Ultrasound device as a minimally invasive approach for caries dentin removal

Abstract The aim of this study was to evaluate the efficacy of an ultrasound device and the dentin surface morphology after removal of the caries dentin lesions by removal rate and scanning electron microscopy (SEM). The Knoop hardness test on the bovine dentin blocks (n = 20, 4x4x2mm) was performed to standardize the samples and only those with 38 ± 2 KHN were included. The dentin blocks were submitted to induction of artificial caries lesions, using the bacterial model. Strains of Streptococcus mutans and Lactobacillus acidophilus were used for 7 days. The caries dentin lesion was removed for 1 min, according to two methods: G1 - carbide bur under low-speed rotation (control group) and G2 - ultrasound device under refrigeration. For the removal rate, the samples were weighed 3 times: T0 (before induction), T1 (after induction) and T2 (after removal). Morphology evaluation of the residual dentin surface was performed by SEM. Data normality was verified by Shapiro-Wilk test (p ≥ 0.240). T-test for independent samples was applied to evaluate the removal rate. A significance level of 5% was adopted. G2 provided lower removal rate than G1 (G1: 3.68 mg and G2 = 2.26 mg). SEM images showed different morphological characteristics between the groups. G2 showed absent of smear layer, while G1 showed a visible smear layer over the surface. We concluded that ultrasound device provides minimally invasive removal with residual dentin exhibiting open dentin tubules and no smear layer formation and no bacteria, which infer the removal of the infected tissue.

Resumo O objetivo deste estudo foi avaliar a eficácia de um dispositivo ultrassônico e a morfologia da superfície dentinária após a remoção da dentina cariada por meio da taxa de remoção e imagens de microscopia eletrônica de varredura (MEV). Foi realizado o teste de dureza Knoop nas amostras de dentina bovina (n = 20, 4x4x2mm) afim de padronizar as amostras e foram incluídas apenas aquelas com 38 ± 2 KHN. As amostras de dentina foram submetidas à indução de lesões artificiais de cárie, utilizando-se modelo biológico contendo cepas de Streptococcus mutans e Lactobacillus acidophilus durante por 7 dias. As lesões foram removidas por 1 min, de acordo com dois métodos: G1 - fresa esférica sob baixa rotação (grupo controle) e G2 - dispositivo ultrassônico sob refrigeração. Para a taxa de remoção, as amostras foram pesadas em três tempos: T0 (antes da indução), T1 (após a indução) e T2 (após a remoção). A avaliação morfológica da superfície residual da dentina foi realizada por MEV. A normalidade dos dados foi verificada pelo teste de Shapiro-Wilk (p ≥ 0,240). Teste T para amostras independentes foi aplicado para avaliar a taxa de remoção. Foi adotado nível de significância de 5%. G2 apresentou menor taxa de remoção que G1 (G1: 3,68 mg e G2 = 2,26 mg). As imagens de MEV mostraram características morfológicas diferentes entre os grupos. G2 mostrou ausência de smear layer, enquanto G1 mostrou grande quantidade de smear layer sobre a superfície. Com base neste estudo in vitro, o dispositivo de ultrassom promoveu remoção minimamente invasiva e dentina residual exibindo túbulos dentinários abertos e mínima formação de smear layer.

Ultrasound power and irrigation volume in different lens opacity grades: comparison of femtosecond laser-assisted cataract surgery and conventional phacoemulsification

OBJECTIVES: To compare the amount of ultrasound energy and irrigation volume in conventional phacoemulsification cataract surgery versus femtosecond laser-assisted phacoemulsification at different nuclear-cortical cataract grades. METHOD: This was a prospective, consecutive, investigator-masked nonrandomized parallel cohort study. Patients were divided into 4 groups (Phaco1, Phaco2, Femto1 and Femto2) according to the surgical technique (conventional phacoemulsification [Group Phaco] or femtosecond laser-assisted cataract surgery [Group Femto]) and the Lens Opacity Classification System III (LOCS) grade (LOCS<11 [group 1] or LOCS≥11 [group 2]). The measured outcomes were effective phacoemulsification time (EPT), indicating the ultrasound energy, and balanced salt solution (BSS) use, indicating the irrigation volume, to indirectly estimate the damage to the corneal endothelium caused by the cataract surgery. RESULTS: A total of 160 eyes from 109 patients were included: 87 eyes in Group Phaco, 73 eyes in Group Femto, 76 eyes in group 1 and 84 eyes in group 2. The EPT mean in Femto1 was 53% less (2.73±1.88, 0.1 to 8.65) than that in Phaco1 (5.80±2.86) (p=0.00) and in Femto2 (8.38±9.32) was 33% less than that in Phaco2 (12.55±8.38) (p=0.00). No significant differences in mean LOCS grades between the Phaco1 (8.21±1.44) and Femto1 (7.90±1.90) groups (p=0.73) or between the Phaco2 (13.15±2.55) and Femto2 (12.72±2.18) groups (p=0.95) were found. There were no significant differences in the mean BSS use between the Phaco1 (55.73±12.45) and Femto1 (59.37±10.93) groups (p=0.48) or between the Phaco2 (64.34±21.00) and Femto2 (65.71±17.60) groups (p=0.47). CONCLUSIONS: Compared to conventional phacoemulsification at different nuclear-cortical cataract grades, femtosecond laser-assisted cataract surgery provides an EPT reduction but does not influence the BSS use.

Clinical effects of coaxial 1 . 8 mm microincision phacoemulsification / 国际眼科杂志(Guoji Yanke Zazhi)

AIM:To observe and compare clinical effects of coaxial 1. 8mm microincision phacoemulsification and 3. 2mm small incision phacoemulsification. ●METHODS:A total of 117 eyes of 85 patients with age-related cataract in our hospital were divided randomly into two groups:43 patients (59 eyes) in the coaxial 1. 8 mm microincision cataract surgery group ( C - MlCS ) , 42 patients (58 eyes) in the coaxial 3. 2 mm traditional small incision cataract surgery group (C-SlCS). A total of 117 eyes were received phacoemulsification with intraocular lens implantation. Uncorrected visual acuity was recorded preoperatively and postoperatively at 1, 7, 30 and 90d. The effective phacoemulsification time and average ultrasound energy were recorded in surgery. Corneal endothelial cell and corneal topography were recorded preoperatively and postoperatively at 90 d. ●RESULTS:Uncorrected visual acuity ( logMAR) was no overall statistical significance difference between C-MlCS group and C-SlCS group (P>0. 05), but was significant statistical difference in different time-point within both groups(P0. 05). On the 1 day after surgery, uncorrected visual acuity was 0. 16±0. 11 in C-MlCS group and 0. 22±0. 18 in C-SlCS group(P0. 05). EPT was (3. 09±1. 61)s in C-MlCS group and (3. 20±1. 92)s in C-SlCS group (P>0. 05). At 90 d after surgery, corneal endothelial cell loss percentage was (5. 81±2. 28)% in C-MlCS group and (5. 69±2. 38)% in C-SlCS group (P>0.05), SlA was (0.35±0.11) Din C-MlCS group and (0. 61±0. 13) D in C-SlCS group (P ● CONCLUSION: Compared with coaxial 3. 2mm traditional small incision cataract surgery, 1. 8mm coaxial microincision cataract surgery can get earlier visual rehabilitation and significantly reduce SlA. The coaxial 1. 8mm microincision cataract surgery is safe, effective and deserves further clinical applications.