Carlos Estrela

Detection of periodontal bone loss using cone beam CT and intraoral radiography

OBJECTIVEnThe aim of this study was to compare periapical radiographs with cone beam CT (CBCT) imaging in detecting and localizing alveolar bone loss by comparing linear measurements of the height, depth and width of the defects and identifying combined bone defects in tomographic images.nnnMETHODSnThe images were selected from a secondary database containing images of patients referred for periodontal evaluation. The sample consisted of 51 sites showing both horizontal and vertical bone loss, assessed by 3 trained examiners.nnnRESULTSnThe results showed that there were no statistically significant differences between the imaging methods in terms of identification of the pattern of bone loss. However, there were differences between the two methods when the distance between the cemento-enamel junction (CEJ) and the alveolar crest (AC) was measured. When the distance between the CEJ and the deepest point and width of the defect were measured, the methods showed no statistically significant difference. In this study, 30.8% of the 39 teeth evaluated had combined bone defects.nnnCONCLUSIONSnThe two methods differ when detecting the height of the alveolar bone crest but present similar views of the depth and width of bone defects. CBCT was the only method that allowed for an analysis of the buccal and lingual/palatal surfaces and an improved visualization of the morphology of the defect.

Two Methods to Evaluate the Antimicrobial Action of Calcium Hydroxide Paste

The objective of this study was to analyze two methods for determining the antimicrobial effectiveness of (i) calcium hydroxide plus saline, (ii) calcium hydroxide plus polyethylene glycol, and (iii) calcium hydroxide plus camphorated paramonochlorophenol. Four microorganisms (Staphylococcus aureus (ATCC 6538), Enterococcus faecalis (ATCC 29212), Pseudomonas aeruginosa (ATCC 27853), and Bacillus subtilis (ATCC 6633)), one yeast (Candida albicans (ICB/USP-562)), and one mixture of these organisms were used. The strains were inoculated in Brain Heart Infusion (BHI) and incubated at 37 degrees C for 24 h. Two methods, the direct exposure test and the agar diffusion test were used to evaluate antimicrobial effects. For the direct exposure test (DET) 288 paper points were contaminated with the standard microbial suspensions and exposed to the intracanal dressings for 1, 24, 48, and 72 h. The points were immersed in Letheen Broth, followed by incubation at 37 degrees C for 48 h. An inoculum of 0.1 ml obtained from Letheen Broth was then transferred to 7 ml of BHI under identical incubation conditions, and microbial growth was evaluated. Pastes showed activity between 1 and 72 h, depending on the microorganism/mixture tested. For the agar diffusion test 36 Petri plates with 20 ml of BHI agar were inoculated with 0.1 ml of the same microbial suspension used for the DET, using sterile swabs that were spread on the medium. Five cavities were made in each of two agar plates (total = 10) and completely filled with one of the calcium hydroxide pastes. The plates were preincubated for 1 h at environmental temperature and then incubated at 37 degrees C for 24 to 48 h. The inhibition zone around each well was recorded in millimeters, and the results were submitted to ANOVA and Tukey test (alpha = 0.05). All intracanal dressings induced inhibition zones (range 5.0-10.0 mm). Data obtained showed that both the DET and agar diffusion test are useful in establishing the calcium hydroxide antimicrobial spectrum, thus improving infection control protocols. The direct exposure method is independent of other variables and is a practical laboratory procedure. A complete antimicrobial effect was observed after 48 h on indicator microorganisms, in both tests, irrespective of the calcium hydroxide paste vehicle.

Marginal microleakage of class II composite resin restorations due to restorative techniques

PURPOSE: To evaluate the marginal microleakage of class II composite resin (CR) restorations due to restorative techniques. METHODS: Forty human extracted premolars were assigned to 4 groups (n=10). Class II cavities were prepared (4-mm wide, 2-mm axially, with the gingival margin located 1 mm beyond the cementum-enamel-junction), and the restorative adhesive system Prime & Bond 2.1/TPH3 (Dentsply) was used. CR was inserted by the oblique incremental technique (OIT) and cured in continuous exposure. The restoratives techniques were: group 1 (control): OIT; group 2: flowable resin (1 mm) applied in the gingival wall + OIT; group 3: OIT + three pre-cured spheres inserted in the first increment of CR; and, group 4: OIT + strip of fiberglass inserted in the first increment of CR. The specimens were subjected to a thermocycling regimen of 500 cycles (1 min at 5o-37o-55oC), coated with two layers of nail varnish up to 1 mm from the restoration margins, and immersed in 0.5% basic fuchsine solution for 24 h. The extension of dye penetration at the cervical wall (µm) was evaluated using an optic microscope at x40. Data were analyzed using analysis of variance (ANOVA) (α=0.05). RESULTS: The microleakage values were: G1: 370 µm ± 241; G2: 398 µm ± 354; G3: 205 µm ± 119; and G4: 413 µm ± 340. No statistically significant differences were found among the restorative techniques (P=0.081). CONCLUSION: Marginal microleakage values were not influenced by the different restorative techniques tested.

Characterization of the nucleus, cutting edge and failure detection in NiTi instruments for endodontic retreatment

OBJECTIVE: To characterize the nucleus, cutting edge and to detect defects in surfaces of nickeltitanium (NiTi) instruments for endodontic retreatment. METHODS: The selected endodontic instruments (D-RaCe, ProTaper retreatment and Mtwo retreatment) were evaluated prior to their use in 30- and 50-fold magnification in scanning electron microscopy (SEM), for linear measurements of lateral cut edge areas and of the nucleus and the ratio between these measures. After use in simulated canals, faults in the active surface were analyzed by SEM with 30 and 50 times magnification, and 200 times magnification when faults were found. The images were examined by three evaluators, whose measurements were previously calibrated. The defects analyzed were crack, blunt and barb, and data were tabulated for analysis. RESULTS: The instruments studied differed in results. The D-RaCe system instruments had the highest nucleus:edge ratio, while ProTaper retreatment instruments yielded the lowest ratio. All instruments presented some defect, with the instruments Mtwo retreatment presenting two instruments with defects. CONCLUSION: All analyzed instruments presented some type of failure after using them for removal of the filling material of simulated root canals. The D-RaCe system presented the highest edge measurements and the smallest nucleus measurements, contrary to the ProTaper retreatment system, which presented the smallest edge measurements and the largest core measurements.

Storage media for avulsed teeth: review of literature

Tooth avulsion is a traumatic injury which can cause severe consequences to permanent dentition,xa0because of the possible damage to periodontal structure. Immediate replantation is the bestxa0procedure. However, it sometimes cannot be performed and the success depends on the durationxa0of extra-alveolar time and storage medium of the tooth. The objective of this paper is to review thexa0literature about storage media due to its importance to replantation prognosis. Although innumerousxa0storage media have been tested until now, none of them has the biological requirements and isxa0available at the local accident. Saliva and water are easily accessible, although causing deleteriousxa0effects on periodontal cells. Growth factors have biological effects, though they are inaccessible.xa0Thus, its use is impracticable. Propolis and green tea extract seem to be promising and newxa0researches should be carried out. Milk, specially skimmed long shelf-life, seems to be a good optionxa0due to its cell viability good results besides its accessibility.