The combined use of Er,Cr:YSGG laser and fluoride to prevent root dentin demineralization

Abstract

The use of erbium lasers to prevent caries in enamel has shown positive results. However, it is not known if Er,Cr:YSGG laser can also be used to increase acid resistance of root dentine, which is another dental tissue susceptible to the action of cariogenic bacteria.ObjectiveTo analyze the effects of the Er,Cr:YSGG laser (λ=2.78 μm, 20 Hz) irradiation associated with 2% neutral sodium fluoride (NaF) to prevent root dentin demineralization.Material and MethodsOne hundred human root dentin samples were divided into 10 groups (G) and treated as follows: G1: no treatment; G2: NaF; G3: laser (4.64 J/cm2) with water cooling (WC=5.4 mL/min); G4: laser (4.64 J/cm2) without WC; G5: laser (8.92 J/cm2) with WC; G6: laser (8.92 J/cm2) without WC; G7: laser (4.64 J/cm2) with WC and NaF; G8: laser (4.64 J/cm2) without WC and NaF; G9: laser (8.92 J/cm2) with WC and NaF; G10: laser (8.92 J/cm2) without WC and NaF. The NaF gel was applied alone or after 4 min of irradiation. After 14 days of acid challenge, the samples were sectioned and the Knoop microhardness (KHN) test was done at different depths (30, 60, 90 and 120 μm) from the outer dentin surface. Data were analyzed by one-way ANOVA and Fisher's test (α=5%).ResultsThe results showed that G8 and G10 presented higher KHN than the G1 for the depths of 30 and 60 μm, indicating an increase of the acid resistance of the dentin in up to 35% (p<0.05).ConclusionsThe use of Er,Cr:YSGG laser irradiation at 4.64 J/ cm2 and 8.92 J/cm2 without water cooling and associated with 2% NaF can increase the acid resistance of human root dentin.

Relationship between Er,Cr:YSGG laser power and surface roughness of lased radicular dentin

“…Geraldo-Martin et al 18 (2013) showed that irradiation of Er,Cr:YSGG laser with 4.64 J/cm 2 energy density along with water coolant further opened the dentinal tubules; they concluded that use of water coolant during laser irradiation for prevention of caries in dentin is not much effective since it results in further opening of dentinal tubules, which probably leads to faster progression of caries in dentin. Later in 2014, Geraldo-Martin et al 2 showed that Er,Cr:YSGG laser irradiated with 8.92 J/cm 2 energy density without water coolant created brown spots on root dentin, which were microscopically shown to be burned dentin due to overheating. They demonstrated that high power Er,Cr:YSGG laser without water coolant caused significant thermal damage in dentin and made it more susceptible to acidic challenge.…”

“…Thus, laser irradiation must be necessarily accompanied by water-cooling to prevent damage to pulp and dentin; however, the amount of water must be minimal in order not to compromise the anti-caries effects of laser irradiation. 2 Therefore, we also used a combination of water (60%) and air (80%) coolant in our study. The chosen laser powers in our study (0.25, 0.5, 0.75 and 1W) were based on a previous study by de Freitas et al, 16 since these powers conferred optimal resistance to enamel in their study.…”

“…Hossain et al (2004) showed that Er,Cr:YSGG laser with 3-W power (70% air, 20% water, 33.9 J/cm 2 energy density) increased surface roughness of dentin. 23 Our findings revealed that Er,Cr:YSGG laser irradiation with 0.25- and 1-W powers(2.8 and 11.3J/cm 2 , respectively) increased the surface roughness compared to non-lased dentin surfaces, which was not significant; however, 0.5-W and 0.75-W powers of Er,Cr:YSGG laser decreased surface roughness compared to the control group (higher surface roughness of the control group was due to preparation of dentin with silicon carbide abrasive papers to remove cementum and denude root dentin). In our study, the only significant difference in surface roughness was noted between 0.5-W (lowest) and 1-W (highest) power groups.…”

“… 1 With tooth retention, older individuals are at a higher risk of denuded root surfaces, which might be due to periodontal diseases or mechanical traumas as a result of inappropriate plaque control measures and incorrect toothbrushing. 2 Root surface exposure associated with factors such as frequent use of carbohydrates, poor oral hygiene, low social class and reduced salivary flow in the elderly due to systemic diseases or drug use 3 - 5 often result in decreased pH and increased count of acidogenic microorganisms in the saliva and dental plaque 6 , 7 and subsequently increased risk of caries in denuded root surfaces.…”

Evaluation of diode laser along with 1.23% acidulated phosphate fluoride gel on dentinal tubule occlusion: An in vitro study

“…Earlier studies using other fluoride gels have been shown to significantly reduce dentinal hypersensitivity and improve dentinal tubule occlusion. [ 13 27 ]…”