Er:YAG laser cavity preparation and composite resin bonding with a single-component adhesive system: relationship between shear bond strength and microleakage

Comparative Assessment of Marginal Micro Leakage of Different Esthetic Restorative Materials Used on Primary Teeth: An In-vitro Study

AIM

The aim of the current investigation was to evaluate the marginal microleakage of various esthetic restorative materials applied to primary teeth.

MATERIALS AND METHODS

A total of 75 noncarious primary molars that were removed for orthodontic intervention and teeth nearing exfoliation were chosen. One millimeter (mm) above the cementoenamel junction, on the buccal surface of the teeth, Class V cavities were prepared. William's graded periodontal probe was used to standardize cavity preparation on all teeth. 3 mm was the cavity's length, 2 mm in width, and 2 mm in depth. The teeth were then divided into three groups (25 samples in each group) according to the type of esthetic restorative material used. Group I: Resin-modified glass ionomer cement, Group II: Ormocer, Group III: Giomer. The samples underwent 500 cycles of thermocycling, with an immersion time of 60 seconds and a well time of 15 seconds, between 5 and 55°C. The samples were submerged in methylene blue dye for 24 hours at room temperature and dried. The samples were then divided into sections and examined with a stereomicroscope. Data was recorded and statistically analyzed.

RESULTS

The least marginal microleakage was found in the ormocer group (1.22 ± 0.01) followed by resin-modified glass ionomer cement group (1.31 ± 0.07) and the giomer group (1.78 ± 0.03). There was a highly statistically significant difference found between resin-modified glass ionomer cement group and the ormocer group, resin-modified glass ionomer cement group and giomer group. And no significant difference was found between the ormocer group and the giomer group.

CONCLUSION

The present study concluded that there was some amount of microleakage in primary teeth in all restorative materials examined in this in-vitro investigation. However, the marginal sealing ability of ormocer was found highest compared to resin-modified glass ionomer cement and Giomer materials.

CLINICAL SIGNIFICANCE

The primary reason dental restorations fail, particularly in Class V cavities, is microleakage since the margins of these restorations are typically found in the dentin or cementum. Assessing microleakage is a crucial step in determining the marginal integrity of restorative materials. Developing methods and resources that reduce the adverse effects caused by the restorative marginal seal failing would benefit from this. How to cite this article: Al Ghwainem A, Alqarni AS. Comparative Assessment of Marginal Micro Leakage of Different Esthetic Restorative Materials Used on Primary Teeth: An In-vitro Study. J Contemp Dent Pract 2024;25(1):58-61.

Clinical effects of laser-based cavity preparation on class V resin-composite fillings

The aim of the present clinically controlled two-year study was to investigate the influence of laser-based cavity preparation on the long-term performance of Class V resin-composite fillings. Class V non-carious lesions (n = 75) were randomly assigned to two test and one control group. Cavities in both test groups were prepared using an Er,Cr:YSGG laser (Waterlase MD, Biolase, Irvine, California, USA). The device was operated at 3 W (150 mJ, 30 J/cm²), 50% water, 60% air, 30 Hz in H mode. Subsequently, laser-prepared tooth surfaces in test group I (n = 21) were additionally conditioned by acid etching (etch-and-rinse). Laser-prepared cavities of test group II (n = 21) received no additional acid conditioning. After application of an adhesive, all cavities were restored using the resin-composite Venus®. For cavities in the control group (n = 33) conventional diamond burs were used for preparation which was followed by an etch-and-rinse step, too. The fillings were evaluated immediately (baseline) and after 6, 12 and 24 months of wear according to the C-criteria of the USPHS-compatible CPM-index. The results showed that after 24 month of wear, laser-preparation was associated with fillings of high clinical acceptability. Compared to conventional bur-based treatment, laser-based cavity preparation resulted in fillings with high marginal integrity and superior marginal ledge configurations (p = 0.003). Furthermore, laser-preparation combined with additional acid-conditioning (test group I) resulted in fillings with the best marginal integrity and the lowest number in marginal discoloration, especially at the enamel-composite margins (p = 0.044). In addition, total loss of fillings was also less frequently observed in both laser groups as compared to the control. The results clearly demonstrate that laser-based cavity preparation will benefit the clinical long-time performance of Class V resin-composite fillings. Furthermore, additional acid-conditioning after laser preparation is of advantage.

Comparative Evaluation of Microleakage of Bioactive, Ormocer, and Conventional GIC Restorative Materials in Primary Molars: An In Vitro Study Microleakage of Three Restorative Materials

This in vitro study aimed to evaluate and compare the microleakage of bioactive, ormocer, and conventional glass ionomer cement (GIC) restorative materials in primary molars. In this study, class V cavities were prepared on the buccal surface of 75 noncarious extracted primary molars. The teeth were then restored as per the groups assigned. Group A, group B, and group C used bioactive restorative materials, ormocer restorative materials, and conventional GIC restorative materials for restorations, respectively. The teeth were then thermocycled and subjected to microleakage analysis via dye penetration. The microleakage scores were compared for differences using the Kruskal–Wallis test. This was followed by multiple pairwise comparisons using the Dunn test. All testing was carried out using a ‘p’ value of <0.05. The percentage of samples showing microleakage score 0 depicting no dye penetration was highest for group A (56%) followed by group C (44%) and group B (12%). Statistical analysis revealed highest microleakage with group B, which was statistically significant ( $p$  < 0.05). Microleakage was evident in all the materials tested. The lowest microleakage was seen with bioactive restorative material.

Effect of different types of adhesive systems on the bond strength and marginal integrity of composite restorations in cavities prepared with the erbium laser-a systematic review

There are inconclusive results regarding etching and bonding protocol to achieve optimal bond strength and marginal integrity of adhesive composite resin restorations in erbium laser prepared cavities. This systematic review aimed to consider which adhesive system protocol may be optimal in achieving the bond strength and marginal integrity in erbium laser-prepared cavities, comparable to that obtained with conventional method of cavity preparation. This review was developed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement with literature search based on all publications during the period January1, 2000-October 10, 2020, in three databases: MEDLINE, Google Scholar and ScienceDirect. The necessary information was extracted by two independent authors. The search resulted in 139 articles from all databases, and a total of thirty-one articles met the inclusion criteria. The results indicated that the selection of adhesives depending on their pH and composition and the laser pulse duration and pulse energy used plays an important role in predicting the adhesion and marginal integrity. The 10-MDP containing moderate self-etch adhesives has demonstrated predictable outcomes. Longer pulse durations used for cavity preparations may indicate the use of etch-and-rinse (EnR) or moderate self-etch adhesives (SEA) to allow better resin infiltration in deep craters formed due to laser irradiation. However, further studies with more standardizations in relation to adhesives and laser parameters are needed.

Shear bond strength of acid and laser conditioned enamel and dentine to composite resin restorations: An in vitro study

Objective

To compare the shear bond strength of enamel or dentin conditioned with either Er,Cr:YSGG (erbium, chromium: yttrium–scandium–gallium–garnet) laser or phosphoric acid to composite resin restoration.

Material and methods

Forty posterior human extracted teeth were used. After mesiodistal sectioning of the teeth crowns, the samples were randomly divided into two groups—in the first group (E), bonding was performed on the enamel after roughening and in the second group (D), the enamel was removed and bonding was performed on the dentin. These groups were further randomly divided into two subgroups according to the type of etching (n = 20 each). In the acid‐etched groups (EA and DA), the surfaces were etched with 37% phosphoric acid. In the laser‐conditioned groups (EL and DL), the surfaces were conditioned with Er,Cr:YSGG laser. Total‐etch adhesive system was used to bond all the 80 specimens resin composite. The composite was vertically light‐cured, and the specimens were subjected to a shear bond strength test. Modes of bond failure were determined with a stereomicroscope.

Results

The highest shear bond strength was observed for the DA group (16.25 ± 1.10 MPa, p < 0.0001), whereas the lowest was observed for the DL group (8.56 ± 0.67 MPa). The adhesive failure mode was the most frequently observed in all groups.

Conclusions

The shear bond strength of composite resin bonded to enamel and dentin etched with phosphoric acid was higher than when conditioned with Er,Cr:YSGG laser. Thus, laser conditioning is not recommended.

Comparison of three adhesive systems in class II composite restorations in endodontically treated teeth: Influence of Er:YAG laser conditioning and gingival margin levels on microleakage

Background

Dental surface conditioning by Er:YAG laser is currently being investigated, as not all of the mechanisms and effects of this technique have been clearly studied. Thus, the aim of the present study was to assess the cervical microleakage of Class II resin composite restorations in endodontically treated teeth following either the respective conventional conditioning or additional Er:YAG laser conditioning, in association with varied adhesives.

Material and Methods

Standardized mesial-occlusal-distal cavities (two gingival walls positioned in dentin and enamel, respectively) were created in 60 extracted human premolar teeth. Following the completion of the endodontic therapy, the teeth were grouped into six categories based on conditioning modality and adhesive strategy as follows: group 1-37% phosphoric acid/Adper Single Bond 2 (ASB2); group 2-Er:YAG laser/37% phosphoric acid/ASB2; group 3-Clearfil SE Bond (CSE); group 4-Er:YAG laser/CSE; group 5-Adper Easy One (AEO); and group 6-Er:YAG laser/AEO. Specimens were submitted to thermocycling and dye penetration, followed by longitudinal sectioning. The dye penetration was evaluated using a stereomicroscope. One specimen from each group was assessed under a scanning electron microscope for adhesive interface analysis.

Results

No significant differences were found between the conditioning modalities, nor between the adhesive systems at both margins. Groups 1 and 2 showed a lower degree of microleakage in the enamel vs. dentin (p = 0.002). Group 2 showed a significantly lower incidence of microleakage in enamel vs. dentin (p = 0.005).

Conclusions

CSE and AEO were comparable with that of ASB2 regarding sealing ability. Additional Er:YAG laser conditioning may be beneficial before ASB2 application in enamel.

Key words:Endodontically treated teeth, etch-and-rinse adhesive, Er:YAG laser, gingival level, sealing ability, self-etch adhesive.

Effect of Nd:YAG Laser Irradiation Pretreatment on the Long-Term Bond Strength of Etch-and-Rinse Adhesive to Dentin

PURPOSE

To investigate the effect of neodymium-doped yttrium aluminum garnet (Nd:YAG) laser irradiation pretreatment on the long-term bond strength of an etch-and-rinse adhesive to dentin.

METHODS

Fifty molars were sectioned parallel to the occlusal plane and randomly divided into two groups (n=25 per group): control group (no treatment) and laser group (dentin surfaces were treated with Nd:YAG laser at a setting of 100 mJ/10 Hz). Afterward, resin was bonded to the dentin surface using a two-step etch-and-rinse adhesive (Adper SingleBond 2), and then 150 beams of each group were produced. Each group was divided into three subgroups (n=50 each group): 24 hours of water storage, thermocycling, and NaOCl storage. The microtensile bond strength (MTBS), failure modes, nanoleakage expression, and Masson's trichrome staining were evaluated. An additional 20 molars were sectioned to obtain 2-mm-thick flat dentin slices. These slices were randomly divided into control and laser-treated groups as mentioned previously. Then slices of each group were examined by scanning electron microscopy, attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), X-ray diffraction (XRD), and the Knoop hardness test.

RESULTS

The results of ATR-FTIR and Masson's trichrome verified that laser irradiation partly removed collagen fibers from the dentin surface; however, no significant difference was found in the Knoop hardness (p>0.05). The XRD result showed similar crystalline structure regardless of laser pretreatment. There is no significant difference in short-term MTBS between control and laser-treated groups (p>0.05); however, long-term MTBS differed between the groups (p>0.05). Furthermore, the laser-treated group showed less silver deposition than the control group after aging (p<0.05).

CONCLUSION

Pretreatment by Nd:YAG laser irradiation appeared to have a positive effect on the adhesive-dentin bonding in vitro test, and the bonding effectiveness could be preserved after aging.

Use of erbium laser in the treatment of persistent post-radiotherapy laryngeal edema: a case report and review of the literature

BACKGROUND

Post-radiotherapy laryngeal edema may affect the patients' quality of life, leading to repeated treatment attempts, which include massage/physical therapy, inhalations, and/or tracheostomy.

CASE PRESENTATION

We report the surgical treatment approach of a 69-year-old patient with severe persistent post-radiotherapy laryngeal edema. After multiple inpatient admissions and failed conservative therapy, we used the erbium laser to treat the arytenoid edema. After repeated procedures, no complications were observed. The patient remained free of symptoms after 30 months of follow-up.

CONCLUSIONS

The authors provide an easy-to-perform, safe, and quick surgical technique without non-severe or severe complications. Using this technique repeatedly, complications from excessive thermal damage with CO₂ laser or unpleasant solutions such as tracheostomy can be avoided.

Effect of Erbium-yttrium, scandium, gallium and garnet (Er-YSGG) laser on the bond strength of lithium disilicate ceramics

Objectives

To assess the bond strength of LD ceramics with resin composite material and surface conditioning using Er: YSGG laser and HF acid.

Methods

Thirty LD ceramic (Emax, Ivoclar vivadent) discs were prepared using hot pressing technique and treated with hydroflouric acid (Group-1-HF acid) (9%) (n=10) and Er- yttrium, scandium, gallium and garnet laser (Group-2-ER-YSGG laser) (Waterlase iPlus, 10 Hz and power of 0.5 W, pulse duration of 230 μs) (n=10). Ten specimens were left untreated to be included as controls (Group-3-Control). All the specimens were treated with Adper Single Bond adhesive (3MESPE, St. Paul, MN, USA). Multicore buildups (3mmx3mm) were performed using a rubber mold on the ceramic surfaces and cured using LED light-curing unit for 140 sec. All specimens were tested using shear bond test and failure modes were assessed with a stereomicroscope and scanning electron microscope. Data was analysed using ANOVA and Tukey Kramer multiple comparisons test.

Results

The maximum and minimum shear bond strength values were achieved in HF Acid specimens (Group-1) (28.15±4.72 MPa) and control specimens (13.47± 3.14 MPa) respectively. Specimens treated with HF acid showed significantly higher bond strength in comparison to laser treated and control specimens (p<0.01). Laser treated specimens had significantly higher bond strength as compared to controls (p<0.01).

Conclusions

Hydrofluoric (HF) acid treatment showed significantly better outcomes than YSGG laser surface treatment.

Histological evaluation of three techniques for caries removal

A number of concepts and devices have been proposed for caries removal. Among these, the Er:YAG laser is a potential alternative to conventional mechanical treatment. This study compared the effectiveness of the Er:YAG laser with that of low-speed rotary instruments for removal of carious tissue in 26 extracted human molars and premolars with severe decay (i.e., large occlusal or proximal decay but no pulpal contact). The teeth were divided into three groups of eight teeth, and two teeth were used as controls. After sectioning all the teeth through the center of the carious lesion before excavation, each group was randomly assigned to three groups-Er:YAG laser versus tungsten bur, Er:YAG laser versus polymer bur, and polymer bur versus tungsten bur-to evaluate the efficacy of the three techniques. The time required for carious treatment of each half was recorded, and samples were then histologically examined. Mean duration of caries removal did not significantly differ in relation to the technique used. Histological analysis of tooth halves treated with the Er:YAG laser revealed a regular 5-µm-thick stained layer that appeared to be denatured collagen. A smear layer was often detectable in halves treated with carbide burs. A superficial disorganized layer, which was found to be affected dentin, was observed in halves treated with polymer burs. The present findings indicate that the three techniques were clinically and histologically effective in removing the infected dentin layer.(J Oral Sci 58, 583-589, 2016).

Effect of Laser Etching on Glass Fiber Posts Cemented with Different Adhesive Systems

BACKGROUND

Glass fiber-reinforced posts have been preferred frequently because of some physical properties similar to the dentin, chemically bonding to dentin, biocompatibility, and esthetics.

OBJECTIVE

This study aimed to evaluate the microleakage and bond strength of glass fiber posts cemented with various adhesive systems on laser-etched root canal walls.

METHODS

Roots of 120 human mandibular premolars were divided into two groups for push-out bond strength test and the microleakage test (n = 60). Erbium-doped yttrium-aluminum-garnet (Er:YAG) laser etching of the root canal walls was carried out on half of the specimens in both test groups. The laser-treated and laser-nontreated groups were divided again into three subgroups (n = 10). Glass fiber posts (everStick Post) were luted using three different resin cements: total-etch (Variolink N), self-etch (Panavia F 2.0), and self-adhesive (Rely X Unicem). Three dentin discs were obtained from each root, and the bond strength of the glass fiber posts was measured by push-out tests. The dye penetration method was used to investigate coronal microleakage. In addition, surface treatments and the bonding interfaces were observed using scanning electron microscope.

RESULTS

The highest bond strengths were observed for the total-etch and self-adhesive resin cement groups with laser etching (p < 0.05), and the lowest bond strength was obtained for the self-etch resin cement group (p < 0.05). There were no statistically significant differences in terms of microleakage (p > 0.05), except for the self-adhesive resin cement group (p < 0.05).

CONCLUSIONS

Er:YAG laser etching enhances the bonding strength of glass fiber posts. In addition, laser etching can reduce microleakage of self-adhesive resin cement.

Investigation of the Er: YAG laser and diamond bur cavity preparation on the marginal microleakage of Class V cavities restored with different flowable composites

The purpose of this study was to evaluate the efficiency of the Er:YAG laser and diamond bur cavity preparation on the marginal microleakage of Class V cavities. Group 1: bur preparation (bp) + Vertise Flow (VF); Group 2: laser preparation (lp) + VF; Group 3: bp + Adper Easy One (AEO) + Filtek Ultimate Flowable Composite (FUFC); Group 4: lp + AEO + FUFC; Group 5: bp + Clearfil S3 Bond (CSB) + Clearfil Majesty Flow (CMF); Group 6: lp + CSB + CMF. Data were analyzed by Kruskal-Wallis and Mann-Whitney U tests (p < .05). More microleakage was observed in cervical regions compared to occlusal regions in all groups (p < .05). No significant difference was observed among all groups in terms of occlusal and cervical surfaces, respectively (p > .05). The use of the Er:YAG laser for cavity preparation with different adhesive systems and flowable composites did not influence microleakage.

In vitro microleakage of class v composite restorations prepared by Er,Cr:YSGG laser and carbide bur

Background: The aim of this in vitro study was to compare the degree of microleakage on enamel and dentin margins of class V cavities prepared with either a high-speed drill or an Er,Cr:YSGG laser (2780 nm) and to associate their use with a beveling method for the margin. Method and Materials: Sixty bovine incisors were randomly distributed into three groups. Group 1 (G1) cavities were laser prepared and bur beveled, group 2 (G2) cavities were bur prepared and beveled, while cavities of group 3 (G3) were laser prepared and beveled. Cavities were restored with selective enamel etching, using the same bonding agent and nano-hybrid resin composite for all groups. After thermocycling, microleakage was assessed using a methylene blue dye penetration method. Results: Statistical analysis (Mann-Whitney, Kruskal-Wallis and post-hoc Dunn’s multiple comparison tests) demonstrated significantly higher microleakage for dentin compared to enamel margins in G1. Enamel margin microleakage was found to be significantly higher at G3 compared to G1 (p=0.032) and G2 (p=0.001), while no significant differences were found between G1 and G2 (p=0.850). Regarding dentin margins, G2 group performed significantly better than G1 and G3 (p<<0.001), while there was no significant difference among G1 and G3 scores (p=1.000). Conclusions: The conventional cavity preparation method seems to perform better in terms of microleakage than the Er,Cr;YSGG laser. Laser-prepared cavities could perform better in terms of microleakage if an additional step of enamel bur-beveling is performed prior to restoration.

Effect of different parameters of Er:YAG laser irradiations on class V composite restorations: A scanning electron microscopy study

The purpose of this study was to compare different parameters of Er:YAG laser irradiations on the marginal microleakage of Class V resin composite restorations. A total of 45 extracted premolars were selected for the study. Class V cavities prepared on both buccal and lingual surfaces of teeth by Er:YAG laser or bur and divided into nine groups. The occlusal margins were in enamel and the cervical margins were in cementum. Group-1: bur preparation; Group-2: laser preparation (lp) (600 mJ/5 Hz); Group-3: lp (300 mJ/10 Hz); Group-4: lp (200 mJ/15 Hz); Group-5: lp (150 mJ/20 Hz); Group-6: lp (200 mJ/20 Hz); Group-7: lp (300 mJ/14 Hz); Group-8: lp (400 mJ/10 Hz); Group-9: lp (700 mJ/5 Hz). All teeth were stored in distilled water at 37°C for 24 h, then thermocycled 1,000 times (5-55°C). Five teeth from each group were chosen for the microleakage investigation and two teeth for the scanning electron microscope (SEM) evaluation. Teeth, which were prepared for the microleakage test were immersed in 0.5% methylene blue dye for 24 h. After immersing, the teeth were sectioned and observed under a stereomicroscope for dye penetration. Data were analyzed by Kruskal-Wallis and Mann-Whitney U tests (p < 0.05). More microleakage was observed in cervical regions compared to occlusal regions in all groups (p < 0.05) except for Group 6 (p > 0.05). No significant difference was observed among groups in terms of occlusal and cervical surfaces, separately (p > 0.05). It may be concluded that the cavities prepared by Er:YAG laser showed higher degree of microleakage than bur prepared at cervical regions. Different parameters of Er:YAG laser irradiations affected microleakage. SCANNING 38:434-441, 2016. © 2016 Wiley Periodicals, Inc.

Comparison of total-etch, self-etch, and selective etching techniques on class V composite restorations prepared by Er:YAG laser and bur: a scanning electron microscopy study

The purpose of this study was to compare total-etch, self-etch, and selective etching techniques on the marginal microleakage of Class V composite restorations prepared by Er:YAG laser and bur. Class V cavities prepared on both buccal and lingual surfaces of 30 premolars by Er:YAG laser or bur and divided into six groups. The occlusal margins were in enamel, and the cervical margins were in cementum. Group-1: bur preparation(bp)+Adper Single Bond 2 (ASB)+Filtek Z550 (FZ); Group-2: laser preparation(lp)+(ASB)+(FZ); Group-3: bp + Clearfil S3 Bond Plus (CSBP)+(FZ); Group-4: lp+(CSBP) (FZ); Group-5: bp + acid etching+(CSBP)+(FZ); Group-6: lp + acid etching+(CSBP)+(FZ). All teeth were stored in distilled water at 37°C for 24 hr, and then thermocycled 1000 times (5-55°C). Five teeth from each group were chosen for the microleakage investigation, and two teeth for the scanning electron microscope evaluation. Teeth which were prepared for the microleakage test were immersed in .5% methylene blue dye for 24 hr. After immersion, the teeth were sectioned and observed under a stereomicroscope for dye penetration. Data were analyzed using Kruskal-Wallis and Mann-Whitney U tests (p < .05). More microleakage was observed in the cervical regions compared to the occlusal regions in Groups 3, 5, and 6, respectively (p < .05). There is no statistically significant difference in Groups 1, 2, and 4, in terms of cervical regions versus occlusal regions (p > .05). No significant differences were observed among any groups in terms of occlusal and cervical surfaces, separately (p > .05). Different etching techniques did not influence microleakage of Class V restorations prepared by Er:YAG laser and bur.

Assessment of Microleakage of a Composite Resin Restoration in Primary Teeth Following Class III Cavity Preparation Using Er, Cr: YSGG laser: An In Vitro Study

Introduction: Marginal seal integrity is important for a successful adhesive dental restoration. Alterations caused by laser irradiation in the enamel and dentin surface can affect the marginal integrity of adhesive restorations. The aim of this study was to evaluate the microleakage of a composite resin restoration in primary teeth following laser irradiation of enamel and dentin. Methods: Forty freshly extracted sound human primary maxillary and mandibular anterior teeth were used in this study. The teeth were randomly divided into two groups (I and II), with 20 teeth in each. In group I, proximal cavities (Class III) were prepared using an airotor hand -piece and diamond bur. The cavities were etched for 15 seconds with 35% phosphoric acid gel, rinsed with water for 15 seconds, air dried and a bonding agent was applied onto the cavity surfaces and light cured for 20 seconds. The cavities were restored with composite resin and light cured for 40 seconds. In group II, proximal (Class III) cavities were prepared using Erbium, Chromium: Yttrium Scandium Gallium Garnet (Er,Cr:YSGG) (Er,Cr:YSGG) (Biolaseiplus, wave length 2.78 μm). The cavity was then rinsed, air dried and without etching, a bonding agent was applied and light cured for 20 seconds. The cavities were restored in the same manner as that of group I. The treated teeth were mounted on acrylic resin blocks and were subjected to a thermocycling regimen. Following, the teeth were immersed in 2% methylene blue for 24 hours. The teeth were sectioned longitudinally in a bucco-lingual direction using a diamond disc at slow speed. The sections of all the groups were examined under a stereomicroscope for micro-leakage. Results: The mean scores for microleakage in group I was 1.95 ± 1.31 and in group II it was 1.4 ± 1.27. There was no significant difference between the two groups (P = 0.882). Conclusion: No significant difference in microleakage was noticed between the composite resin bonded to lased enamel and dentin and the teeth preparedwith conventional method.

A Comparative Study of Microleakage on Dental Surfaces Bonded with Three Self-Etch Adhesive Systems Treated with the Er:YAG Laser and Bur

Aim. This study sought to compare the microleakage of three adhesive systems in the context of Erbium-YAG laser and diamond bur cavity procedures. Cavities were restored with composite resin. Materials and Methods. Standardized Class V cavities were performed in 72 extracted human teeth by means of diamond burs or Er-YAG laser. The samples were randomly divided into six groups of 12, testing three adhesive systems (Clearfil s³ Bond Plus, Xeno® Select, and Futurabond U) for each method used. Cavities were restored with composite resin before thermocycling (methylene blue 2%, 24 h). The slices were prepared using a microtome. Optical microscope photography was employed to measure the penetration. Results. No statistically significant differences in microleakage were found in the use of bur or laser, nor between adhesive systems. Only statistically significant values were observed comparing enamel with cervical walls (p < 0.001). Conclusion. It can be concluded that the Er:YAG laser is as efficient as diamond bur concerning microleakage values in adhesive restoration procedures, thus constituting an alternative tool for tooth preparation.

Effect of CO2, Nd:YAG and Er:YAG Lasers on Microtensile Bond Strength of Composite to Bleached-Enamel

Background:

Tooth restoration immediately after bleaching is challenging due to the potential problems in achieving adequate bond strength.

Objective:

The aim of this study was to evaluate the effect of surface treatment with ER:YAG, ND:YAG, CO₂ lasers and 10% sodium ascorbate solution on immediate microtensile bond strength of composite resin to recently bleached enamel.

Materials & Methods:

Ninety sound molar teeth were randomly divided into three main groups (n:30) : NB (without bleaching), HB (bleached with 38% carbamide peroxide) and OB (bleached with Heydent bleaching gel assisted by diode laser). Each group was divided into five subgroups (n:6) : Si (without surface treatment), Er (Er:YAG laser), CO₂ (CO₂ laser), Nd (Nd:YAG laser) and As (Immersion in 10% sodium ascorbate solution). The bonding system was then applied and composite build-ups were constructed. The teeth were sectioned by low speed saw to obtain enamel- resin sticks and submitted to microtensile bond testing. Statistical analyses were done using two- way ANOVA, Tukey and Tamhane tests.

Results:

µTBS of bleached teeth irradiated with ND:YAG laser was not significantly different from NB-Nd group. Microtensile bond strength of OB-Er group was higher than NB-Er and HB-Er groups. The mean µTBS of HB-CO₂ group was higher than NB-CO₂ group; the average µTBS of HB-As and OB-As groups was also higher than NB-As group.

Conclusion:

Use of Nd:YAG, CO₂ lasers and 10% sodium ascorbate solution could improve the bond strength in home-bleached specimens. Application of ND:YAG laser on nonbleached specimens and Er:YAG laser on office-bleached specimens led to the highest µTBS in comparison to other surface treatments in each main group.

Evaluation of the Morphological Characteristics of Laser-Irradiated Dentin

OBJECTIVE

The aim of this study was to investigate the effect of different energy settings of Er:YAG laser irradiation on dentin surface morphology with respect to the number of opened dentinal tubules.

BACKGROUND DATA

An ideally prepared dentin surface with opened dentinal tubules is a prerequisite for adhesive fixation. No study, however, has yet compared the numbers of opened dentinal tubules with regard to statistical differences.

METHODS

Conventional preparations using a bur with or without additional acid etching acted as control groups. Dentin specimens were prepared from human third molars and randomly divided into eight groups according to the energy settings of the laser (1, 1.5, 4, 6, 7.5, and 8 W) and two controls (bur and bur plus acid etching). After surface preparation, dentin surfaces were analyzed with a scanning electron microscope, and the number of opened dentinal tubules in a defined area was counted.

RESULTS

The control groups showed smooth surfaces with (bur plus acid etching) and without opened dentinal tubules (bur), whereas all laser-irradiated surfaces showed rough surfaces. Using the energy setting of 4 W resulted in significantly more opened dentinal tubules than the conventional preparation technique using the bur with additional acid etching. In contrast, the energy setting of 8 W showed significantly fewer opened dentinal tubules, and also exhibited signs of thermal damage.

CONCLUSIONS

The Er:YAG laser with an energy setting of 4 W generates a dentin surface with opened dentinal tubules, a prerequisite for adhesive fixation.

Microleakage of Self-Etch Adhesive System in Class V Cavities Prepared by Using Er:YAG Laser with Different Pulse Modes

OBJECTIVE

In vitro studies evaluated cementum surface morphology and microleakage of three different energy density parameters of Erbium: Yttrium Aluminum Garnet (Er:YAG) laser compared with diamond bur preparation on class V cavities with self-etch adhesive system and composite resin restoration.

MATERIAL AND METHODS

Standard class V cavities were prepared at cervical area below the cementoenamel junction (CEJ) in 80 extracted premolars, by using a diamond bur on the buccal surface. All teeth were randomly allocated into four groups: Group 1, diamond bur; Group 2, Er:YAG 50 mJ/15 Hz, 3.77 J/cm(2); Group 3, Er:YAG 75 mJ/15 Hz, 5.65 J/cm(2); and Group 4, Er:YAG 100 mJ/15 Hz, 7.53 J/cm(2). Five cavities from each group were evaluated by scanning electron microscopy (SEM). The 15 remaining cavities from each group were restored with self-etch adhesive and nano-hybrid composite. After thermocycling, all sample teeth were immersed in 0.2% methylene blue dye and sectioned buccolingually. Statistics were analyzed using the one way ANOVA and Mann-Whitney U tests with Bonferroni correction.

RESULTS

The morphology showed micro-irregularities in the cementum surface of the laser group with the absence of a smear layer. The microstructure characteristics were increased surface roughness followed by increasing laser energy transmission. The Er:YAG laser groups were statistically significant, with less microleakage than the diamond bur group (p<0.05). There was statistically significant difference between the occlusal and gingival microleakage in all the groups (p<0.05). When the laser groups were compared, the lowest microleakage was achieved with energy density at 3.77 J/cm(2) on the occlusal and gingival cementum margin, which showed less microleakage than at energy densities of 5.65 and 7.53 J/cm(2) with Er:YAG laser.

CONCLUSIONS

These observations indicate that the micro-irregularities of the cementum surface could facilitate the formation of a hybridization zone with a self-etch adhesive system. Therefore, the microleakage of Er:YAG laser irradiation was significantly decreased compared with diamond bur cavities.

Evaluation of the clinical success of class I cavities prepared by an Er:YAG laser-5-year follow-up study

The purpose of this study was to evaluate, after 5 years, the clinical success of preparing class 1 composite resin restorations with an Er:YAG laser. Sixty-five teeth of 30 patients were included in the study, and an Er:YAG laser emitting at a wavelength of 2.94 μm was used for the class I cavity preparations with not more than one third of the mesiodistal width of the occlusal surfaces of each tooth. All cavities were restored with a light-cured composite resin, following a single bond application. After the baseline examination, restorations were reevaluated by the same experienced clinician after 5 years, using the modified Ryge criteria. At the end of 5 years, 41 of the 65 restorations were evaluated in 22 patients and scored. With respect to marginal discoloration, anatomic form, color match, and surface texture, significant differences were found between baselines tested after 5 years. Clinical evaluation of postoperative sensitivity showed that 90.2 % were rated as alpha. All restorations evaluated in this study demonstrated acceptable clinical performance within the evaluation period based on the alpha and bravo ratings for clinically satisfactory restorations. Further evaluations are necessary for a better clinical performance analysis.

Reduction of thermocoagulative injury via use of a picosecond infrared laser (PIRL) in laryngeal tissues

The carbon dioxide (CO2) laser is routinely used in glottic microsurgery for the treatment of benign and malignant disease, despite significant collateral thermal damage secondary to photothermal vaporization without thermal confinement. Subsequent tissue response to thermal injury involves excess collagen deposition resulting in scarring and functional impairment. To minimize collateral thermal injury, short-pulse laser systems such as the microsecond pulsed erbium:yttrium-aluminium-garnet (Er:YAG) laser and picosecond infrared laser (PIRL) have been developed. This study compares incisions made in ex vivo human laryngeal tissues by CO2 and Er:YAG lasers versus PIRL using light microscopy, environmental scanning electron microscopy (ESEM), and infrared thermography (IRT). In comparison to the CO2 and Er:YAG lasers, PIRL incisions showed significantly decreased mean epithelial (59.70 µm) and subepithelial (22.15 µm) damage zones (p < 0.05). Cutting gaps were significantly narrower for PIRL (133.70 µm) compared to Er:YAG and CO2 lasers (p < 0.05), which were more than 5 times larger. ESEM revealed intact collagen fibers along PIRL cutting edges without obvious carbonization, in comparison to diffuse carbonization and tissue melting seen for CO2 and Er:YAG laser incisions. IRT demonstrated median temperature rise of 4.1 K in PIRL vocal fold incisions, significantly less than for Er:YAG laser cuts (171.85 K; p < 0.001). This study has shown increased cutting precision and reduced lateral thermal damage zones for PIRL ablation in comparison to conventional CO2 and Er:YAG lasers in human glottis and supraglottic tissues.

The effect of an erbium, chromium: yttrium-scandium-gallium-garnet laser on the microleakage and bond strength of silorane and micro-hybrid composite restorations

Objective:

The aim of this in vitro study was to compare the microleakage and bond strength of Class V silorane-based and universal micro-hybrid composite restorations prepared either with diamond bur or with an erbium, chromium: yttrium-scandium-gallium-garnet (Er, Cr:YSGG) laser.

Materials and Methods:

A total of 160 molar teeth were used for microleakage assessment and shear bond strength (SBS) test. The specimens were prepared using either diamond bur or 3 W-, 4 W- and 5 W-20 Hz Er, Cr:YSGG laser irradiation. All specimens were subjected to thermocycling (500 times at 5 ± 2°C to 55 ± 2°C, dwell time 15 s and transfer time 10 s). Microleakage was assessed using a 0.5% basic-fuchsin solution. The bond strengths were determined using a microtensile tester at a crosshead speed of 0.5 mm/min. The Kruskal Wallis test was used for the analysis of microleakage and a one-way analysis of variance test was used to analyze the SBS (P < 0.05).

Results:

No statistically significant differences were found (P > 0.05) between Er, Cr:YSGG laser and bur preparation methods regarding microleakage and bond strength values.

Conclusion:

Irradiation with Er, Cr:YSGG laser was confirmed to be as effective as conventional methods for preparing cavities before adhesive restorations.

Microleakage in Class V cavities with self-etching adhesive system and conventional rotatory or laser Er,Cr:YSGG

OBJECTIVE

To analyse microleakage in Class V cavity preparation with Er;Cr:YSGG at different parameters using a self-etching adhesive system.

BACKGROUND

Several studies reported microleakage around composite restorations when cavity preparation is done or treated by Er;Cr:YSGG laser. We want to compare different energy densities in order to obtain the best parameters, when using a self-etching adhesive system.

METHODS

A class V preparations was performed in 120 samples of human teeth were divided in 3 groups: (1) Preparation using the burr. (2) Er;Cr:YSGG laser preparation with high energy 4W, 30 Hz, 50% Water 50% Air and (3) Er;Cr:YSGG laser preparation lower energy 1.5 W, 30 Hz, 30% Water 30% Air. All the samples were restored with self-etching adhesive system and hybrid composite. Thermocycling (5000 cycles) and immersed in 0.5% fuchsin. The restorations were sectioned and evaluated the microleakage with a stereomicroscope.

RESULTS

Lower energy laser used for preparation showed significant differences in enamel and dentin. To group 3, the microleakage in the enamel was less, whilst the group 1, treated with the turbine, showed less microleakage at dentin level. Group 2 showed the highest microleakage at dentin/cement level.

CONCLUSION

Burr preparation gives the lowest microleakage at cement/dentin level, whilst Er;Cr:YSGG laser at lower power has the low energy obtains lowest microleakage at enamel. On the contrary high-energy settings produce inferior results in terms of microleakage.

Effects of Er:YAG laser on bond strength of self-etching adhesives to caries-affected dentin

The erbium:yttrium-aluminum-garnet (Er:YAG) laser may be effective the bond strength of adhesive systems on dentine surfaces, the chemical composition and aggressiveness of adhesive systems in clinical practice. The purpose of this study was to evaluate the effects of the Er:YAG laser system with the bonding ability of two different self-etching adhesives to caries-affected dentine in primary molars. Ninety mid-coronal flat dentine surfaces obtained from sound and caries-affected human primary dentine were treated with an Er:YAG laser or a bur. The prepared surfaces were restored with an adhesive system (Xeno V; Clearfil S³) and a compomer (Dyract Extra). The restored teeth were sectioned with a low-speed saw and 162 samples were obtained. The bond strength of the adhesive systems was tested using the micro-tensile test method. The data were statistically analyzed. A restored tooth in each group was processed for scanning electron microscopy evaluation. The values of the highest bond strength were obtained from the Clearfil S³-Er:YAG laser-sound dentine group in all groups. (24.57 ± 7.27 MPa) (P > 0.05). The values of the lowest bond strength were obtained from the Xeno V-Er:YAG laser-sound dentine group in all groups (11.01 ± 3.89 MPa). It was determined that the Clearfil S³ increased the bond strength on the surface applied with Er:YAG laser according to the Xeno V.

Role of surface tension and roughness on the wettability of Er:YAG laser irradiated dentin: In vitro study

INTRODUCTION

The aim of this "in vitro" study was to evaluate the role of surface tension and surface roughness in the wettability, considered essential for a good adhesion, comparing Er:YAG laser - to bur-prepared dentin.

MATERIALS AND METHODS

Dentin surfaces of third human molars were Er:YAG laser- and bur-prepared to evaluate the effects of surface tension and roughness on wettability and interferometric analysis was used to compare the roughness of the two groups surfaces, after gold-coating them.

RESULTS

In bur-prepared samples the time taken for the water drop to spread out was approximately the same with or without metallization while, in the Er:YAG laser-prepared surfaces the spreading-out time was less than 10 seconds but longer after metallization i.e. nearly two minutes. Large differences in wettability measurements were observed because the water drop was almost immediately absorbed on the Er:YAG laser-prepared surface. The wettability test demonstrated that the porous and hydrophilic properties of Er:YAG laser-prepared surfaces are higher than bur-prepared surfaces.

CONCLUSION

Surface tension, surface morphology and porosity had different effects on the spreading time of a water drop on both Er:YAG laser- and bur-prepared surfaces. And, while surface tension does not seem to influence the results, roughness appears to be the main parameter involved in water drop spreading, this being an indication, by the clinical point of view, to the choice of Er:YAG laser parameters in conservative dentistry.

Shear bond strength and ultrastructural interface analysis of different adhesive systems to Er:YAG laser-prepared dentin

The aim of this study was to evaluate the shear bond strength (SBS) of a microhybrid composite resin bonded with three different adhesive systems to Er:YAG laser- (EL) or bur-prepared dentin surfaces and to analyze the quality and ultrastructure of the adhesive-dentin interfaces by scanning electron microscopy (SEM). The specimens prepared for SBS test and SEM analysis were randomly assigned to eight groups (G1-G8): G1, EL (Fidelis PlusIII, Fotona) + Clearfil S3 Bond (C3S); G2, EL + AdperSE Plus (SE); G3, EL + laser etch + Adper Single Bond2 (SB2); G4, EL + acid etch + SB2; G5, EL + SB2 (no etching); G6, bur + acid etch + SB2; G7, bur + S3; G8, bur + SE. Laser was used in very short pulse mode at a setting of 200 mJ/20 Hz for dentin preparation and at 80 mJ/10 Hz for dentin etching. Bond strength test: 3.5 × 2.0 mm cylindrical molds were placed onto adhesives and filled with the composites. After 24 h in distilled water, SBS was tested at a crosshead speed of 0.5 mm/min. SEM analysis: The dentin-adhesive interfaces were evaluated for the ultrastructure of hybrid layer. Data of SBS (MPa) were statistically analyzed by ANOVA and Tukey HSD. ER:YAG laser-prepared dentin has demonstrated significantly more SBS (p < 0.01) for SE when compared to bur-prepared dentin. No significancies (p > 0.05) in SBS have been determined between the total-etch adhesive applied groups with regard to etching types. SEM analysis revealed that hybrid layers obtained in Er:YAG laser-irradiated dentin exhibited more irregular and non-homogeneous pattern than the conventionally prepared dentin. In conclusion, SE Bond demonstrated superior results in Er:YAG laser-ablated dentin compared to bur-prepared dentin.

Shear Bond Strength of an Etch-and-rinse Adhesive to Er:YAG Laser- and/or Phosphoric Acid-treated Dentin

Background and aims. Er:YAG laser irradiation has been claimed to improve the adhesive properties of dentin; therefore, it has been proposed as an alternative to acid etching. The aim of this in vitro study was to investigate the shear bond strength of an etch-and-rinse adhesive system to dentin surfaces following Er:YAG laser and/or phosphoric acid etching. Materials and methods. The roots of 75 sound maxillary premolars were sectioned below the CEJ and the crowns were embedded in auto-polymerizing acrylic resin with the buccal surfaces facing up. The buccal surfaces were ground using a diamond bur and polished until the dentin was exposed; the samples were randomly divided into five groups (n=15) according to the surface treatment: (1) acid etching; (2) laser etching; (3) laser etching followed by acid etching; (4) acid etching followed by laser etching and (5) no acid etching and no laser etching (control group). Composite resin rods (Point 4, Kerr Co) were bonded to treated dentin surfaces with an etch-and-rise adhesive system (Optibond FL, Kerr Co) and light-cured.After storage for two weeks at 37°C and 100% humidity and then thermocycling, bond strength was measured with a Zwick Universal Testing Machine at a crosshead speed of 1 mm/min. Data was analyzed using parametric and non-parametric tests (P<0.05). Results. Mean shear bond strength for acid etching (20.1±1.8 MPa) and acid+laser (15.6±3.5 MPa) groups were significantly higher than those for laser+acid (15.6±3.5 MPa), laser etching (14.1±3.4 MPa) and control (8.1±2.1 MPa) groups. However, there were no significant differences between acid etching and acid+laser groups, and between laser+acid and laser groups. Conclusion. When the cavity is prepared by bur, it is not necessary to etch the dentin surface by Er:YAG laser following acid etching and acid etching after laser etching.

Use of laser in orthodontics: applications and perspectives

Laser technology got in these years a more and more important role in modern dentistry and, recently, also in orthodontics was proposed the utilization of laser devices. The aim of this work is to describe the utilization of this technology both in soft and hard oral tissues to improve orthodontic treatment. Several cases, with different wavelengths (532, 810, 980, 1064, 2940 and 10600 nm) and in different times of the treatment (before, during and after) are presented. All the cases reported showed, according to the literature, that the use of the laser related to orthodontic treatment offers several advantages when compared with conventional methods. In the soft tissues surgery it allows to reduce or eliminate the use of anesthetic injection, to avoid use of sutures and to bond bracket in dry enamel; associated with orthophosphoric acid, it gives a stronger adhesion of the brackets to the enamel and, in the case of porcelain brackets, it detaches them without damages; at low power (LLLT) it permits to control the pain of the first period after bonding and, by increasing the speed of teeth movement in the bone, reduces the time of the treatment.

Use of laser in orthodontics: applications and perspectives

Laser technology got in these years a more and more important role in modern dentistry and, recently, also in orthodontics was proposed the utilization of laser devices. The aim of this work is to describe the utilization of this technology both in soft and hard oral tissues to improve orthodontic treatment. Several cases, with different wavelengths (532, 810, 980, 1064, 2940 and 10600 nm) and in different times of the treatment (before, during and after) are presented. All the cases reported showed, according to the literature, that the use of the laser related to orthodontic treatment offers several advantages when compared with conventional methods. In the soft tissues surgery it allows to reduce or eliminate the use of anesthetic injection, to avoid use of sutures and to bond bracket in dry enamel; associated with orthophosphoric acid, it gives a stronger adhesion of the brackets to the enamel and, in the case of porcelain brackets, it detaches them without damages; at low power (LLLT) it permits to control the pain of the first period after bonding and, by increasing the speed of teeth movement in the bone, reduces the time of the treatment.

The influence of the energy density and other clinical parameters on bond strength of Er:YAG-conditioned dentin compared to conventional dentin adhesion

The aim of this in vitro study was to optimise clinical parameters and the energy density of Er:YAG laser-conditioned dentin for class V fillings. Shear tests in three test series were conducted with 24 freshly extracted human third molars as samples for each series. For every sample, two orofacial and two approximal dentin surfaces were prepared. The study design included different laser energies, a thin vs a thick bond layer, the influence of adhesives as well as one-time- vs two-time treatment. The best results with Er:YAG-conditioned dentin were obtained with fluences just above the ablation threshold (5.3 J/cm(2)) in combination with a self-etch adhesive, a thin bond layer and when bond and composite were two-time cured. Dentin conditioned this way reached an averaged bond strength of 23.32 MPa (SD 5.3) and 24.37 MPa (SD 6.06) for two independent test surfaces while showing no statistical significance to conventional dentin adhesion and two-time treatment with averaged bond strength of 24.93 MPa (SD 11.51). Significant reduction of bond strength with Er:YAG-conditioned dentin was obtained when using either a thick bond layer, twice the laser energy (fluence 10.6 J/cm(2)) or with no dentin adhesive. The discussion showed clearly that in altered (sclerotic) dentin, e.g. for class V fillings of elderly patients, bond strengths in conventional dentin adhesion are constantly reduced due to the change of the responsibles, bond giving dentin structures, whereas for Er:YAG-conditioned dentin, the only way to get an optimal microretentive bond pattern is a laser fluence just above the ablation threshold of sclerotic dentin.

Adhesion to Er:YAG laser and bur prepared root and crown dentine

BACKGROUND

The purpose of this study was to evaluate the bond strengths between dentine and resin composite obtained after Er:YAG laser treatment of crown or root dentine used together with self-etch and total-etch adhesive systems.

METHODS

One etch-and-rinse adhesive (Single Bond, 3M, USA) and one self-etch system (Clearfil SE Bond, Kuraray, Japan) were applied to root and crown dentine prepared with a regular bur in a turbine or with an Er:YAG laser. The shear bond strength was determined after thermocycling and statistically analysed using independent t-tests.

RESULTS

Crown sites bonded using Clearfil SE Bond and Single Bond adhesives yielded bond strengths similar to that of root dentine sites (p > 0.05). Clearfil SE Bond was stronger in both the lased and non-lased groups (p < 0.05). The lowest bond strength was obtained when Single Bond without acid etching was used on Er:YAG ablated dentine. When total-etch adhesive was used, there were significant differences (p < 0.05) between the laser-ablated and laser-ablated/acid-etched and bur-cut/acid-etched groups.

CONCLUSIONS

Er:YAG laser irradiation of root and crown dentine conducted prior to the adhesive protocol adversely affected adhesion and decreased bond strength compared with traditional preparation.

Thermal alteration and morphological changes of sound and demineralized primary dentin after Er:YAG laser ablation

The purpose of this study was to assess the influence of Er:YAG laser pulse repetition rate on the thermal alterations occurring during laser ablation of sound and demineralized primary dentin. The morphological changes at the lased areas were examined by scanning electronic microscopy (SEM). To this end, 60 fragments of 30 sound primary molars were selected and randomly assigned to two groups (n = 30); namely A sound dentin (control) and B demineralized dentin. Each group was divided into three subgroups (n = 10) according to the employed laser frequencies: I-4 Hz; II-6 Hz, and III-10 Hz. Specimens in group B were submitted to a pH-cycling regimen for 21 consecutive days. The irradiation was performed with a 250 mJ pulse energy in the noncontact and focused mode, in the presence of a fine water mist at 1.5 mL/min, for 15 s. The measured temperature was recorded by type K thermocouples adapted to the dentin wall relative to the pulp chamber. Three samples of each group were analyzed by SEM. The data were submitted to the nonparametric Kruskal-Wallis test and to qualitative SEM analysis. The results revealed that the temperature increase did not promote any damage to the dental structure. Data analysis demonstrated that in group A, there was a statistically significant difference among all the subgroups and the temperature rise was directly proportional to the increase in frequency. In group B, there was no difference between subgroup I and II in terms of temperature. The superficial dentin observed by SEM displayed irregularities that augmented with rising frequency, both in sound and demineralized tissues. In conclusion, temperature rise and morphological alterations are directly related to frequency increment in both demineralized and sound dentin.

Application of laser technology for removal of caries: a systematic review of controlled clinical trials

OBJECTIVE

To evaluate the scientific evidence regarding laser technology for removal of carious tissue.

MATERIAL AND METHODS

A search for literature on the effect of treatment and on economic aspects of laser technology identified 23 papers. No relevant studies on economic aspects were found. Regarding the effect of treatment, 16 papers were selected for assessment according to established criteria.

RESULTS

Cavity preparation and caries excavation by erbium laser were evaluated in three studies of medium quality. The time required to remove carious tissue was evaluated in five studies assessed as being of medium quality for this outcome. In four studies the effect of laser treatment on the dental pulp was included as an outcome but, due to the short follow-up time, the quality was assessed as low. Two studies that included the longevity of the restoration as an outcome were also assessed as being of low quality because the follow-up time was inadequate. Patient response was evaluated in three studies, which were assessed as being of medium quality with respect to this outcome.

CONCLUSIONS

There is limited scientific evidence that laser treatment is as effective as a rotary bur for removing carious tissue. Treatment time is prolonged. There is limited scientific evidence that adults prefer laser treatment. No conclusions can be drawn regarding biological or technical complications, children's perception of laser treatment or the cost-effectiveness of the method.

Comparison of the Er,Cr:YSGG laser with a chemical vapour deposition bur and conventional techniques for cavity preparation: a microleakage study

The aim of this study was to compare the effects of the Er,Cr:YSGG laser using chemical vapour deposition (CVD) bur cavity preparation with conventional preparation methods including a diamond bur and a carbide bur on the microleakage with two different adhesive systems. A total of 40 extracted human premolars were randomly assigned to four experimental groups according to the cavity preparation technique: group I diamond bur (Diatech); group II carbide bur (Diatech); group III Er,Cr:YSGG laser (Biolase Millennium II); and group IV CVD bur (CVDentUS). Using the different preparation techniques, Class V standardized preparations were performed on the buccal and lingual surfaces with gingival margins on the dentin and occlusal margins on the enamel. Each preparation group was randomly assigned to two subgroups (five teeth, ten preparations) according to the type of adhesive: an etch-and-rinse adhesive (Adper Single Bond), and a single-step self-etch adhesive (AdheSE One). All preparations were restored with a nanohybrid composite resin in a single increment. Following thermocycling (×500; 5-55°C), the teeth were immersed in basic fuchsin and sectioned in the orovestibular direction. Dye penetration was evaluated under a light microscope by two blinded examiners. Data were statistically analysed with the Kruskal-Wallis and Wilcoxon tests (p<0.05). There were no statistically significant differences between the preparation techniques with either of the two adhesive systems (p>0.05). Comparing the enamel and dentin leakage scores within each group, no statistically significant differences were found (p>0.05). The Er,Cr:YSGG laser cavity preparation did not differ from preparation with CVD, diamond or carbide bur in terms of microleakage with the different adhesive systems.

Direct comparison of the bond strength results of the different test methods: a critical literature review

OBJECTIVE

The goal of this paper is to undertake a literature search collecting all dentin bond strength data obtained for six adhesives with four tests (shear, microshear, tensile and microtensile) and to critically analyze the results with respect to average bond strength, coefficient of variation, mode of failure and product ranking.

METHOD

A PubMed search was carried out for the years between 1998 and 2009 identifying publications on bond strength measurements of resin composite to dentin using four tests: shear, tensile, microshear and microtensile. The six adhesive resins were selected covering three step systems (OptiBond FL, Scotch Bond Multi-Purpose Plus), two-step (Prime & Bond NT, Single Bond, Clearfil SE Bond) and one step (Adper Prompt L Pop).

RESULTS

Pooling results from 147 references showed an ongoing high scatter in the bond strength data regardless which adhesive and which bond test was used. Coefficients of variation remained high (20-50%) even with the microbond test. The reported modes of failure for all tests still included high number of cohesive failures. The ranking seemed to be dependant on the test used.

SIGNIFICANCE

The scatter in dentin bond strength data remains regardless which test is used confirming Finite Element Analysis predicting non-uniform stress distributions due to a number of geometrical, loading, material properties and specimens preparation variables. This reopens the question whether, an interfacial fracture mechanics approach to analyze the dentin-adhesive bond is not more appropriate for obtaining better agreement among dentin bond related papers.