RESUMO
PURPOSE: This systematic review provides an overview of the main chemical and morphological alterations generated on dentin by different high-power lasers' irradiation. METHODS: The review was registered in PROSPERO (CRD42023394164) and PRISMA guidelines were followed. The search strategy was conducted on MEDLINE (PubMed), Embase (Elsevier), and Web of Science (Clarivate) databases. The eligibility criteria were established according to the PICOS strategy, focusing on in vitro and ex vivo studies that assessed the chemical and morphological changes in dentin using five high-power lasers: Nd:YAG (1064 nm), Er:YAG (2940 nm), Er, Cr:YSGG (2780 nm), diode (980 nm), and CO2 (10,600 nm). Publication range was from 2010 to 2022. Data was summarized in tables and risk of bias was assessed by QUIN tool. RESULTS: The search resulted in 2255 matches and 57 studies composed the sample. The methods most used to assess the outcomes were scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and Raman. The studies presented "medium" and "low" risk of bias. The laser prevalently identified was the Er:YAG laser, associated with dentin ablation, absence of smear layer, and exposed tubules. The Nd:YAG laser generated vitreous surface and thermal damage, such as carbonization and cracks. The other lasers caused an irregular surface and no adverse thermal effects. Regarding the chemical structure, only the Er,Cr:YSGG laser caused collagen matrix reduction. The effects found were more intense with higher dosimetry. CONCLUSION: Evidence available indicates that the irradiation of dentin with high-power lasers are related to morphological outcomes favorable to adhesive restorative procedures, with minimal changes in collagen matrix and mineral content. However, those observations should be carried carefully by clinicians and more clinical trials regarding the association of high-power laser irradiation and restorative procedure longevity are needed.
Assuntos
Dentina , Lasers de Estado Sólido , Dentina/efeitos da radiação , Microscopia Eletrônica de Varredura , Espectrometria por Raios X , ColágenoRESUMO
Morphology study of root canal systems is essential for a correct diagnosis, therapy and prognosis of root canal treatment. This study aimed to analyse the dental anatomy of the lower anterior teeth, using cone-beam computed tomography (CBCT). Lower anterior teeth were classified in terms of type, number and location of root canals, evaluating the bilaterality of anatomical occurrences and determining whether the gender and age influence the findings. We analysed 749 CBCT of patients attending the School of Dentistry for different reasons. Spearman's correlations and Wilcoxon signed-rank test were used to analyse data (α = 0.05). There was no significant correlation between gender (male and female) and anatomy of the canals 33 (P = 0.162), 32 (P = 0.815), 31 (P = 0.708), 41 (P = 0.422), 42 (P = 0.382) and 43 (P = 0.063). There was a significant correlation between age and anatomy of the canals 33 (P = 0.045), 32 (P = 0.033), 31 (P = 0.022), 41 (P = 0.000), 42 (P = 0.037) and 43 (P = 0.037). There was no significant correlation between gender and patients' age (P = 0.325). There was no anatomical difference between the bilateral pairs (right and left homologous teeth) (P > 0.05). The most common anatomical configuration was single-canal teeth (85.29%), followed by the configuration in which one canal leaves the chamber, divides into two and unite again (12.88%). Anatomy of the lateral incisors and lower canines does not change with the gender of patients. However, as age rises, single canals and the incidence of division into two canals ending in a single foramen also increases.
Assuntos
Tomografia Computadorizada de Feixe Cônico , Feminino , Humanos , MasculinoRESUMO
The aim of this study was to evaluate the effect of Er:YAG laser for selective removal of carious lesion, followed by biomodification with chitosan gel where the subsurface microhardness, chemical composition, and morphological changes of the residual caries-affected dentin were examined. Artificial dentinal lesions were created by pH-cycling method (14 days) in 104 bovine specimens (5 × 5 mm). Specimens were randomly divided according to the carious removal method: bur (low-speed handpiece) or Er:YAG laser (250 mJ/4 Hz). Specimens were treated with 35% phosphoric acid and were subdivided into two groups according to dentin biomodification: without chitosan (control) and 2.5% chitosan. Forty specimens were restored with an adhesive system and composite resin. Subsurface microhardness tests were performed in sound dentin, caries-affected dentin, residual caries-affected dentin, and after the restoration. The other 64 specimens were subjected to SEM-EDS atomic analysis. Data were statistically analyzed (p < 0.05). After the Er:YAG laser excavation, the microhardness value of residual caries-affected dentin was higher (p < 0.05) than bur-treated dentin. A significant decrease in the amount of Ca, P, and Ca/P ratio was found after the removal of carious lesions with Er:YAG laser (p < 0.05). The biomodification with chitosan did not influence the microhardness and atomic percentage of Ca, P, and Ca/P ratio of residual caries-affected dentin (p > 0.05). SEM analysis showed morphological changes on residual caries-affected dentin (p > 0.05). The selective removal of carious dentin with Er:YAG laser increased microhardness of residual caries-affected dentin, changing its surface morphology and chemical composition. The biomodification with chitosan did not influence the structural and chemical composition of residual caries-affected dentin.
Assuntos
Quitosana/farmacologia , Cárie Dentária/cirurgia , Dentina/efeitos da radiação , Lasers de Estado Sólido/uso terapêutico , Animais , Bovinos , Intervalos de Confiança , DurezaRESUMO
BACKGROUND: It remains unclear as to whether or not dental bleaching affects the bond strength of dentin/resin restoration. PURPOSE: To evaluated the bond strength of adhesive systems to dentin submitted to bleaching with 38% hydrogen peroxide (HP) activated by LED-laser and to assess the adhesive/dentin interfaces by means of SEM. STUDY DESIGN: Sixty fragments of dentin (25 mm²) were included and divided into two groups: bleached and unbleached. HP was applied for 20 s and photoactivated for 45 s. Groups were subdivided according to the adhesive systems (n = 10): (1) two-steps conventional system (Adper Single Bond), (2) two-steps self-etching system (Clearfil standard error (SE) Bond), and (3) one-step self-etching system (Prompt L-Pop). The specimens received the Z250 resin and, after 24 h, were submitted to the bond strength test. Additional 30 dentin fragments (n = 5) received the same surface treatments and were prepared for SEM. Data were analyzed by ANOVA and Tukey's test (α = 0.05). RESULTS: There was significant strength reduction in bleached group when compared to unbleached group (P < 0.05). Higher bond strength was observed for Prompt. Single Bond and Clearfil presented the smallest values when used in bleached dentin. SEM analysis of the unbleached specimens revealed long tags and uniform hybrid layer for all adhesives. In bleached dentin, Single Bond provided open tubules and with few tags, Clearfil determined the absence of tags and hybrid layer, and Prompt promoted a regular hybrid layer with some tags. CONCLUSIONS: Prompt promoted higher shear bond strength, regardless of the bleaching treatment and allowed the formation of a regular and fine hybrid layer with less deep tags, when compared to Single Bond and Clearfil.
Assuntos
Resinas Compostas/química , Cimentos Dentários/química , Dentina/química , Peróxido de Hidrogênio/farmacologia , Clareamento Dental/efeitos adversos , Adesividade/efeitos dos fármacos , Resinas Compostas/análise , Colagem Dentária , Restauração Dentária Permanente , Análise do Estresse Dentário , Dentina/fisiologia , Dentina/ultraestrutura , Humanos , Peróxido de Hidrogênio/química , Microscopia Eletrônica de Varredura/métodos , Dente/efeitos dos fármacos , Clareamento Dental/métodosRESUMO
BACKGROUND: The topographical features of intraradicular dentine pretreated with sodium hypochlorite (NaOCl) or ethylenediamine tetraacetic acid (EDTA) followed by diode laser irradiation have not yet been determined. PURPOSE: To evaluate the alterations of dentine irradiated with 980-nm diode laser at different parameters after the surface treatment with NaOCl and EDTA. STUDY DESIGN: Roots of 60 canines were biomechanically prepared and irrigated with NaOCl or EDTA. Groups were divided according to the laser parameters: 1.5 W/CW; 1.5 W/100 Hz; 3.0 W/CW; 3.0 W/100 Hz and no irradiation (control). The roots were splited longitudinally and analyzed by scanning electron microscopy (SEM) in a quali-quatitative way. The scores were submitted to two-way Kruskal-Wallis and Dunn's tests. RESULTS: The statistical analysis demonstrated that the specimens treated only with NaOCl or EDTA (control groups) were statistically different (P < 0.05) from the laser-irradiated specimens, regardless of the parameter setting. The specimens treated with NaOCl showed a laser-modified surface with smear layer, fissures, and no visible tubules. Those treated with EDTA and irradiated by laser presented absence of smear layer, tubules partially exposed and melting areas. CONCLUSIONS: The tested parameters of 980-nm diode laser promoted similar alterations on dentine morphology, dependent to the type of surface pretreatment.