In-vitro effects of novel periodontal scalers with a planar ultrasonic piezoelectric transducer on periodontal biofilm removal, dentine surface roughness, and periodontal ligament fibroblasts adhesion.

OBJECTIVES: To compare ultrasonic scaler prototypes based on a planar piezoelectric transducer with different working frequencies featuring a titanium (Ti-20, Ti-28, and Ti-40) or stainless steel (SS-28) instrument, with a commercially available scaler (com-29) in terms of biofilm removal and reformation, dentine surface roughness and adhesion of periodontal fibroblasts. MATERIALS AND METHODS: A periodontal multi-species biofilm was formed on specimens with dentine slices. Thereafter specimens were instrumented with scalers in a periodontal pocket model or left untreated (control). The remaining biofilms were quantified and allowed to reform on instrumented dentine slices. In addition, fibroblasts were seeded for attachment evaluation after 72 h of incubation. Dentine surface roughness was analyzed before and after instrumentation. RESULTS: All tested instruments reduced the colony-forming unit (cfu) counts by about 3 to 4 log10 and the biofilm quantity (each p < 0.01 vs. control), but with no statistically significant difference between the instrumented groups. After 24-hour biofilm reformation, no differences in cfu counts were observed between any groups, but the biofilm quantity was about 50% in all instrumented groups compared to the control. The attachment of fibroblasts on instrumented dentine was significantly higher than on untreated dentine (p < 0.05), with the exception of Ti-20. The dentine surface roughness was not affected by any instrumentation. CONCLUSIONS: The planar piezoelectric scaler prototypes are able to efficiently remove biofilm without dentine surface alterations, regardless of the operating frequency or instrument material. CLINICAL RELEVANCE: Ultrasonic scalers based on a planar piezoelectric transducer might be an alternative to currently available ultrasonic scalers.

Effect of adrenaline and noradrenaline on biofilm formation and virulence factors of Streptococcus mutans UA159.

OBJECTIVES: To evaluate in vitro the effects of adrenaline and noradrenaline on the biofilm formation on orthodontic brackets, acid production and expression of virulence genes of Streptococcus mutans UA159 (S. mutans). DESIGN: S. mutans UA159 biofilm was formed on orthodontic brackets under exposure to adrenaline (100 µM), noradrenaline (50 µM) or PBS solution (control group) in triptone-yeast extract with 1 % sucrose. After 24 h, biofilm formation was quantified through Colony Forming Units / mL (CFU/mL) and RNA was extracted to perform gene expression analysis through real-time reverse transcriptase-PCR (RT-qPCR). Evaluation of acid production was carried out on planktonic cultures for 6 h. One-way ANOVA followed by Tukey's test was carried to determine statistical difference. The level of significance was set at 5 %. RESULTS: Catecholamines stimulated biofilm formation of S. mutans in orthodontic brackets (p < 0,05) but did not interfere with acid production (pH reduction) or the expression of the tested genes related to biofilm formation (gtfB, gtfC, gbpA, gbpB, gbpC, gbpD and brpA), aciduric (relA) and acidogenic properties (ldh). CONCLUSIONS: The present study was the first to demonstrate that catecholamines can stimulate S. mutans UA159 biofilm formation. These findings can contribute to clarify the role of stress on bacterial metabolism and contribute to the understanding of a possible role on caries development, mainly in orthodontic patients.

In Vitro Effects of Arginine-Containing Toothpastes on Cariogenic Biofilms.

PURPOSE: The effects of arginine as a toothpaste additive were assessed on oral streptococci with and without a known arginine deiminase system (ADS) and cariogenic biofilms. MATERIALS AND METHODS: Suspensions of Streptococcus mutans, S. sobrinus and the ADS-positive (ADS+) S. sanguinis and S. gordonii were cultured with or without 1.5% L-arginine for 24 h. Thereafter, biofilms consisting of the four species were formed on polystyrene surfaces with or without 1.5% L-arginine for up to 10 d. Finally, biofilms that formed on enamel surfaces were exposed to a daily mechanical cleaning with an arginine and sodium monofluorophosphate (SMF+Arg)-containing toothpaste, a sodium monofluorophosphate fluoride (SMF)-containing toothpaste or a negative control for up to 10 weeks. At different incubation times, the pH in the culture media, the citrulline production and the percent of ADS+ bacteria within the biofilms were determined. Microsurface hardness loss was quantified in the experiments using enamel specimens. RESULTS: In the presence of 1.5% arginine, S. sanguinis and S. gordonii showed a high level of production of citrulline after 6 h of incubation, together with an increase in the pH when compared to S. mutans and S. sobrinus. With arginine supplementation, the percentage of ADS+ species was higher at 1, 2 and 4 days and citrulline production was higher at all days of biofilm formation on polystyrene surfaces. After 4 and 10 weeks of treating biofilms on enamel surfaces, the SMF+Arg group had a higher proportion of ADS+ strains than the SMF group; at 4 weeks, the pH was higher in the SMF+Arg group. Loss of enamel hardness was the lowest in the SMF+Arg group and was significantly less in the SMF+Arg group than in the control group after 2, 4 and 10 weeks of treatment. CONCLUSION: Toothbrushing using an arginine-containing toothpaste may protect against dental caries.

In Vitro Effect of Er:YAG Laser on Different Single and Mixed Microorganisms Being Associated with Endodontic Infections.

Objective: The purpose of this in vitro study was to evaluate the antimicrobial effect of activated irrigation with different modes of erbium-doped yttrium aluminum garnet (Er:YAG) laser application on microorganisms related to secondary endodontic infection. Background: Er:YAG laser has been recommended as an adjuvant tool for root canal disinfection during endodontic treatment. Materials and methods: Laser-activated irrigation (LAI) with 300 or 600 µm tips were tested with or without intermittent irrigation with 0.9% sodium chloride (NaCl) solution against different microorganisms (five single strains and dual species (Streptococcus gordonii combined with Actinomyces oris or Fusobacterium nucleatum) in root canals after 3 days of incubation. In a 21-day infection model, LAI was used together with intermittent rinsing with sodium hypochlorite (NaOCl) against the dual-species mixtures; here the incidence of microbial regrowth after up to 7 days was monitored. Results: In the 3-day root infection model, LAI protocols did not show any significant reduction of the microbial load when compared with manual irrigation with saline solution. In the 21-day infection, S. gordonii combined with A. oris were not detectable anymore after applying the LAI protocol with a 600 µm tip (30 mJ/10 pps) up to 7 days after treatment. Conclusions: Application of LAI with a 600 µm tip by using an Er:YAG laser might be advantageous in treatment of endodontic infections.

Effect of articaine on mental nerve anterior portion: histological analysis in rats.

OBJECTIVES: The aim of this study was to evaluate the possible toxic effects of articaine and lidocaine on mental nerve, due to the increasing number of paresthesia cases after nerve blocks. MATERIALS AND METHODS: The drugs were injected in the anterior portion of mental nerve of 24 rats, divided into three groups: G1--4% articaine with 1:100,000 epinephrine; G2--2% lidocaine with 1:100,000 epinephrine and G3--plain 1:100,000 epinephrine solution. These solutions were injected in the right side of the rat's mandible and the left side was used as control (0.9% saline solution). Previously to the injections, the animals were anesthetized with thiopental and, 24 h after the injections, their jaws were removed and submitted to routine histological techniques. A histopathological analysis was performed by optical microscopy. RESULTS: An inflammatory infiltration was found around mental nerve, classified as intense for G3, moderate for G1 and light for both G2 and control groups. No injuries were found in nervous structure, despite the inflammatory reaction observed around it. CONCLUSION: The results suggest that articaine is not toxic to the nervous structure and further studies are necessary to explain the possible relation between articaine injection and paresthesia.

The influence of local anesthetic solutions storageon tissue inflammatory reaction

Objective: This study aimed to analyze the influence of storage conditions of local anesthetic solutions in the inflammatory reaction after injection in rats. Study design: Twenty-four rats received in their oral mucosa the injection of 2% lidocaine with epinephrine1:100.000 solutions (LA) submitted to the following storage conditions during a twelve-month period: G1 - insidethe original packaging, in refrigerator (5±1°C); G2 - inside the original box, under light shelter, at room temperature;G3 - outside the original box at room temperature (exposed to artificial light for 12 hours/day) and G4 - brandnew solution. For the controls tests, 0.9% sodium chloride solution was injected in the opposite side. After 6 and24 hours, three animals of each group were sacrificed and their maxilla along with the soft tissue were removed and submitted to histological analysis (HE). Results: The pH of LA was measured before and after the storage period and no statistically differences were observed between G1 and G4, but both were different from G2 and G3. All the scores of the testing solutions were higher than their respective negative controls, except for G1 at 6 hours. The order of the scores of inflammation after 6 hours was G3>G4>G2=G1. After 24 hours the order was G3>G2>G1>G4. Conclusion: The study showed that the method of storage can influence the pH and the level of inflammatory reaction after the injection of 2% lidocaine with epinephrine 1:100.000 (AU)

The influence of local anesthetic solutions storage on tissue inflammatory reaction.

OBJECTIVE: This study aimed to analyze the influence of storage conditions of local anesthetic solutions in the inflammatory reaction after injection in rats. STUDY DESIGN: Twenty-four rats received in their oral mucosa the injection of 2% lidocaine with epinephrine 1:100.000 solutions (LA) submitted to the following storage conditions during a twelve-month period: G1--inside the original packaging, in refrigerator (5±1°C); G2--inside the original box, under light shelter, at room temperature; G3--outside the original box at room temperature (exposed to artificial light for 12 hours/day) and G4--brand new solution. For the controls tests, 0.9% sodium chloride solution was injected in the opposite side. After 6 and 24 hours, three animals of each group were sacrificed and their maxilla along with the soft tissue were removed and submitted to histological analysis (HE). RESULTS: The pH of LA was measured before and after the storage period and no statistically differences were observed between G1 and G4, but both were different from G2 and G3. All the scores of the testing solutions were higher than their respective negative controls, except for G1 at 6 hours. The order of the scores of inflammation after 6 hours was G3>G4>G2=G1. After 24 hours the order was G3>G2>G1>G4. CONCLUSION: The study showed that the method of storage can influence the pH and the level of inflammatory reaction after the injection of 2% lidocaine with epinephrine 1:100.000.

Anesthetic efficacy of articaine and lidocaine for incisive/mental nerve block.

INTRODUCTION: The incisive/mental nerve block (IMNB) could be an alternative to the inferior alveolar nerve block in the mandibular anterior teeth. The effectiveness of articaine has not been tested in IMNB. METHODS: This prospective randomized double-blind crossover study compared the anesthetic efficacy of 0.6 mL 4% articaine and 2% lidocaine, both with 1:100.000 epinephrine administered as IMNB to 40 volunteers in two sessions. Pulpal anesthesia of lateral incisor through premolars was tested with an electric pulp tester. The injection and postoperative pain were evaluated by using visual analog scales. The onset (time from the end of injection to the absence of pulpal response) and duration of pulpal anesthesia (time recorded before two positive responses to the pulp tester) and the anesthesia success (two consecutive readings of 80 without response and onset0.05). CONCLUSIONS: Articaine promoted higher anesthesia success and longer duration of anesthesia than lidocaine for most of the teeth after IMNB although anesthesia success could be considered clinically appropriated only for premolars. The volume of local anesthetic used in the present study may not be appropriate for procedures lasting longer than 10 minutes.