(2) for 40 s. The light-curing composite was employed at room temperature and after preheating at 54 degrees C. Each sample was examined in three positions using the Micro-Raman Dilor HR LabRam spectrometer to evaluate the polymer conversion degree. The data were analysed using analysis of variance and the Student-Newman-Keuls test (p=0.05). RESULTS: The dual-curing materials showed average conversion percentages close to 64%, although onlays thickness clearly influence the degree of conversion, the light-curing composite showed satisfactory results only when onlays thickness was thin, however preheating significantly improved the performance of the light-curing composite under onlays of great thickness. CONCLUSIONS: Optimal luting of indirect restorations is clearly dependent from light source power, irradiation time and dual-cure luting cement or light-curing composite chosen. It should be calibrated for each material to acquire high DCs. Preheating of light-curing only composites allows for the materials to reach optimal conversion degrees.

Cytotoxicity of epiphany SE endodontic sealer: a comparative in vitro study.

BACKGROUND: The Epiphany endodontic obturation system, which was developed for use with all current root canal-filling techniques by substituting for gutta-percha and sealer, has been recently modified by eliminating the priming step and introducing a new self-etch, dual-cure, resin-based sealer; Epiphany SE. As with all new endodontic compounds, this novel material should undergo preliminary testing for biocompatibility. The aim of the present study was to investigate the in vitro cytotoxicity of Epiphany SE and to compare it with the original Epiphany sealer and with a commonly used endodontic sealer (Pulp Canal Sealer). MATERIAL/METHODS: Mouse 3T3 fibroblasts were seeded and cultured, and extracts of each of the cemented sealers were added. After a 24-hour incubation, cell viability was evaluated by neutral red uptake assay, which is an indicator of membrane permeability. The greater the cell mortality (measured as a percentage), the greater the toxicity of the sealer. RESULTS: Results showed that all 3 of the tested sealers exhibited cytotoxic effects compared to the control group (P<0.05), but no statistically significant differences (P>0.05) were noted among the sealers. CONCLUSIONS: Our results showed satisfactory biocompatibility of the new Epiphany SE sealer, which showed similar biocompatibility to the original Epiphany sealer and to the traditional zinc oxide eugenol-based sealer.

The influence of light-curing time on the bacterial colonization of resin composite surfaces.

OBJECTIVES: Bacterial colonization of composite surfaces represents the main factor in the etiology of secondary caries around adhesive restorations. The authors' aim was to evaluate the influence of light-curing time on mutans streptococci colonization (MS) of a resin composite material. METHODS: Specimens obtained from a dental resin composite were divided into 12 groups and light-cured with the same light source respectively for 10, 20, 30, 40, 60 or 80 s using two different curing-power levels: 400 and 800 mW/cm2. A wild strain of MS was isolated and a 24-h-monospecific biofilm, adherent to the surfaces of the samples, was obtained. A colorimetric technique (MTT assay), based on the reduction of a yellow tetrazolium salt to a purple formazan, was used to evaluate the biomass adherent to the specimen surfaces. ANOVA and Scheffé's tests were used to statistically analyze the results. RESULTS: Two-way ANOVA demonstrated there was no interaction between curing-time factor and curing-power factor (p=0.970); one-way ANOVA was used to analyze separately the data obtained from each curing-power level. Both levels showed highly significant differences (p<0.0001) among the different curing time groups. The non-parametric test for trend showed in both levels the existence of a highly significant trend (p<0.0001) for bacterial colonization reduction as curing time increases. SIGNIFICANCE: A reduced curing time seems to be responsible for increased in vitro colonization of composite surfaces by MS; this phenomenon is likely to be related to the presence of unpolymerized monomers on the material surface.