Clinical dental application of Er:YAG laser for Class V cavity preparation

Patient and Clinician Experiences When Using a CO2 Laser for Cavity Preparations: Lessons learned from Prospective Clinical Research

This prospective clinical study evaluated the experiences and preferences of both patients and clinicians when performing class I–V cavity preparation procedures using a 9300 nm CO2 laser without anesthetic. A total of 233 procedures were performed on 103 patients. Following treatment, patients were asked to describe discomfort/pain levels and preferences for future treatment with either laser treatment or traditional therapy. Additionally, clinicians were asked to rate their experiences with the procedures in three technical domains: speed, ease-of-use, and precision. In total, 98% of patients preferred laser treatment to traditional therapy and 93% of all procedures performed were completed with no anesthesia. Younger patients and patients receiving multiple restorations reported significantly higher discomfort, though discomfort scores were very low overall (below 3 on a 10-point pain scale). While there were significant differences in clinician experiences, each clinician reported having generally high satisfaction using the laser with respect to speed, ease of use, and precision. In conclusion, the 9300 nm CO2 laser provides clinicians a viable option for cavity preparations in dentistry as evidenced by high rates of anesthesia-free procedures with low reported discomfort, the fact that nearly all patients would opt for laser use on future cavity preparations, and generally positive experiences reported by clinicians.

Laser Analgesia Associated with Restorative Dental Care: A Systematic Review of the Rationale, Techniques, and Energy Dose Considerations

It is a common experience amongst laser dentists and patients that mid-IR wavelength application in cavity preparation may be achieved without causing any associated pain. The erbium family of lasers (Er,Cr:YSGG 2780 nm and Er:YAG 2940 nm) are frequently used without employing injectable local anesthesia as an adjunct: the phenomenon arising from the application of these devices is known as laser analgesia. This review seeks to apply a systematic approach to the examination of appropriate published studies but also to highlight the need for much more structured clinical investigations that consolidate photonic dose and methodology. A search of published data using PRISMA criteria was carried out to examine clinical trials into laser analgesia in conjunction with restorative dentistry, applying inclusion and exclusion criteria. From this, 10 published articles were selected for analysis. Suitability assessment was carried out, using a modified Cochrane risk of bias methodology. In 8/10 of the included studies, laser-induced analgesia is claimed to be better and effective, while in 2/10 of the studies, no difference was exhibited compared to the control group. Statistical analysis of three split mouth studies concluded that only one of these investigations reviewed demonstrated a significant analgesic effect for laser treatment while the other two did not support this observation. From this data, it is inconclusive to assess the predictability of laser analgesia in cavity preparation. A possible rationale and laser operating parametry has been discussed. Successful implementation of this treatment modality remains technique sensitive and subject to further investigation.

Four-year clinical prospective follow-up of resin composite restoration after selective caries removal using Er:YAG laser

OBJECTIVES

The aim of this study was to longitudinally evaluate, after a 4-year period, the clinical longevity of composite resin restoration compared to the baseline, after selective caries removal in permanent molars using Er:YAG laser or bur preparation with biomodification of dentin with the use of chlorhexidine.

METHODS

Selective caries removal was performed on 80 teeth of 20 individuals who each had at least four active carious lesions. These lesions, located on occlusal surfaces of permanent molar counterparts, were removed using (i) Er:YAG laser biomodified with chlorhexidine, (ii) Er:YAG laser and application of deionized water, (iii) bur preparation biomodified with chlorhexidine, and (iv) bur preparation and application of deionized water. At the end of 4 years, 64 of the 80 restorations were evaluated in 16 individuals (n = 16). The restorations were evaluated, both clinically and photographically, using scanning electron microscopy (SEM) and pulp vitality analysis. The experimental data were statistically evaluated by kappa, Fisher's, and chi-square tests, with a significance level of 5%. The Kaplan-Meier test and the Cox regression analysis were used to evaluate the survival of the restorations.

RESULTS

After 4 years of follow-up, there was a statistically significant difference in marginal discoloration criteria for all of the groups evaluated. For marginal adaptation criteria, there was a statistically significant difference for the Er:YAG laser group biomodified with chlorhexine (p = 0.050). For clinical and radiographic evaluation of pulp vitality, there were no statistically significant differences among the groups (p = 0.806).

CONCLUSION

Er:YAG laser can be used for selective caries removal, regardless of dentin biomodification with chlorhexidine or application of deionized water, once it produced promising results in composite resin restorations after 4 years of follow-up, according to the criteria evaluated. The selective caries removal using Er:YAG laser or bur and the biomodification of dentin with the use of chlorhexidine did not influence the survival of composite resin restorations after the 4-year follow-up period.

CLINICAL RELEVANCE

Composite resin restorations applied after selective caries removal using Er:YAG laser or burs, regardless of dentin biomodification with the use of chlorhexidine or application of deionized water, showed adequate clinical behavior after 4 years of follow-up.

Influence of Surface Treatment on Composite Adhesion in Noncarious Cervical Lesions: Systematic Review and Meta-analysis

The purpose of this study was to analyze the influence of dentin surface treatments on the retention rate of resin composite restorations in non-carious cervical lesions (NCCLs). Seven randomized clinical trials were included in this review. Data regarding retention rate, type of surface treatment, and the main characteristics of studies were analyzed. Two reviewers performed a literature search up to December 2016 in eight databases: PubMed (Medline), Lilacs, Ibecs, Web of Science, BBO, Scopus, Scielo and The Cochrane Library. Only clinical trials evaluating dentin surface treatments in resin composite restoration in NCCLs were included. Noncontrolled clinical trials, reviews, editorial letters, case reports, case series and studies published in a language other than English, Portuguese, or Spanish were not included. The included studies evaluated different surface treatments, such as using an adhesive system with a frictional technique, drying the dentin, and removing sclerotic dentin by using a bur and applying EDTA before primer use. The analysis considering the mechanical removal of dentin surface with a bur and the application of an adhesive system in a frictional mode showed these treatments improved retention rates of the resin composite restorations in NCCLs ( p<0.05). There is evidence in the literature suggesting that the mechanical removal of dentin surface with a bur and the application of an adhesive system in a frictional mode could improve the retention rates of resin composite restorations in NCCLs. However, the studies showed high heterogeneity, and additional clinical trials are needed to determine the best dentin treatment option in NCCLs.

Bonding to Er-YAG-laser-treated Dentin

Er-YAG laser irradiation has been claimed to improve the adhesive properties of dentin. We tested the hypothesis that dentin adhesion is affected by Er-YAG laser conditioning. Superficial or deep dentin from human molars was: (a) acid-etched with 35% H3PO4; (b) irradiated with an Er-YAG laser (KaVo) at 2 Hz and 180 mJ, with water-cooling; and (c) laser- and acid-etched. Single Bond (3M ESPE) and Z100 composite (3M ESPE) were bonded to the prepared surfaces. After storage, specimens were tested in shear to failure. Bonded interfaces were demineralized in EDTA and processed for transmission electron microscopy. Two-way ANOVA revealed that conditioning treatment and interaction between treatment and dentin depth significantly influenced shear bond strength results. Acid-etching alone yielded shear bond strength values that were significantly higher than those achieved with laser ablation alone, or in combination with acid-etching. The Er-YAG laser created a laser-modified layer that adversely affects adhesion to dentin, so it does not constitute an alternative bonding strategy to conventional acid etching.

Achieving Dental Analgesia with the Erbium Chromium Yttrium Scandium Gallium Garnet Laser (2780 nm): A Protocol for Painless Conservative Treatment

OBJECTIVE

The aim of this research is to evaluate those techniques and optimal parameters of Erbium Chromium Yttrium Scandium Gallium Garnet (Er,Cr:YSGG) laser use in delivering predictable painless (or with very limited discomfort) restorative cavity preparation without the aid of injected local anesthesia.

MATERIAL AND METHODS

This study was conducted on 30 patients (26 adults and 4 youth 9-16 years old; average age, 37) treated in a private practice. For each patient, a single cavity was prepared using the Er,Cr:YSGG laser (2780 nm). An Electric Pulp Tester (EPT) was used to monitor the changes in pulp sensibility threshold. The patient experience was tested before and after the treatment using a modified Visual Analogue Scale (VAS) and Children's Fear Survey Schedule-Dental Subscale (CFSS-DS) to evaluate pain and anxiety.

RESULTS

Pain analysis indicated that 80% of patients (24 out of 30) felt no pain and no discomfort, or only a very slight sensation. None of the 30 patients requested anesthesia. EPT was found to be unreliable in evaluating pulpal pain threshold levels. A tendency was noted wherein greater discomfort was felt by anxious patients. On average, the older the patient, the less discomfort was felt. The factors that have a greater tendency to promote discomfort were: posterior teeth, greater caries depth, greater use of higher power levels and ablation time.

CONCLUSIONS

Using the Er,Cr:YSGG laser, it was possible to avoid local anesthesia during cavity preparation with a bur. The treatment was effective in a high number of cases (80%), leading to reduction in the anxiety frequently associated with dental care.

Clinical evaluation of composite restorations in Er:YAG laser-prepared cavities re-wetting with chlorhexidine

OBJECTIVES

The objective of this study was to evaluate longitudinally the composite restorations, performed in cavities prepared by Er:YAG or conventional bur, and dentin re-wetting with water or chlorhexidine.

MATERIALS AND METHODS

Twenty individuals with four active caries with cavitation reaching the dentin located on the occlusal surface of molars counterparts are selected. The teeth of each individual were randomly assigned into four groups: (I) Er:YAG laser (260 mJ/4 Hz) re-wetting with chlorhexidine, (II) Er:YAG laser (260 mJ/4 Hz) re-wetting with deionized water, (III) conventional method re-wetting with chlorhexidine, and (IV) conventional method re-wetting with deionized water. The teeth were isolated, prepared cavities, phosphoric acid etching, and re-wetting according to previously assigned method. Restoration was performed employing the Single Bond 2 and Z350XT resin. Clinical follow-up was held after the polishing of the restoration (baseline) and 6 and 12 months of the making of the restoration using the modified USPHS criteria. The restorations were qualitatively analyzed by means of photographs. In the evaluation period, replicas of the restorations were analyzed by SEM. Data were analyzed by statistics using chi-square test (p < 0.05).

RESULTS

After 12 months of clinical evaluation, groups prepared with laser and re-wetting with chlorhexidine and water showed the lowest marginal staining value. There was no statistical difference between the groups for other factors. SEM analysis revealed that a non-expressive amount of restorations showed gaps and irregularities of tooth-restoration interface after 6 and 12 months compared to the baseline.

CONCLUSION

The restorations performed in laser-prepared cavities, regardless of the re-wetting, presented the best clinical performance over the evaluated period.

CLINICAL RELEVANCE

Laser-prepared teeth, regardless of re-wetting, showed greater resistance to marginal discoloration.

Assessing microleakage of composite restorations in class V cavities prepared by Er:YAG laser irradiation or diamond bur

Introduction:

The aim of this study was to make a comparison between microleakage of conventionally restored class V cavities using bur and acid etchant and, the ones prepared and conditioned by Er:YAG laser.

Materials and Methods:

30 recently extracted intact caries and filling free human permanent molars were used for this study. Then, Cold cure acrylic resin was used to seal the apices. The samples were randomly assigned to 5 groups of six each. Class V cavities were prepared one on buccal and one on lingual surface of each sample. Group 1: cavity preparation by diamond bur and turbine + acid etch, Group 2: cavity preparation by Er:YAG laser + acid etch, Group 3: cavity preparation by Er:YAG laser + Laser etching, Group 4: cavity preparation by diamond bur and turbine + laser etching, Group 5: cavity preparation by Er:YAG laser with no conditioning procedure. The cavities restored with restorative composite resin. Samples were then immersed in 2% methylene blue solution for 24 hours. The data were then analyzed using Wilcoxon signed ranks test and Kruskal-Wallis statistical tests.

Results:

The Kruskal Wallis test showed a significant difference (P < 0.05) between enamel and cementum margin microleakage, while the higher microleakage was related to the cementum margin of restorations.

Conclusion:

There was no significant difference in evaluating microleakeage degree of cavities prepared by Er:YAG laser and diamond bur.

Long-term chlorhexidine effect on bond strength to Er:YAG laser irradiated-dentin

This study evaluates the bond strength of dentin prepared with Er:YAG laser or bur, after rewetting with chlorhexidine on long-term artificial saliva storage and thermocycling. One hundred and twenty human third molars were sectioned in order to expose the dentin surface (n = 10). The specimens were randomly divided in 12 groups according to treatment and aging: Er:YAG laser rewetting with deionized water (LW) and 24 h storage in artificial saliva (WC); LW and 6 months of artificial saliva storage + 12.000 thermocycling (6M), LW and 12 months of artificial saliva storage + 24.000 thermocycling (12M), Er:YAG laser rewetting with 2% chlorhexidine (LC) and WC, LC and 6M, LC and 12M, bur on high-speed turbine rewetting with deionized water (TW) and WC, TW6M, TW12M, bur on high-speed turbine + 2% chlorhexidine (TC) and WC, TC and 6M, TC and 12M. The specimens were etched with 35% phosphoric acid, washed, and dried with air. Single Bond 2 adhesive was applied and the samples were restored with a composite. Each tooth was sectioned in order to obtain 4 sticks, which were submitted to microtensile bond strength test (µTBS). The two-way ANOVA, showed no significant differences for the interaction between the factors and for the aging factor. Tukey 5% showed that the LC group had the lowest µTBS. The rewetting with chlorhexidine negatively influenced the bond strength of the preparation with the Er:YAG laser. The artificial saliva aging and thermocycling did not interfere with dentin bond strength.

Er:YAG laser or high-speed bur for cavity preparation in adolescents

OBJECTIVES

The aim was to evaluate the effect on cavity preparation time, the pulse changes and the patient's subjective experience during removal of healthy tooth substance with high-speed bur and Er:YAG laser.

MATERIALS AND METHODS

Thirty-five (13 male, 22 female) 14-18-year-olds participated. After local anaesthesia, Er:YAG laser and high-speed diamond bur were used for a 2 mm deep cavity preparation on the middle of the buccal surface on contra-lateral healthy maxillary first premolars. The cavity preparation time and the pulse were measured during the treatment. Subjective experience was evaluated using a VAS-scale and a questionnaire. Wilcoxon Signed Rank test and Chi-2-test were used for statistical analyses.

RESULTS

The mean (SD) cavity preparation time was 3.7-times longer (p < 0.001) for the laser [59 (41) s] than for the high-speed bur [16 (4) s]. The mean pulse change during preparation differed (p < 0.05) between the bur (+2.2%) and laser (-4.4%). The smell was worse when laser was used (p < 0.01); 65.7% expressed less discomfort and 57.1% experienced a lower sound level when laser was used. Laser was preferred for future treatment in 62.9% of the adolescents.

CONCLUSION

Laser ablation caused unpleasant smell and longer cavity preparation time, but was preferred by a majority of the adolescents.

Temperature rises during application of Er:YAG laser under different primary dentin thicknesses

OBJECTIVE

The present study investigated the effects of the Er:YAG laser's different pulse repetition rates on temperature rise under various primary dentin thicknesses.

BACKGROUND DATA

The Er:YAG laser can be used for restorative approaches in clinics and is used to treat dental caries. There are some reports that explain the temperature rise effect of the Er:YAG laser. Recently, the Er:YAG laser has been found to play an important role in temperature rises during the application on dentin.

METHODS

Caries-free primary mandibular molars were prepared to obtain dentin discs with 0.5, 1, 1.5, and 2 mm thicknesses (n=10). These discs were placed between the Teflon mold cylinders of a temperature test apparatus. We preferred three pulse repetition rates of 10, 15, and 20 Hz with an energy density of 12.7 J/cm2 and a 230 μs pulse duration. All dentin discs were irradiated for 30 sec by the Er:YAG laser. Temperature rises were recorded using an L-type thermocouple and universal data loggers/scanners (E-680, Elimko Co., Turkey). Data were analyzed by two-way ANOVA and Tukey tests.

RESULTS

Whereas the lowest temperature rise (0.44±0.09 °C) was measured from a 10 Hz pulse repetition rate at a dentin thickness of 2 mm, the highest temperature rise (3.86±0.43 °C) was measured from a 20 Hz pulse repetition rate at a 0.5 mm dentin thickness.

CONCLUSIONS

Temperature rise did not reach critical value for pulpal injury in any primary dentin thicknesses irradiated by a high repetition rate of the Er:YAG laser.

Removal of organic debris with Er:YAG laser irradiation and microleakage of fissures sealants in vitro

The current study was conducted to improve fissure sealing by pre-treatment with Er:YAG laser irradiation in order to remove organic debris. The surface morphology, surface roughness of fissure cavities, and the degree of microleakage after laser treatment were compared with those after bristle brush treatment in vitro. Sixty extracted human teeth were used in this study. The teeth were randomly divided into two groups of 30 each. Artificial fissures were prepared in all teeth into which artificial organic debris was placed. The debris in 30 teeth of one group was removed by means of Er:YAG laser system and the remaining 30 teeth were cleaned using a bristle brush with prophylaxis paste. Surface morphology and surface roughness of were analyzed in ten samples from each group by color laser three-dimensional (3D) microscopy and by scanning electron microscopic examination. The remaining samples were then filled with sealant and subjected to a microleakage test under thermocycling. Statistical analysis was performed using the Mann-Whitney U test; a value of p < 0.05 was considered significant. Morphologically, most of the debris was removed by Er:YAG laser treatment, whereas some fissures were not cleaned by bristle brush. However, microleakage test of both laser and etched brush methods showed similar results. Laser technique might facilitate good adaptation of resin sealant to enamel, because of an increase in surface roughness and favorable surface characteristics.

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.

Pulpal temperature increase with high-speed handpiece, Er:YAG laser and ultrasound tips

The aim of this study was to compare intrapulpal temperature increase produced by high-speed handpiece, Er:YAG laser and CVDentus ultrasound tips during cavity preparation. Thirty bovine mandibular incisors with an enamel/dentin thickness of 4 mm at buccal surface had their roots amputated and were allocated to the following groups (n=10): Group I- high-speed handpiece; Group II- noncontact Er:YAG laser (250 mJ/4Hz); and Group III- CVDentus ultrasouns tips. All devices were used with water cooling. Class V cavities were prepared to a depth of 3.5 mm, measured with a periodontal probe. A type T thermocouple was placed inside the pulp chamber to determine the temperature increase (°C), which was recorded by a data acquisition system ADS 2000 IP (Lynx Technology) linked to a notebook computer. Data were analyzed statistically by oneway ANOVA and Tukey's test (p=0.05). The mean temperature rises were: 1.10°C (±0.56) for Group I, 0.84°C (±0.55) for Group II, and 3.00°C (± 1.34) for Group III. There were no statistically significant differences (p>0.05) between Groups I and II, but both of them differed significantly from Group III (p<0.05). In conclusion, the use of Er:YAG laser and high-speed handpiece for cavity preparation resulted in similar temperature increase. Although ultrasound tips generated significantly higher intrapulpal temperature increase, it remained below the critical value of 5.5°C and may be considered safe for use.

Effect of erbium:yttrium-aluminum-garnet laser energies on superficial and deep dentin microhardness

This study evaluated the microhardness of superficial and deep dentin irradiated with different erbium:yttrium-aluminum-garnet (Er:YAG) laser energies. Seventy-two molars were bisected and randomly assigned to two groups (superficial dentin or deep dentin) and into six subgroups (160 mJ, 200 mJ, 260 mJ, 300 mJ, 360 mJ, and control). After irradiation, the cavities were longitudinally bisected. Microhardness was measured at six points (20 microm, 40 microm, 60 microm, 80 microm, 100 microm, and 200 microm) under the cavity floor. Data were submitted to analysis of variance (ANOVA) and Fisher's tests (alpha = 0.05). Superficial dentin presented higher microhardness than deep dentin; energy of 160 mJ resulted in the highest microhardness and 360 mJ the lowest one. Values at all points were different, exhibiting increasing microhardness throughout; superficial dentin microhardness was the highest at 20 microm with 160 mJ energy; for deep dentin, microhardness after irradiation at 160 mJ and 200 mJ was similar to that of the control. The lowest energy increased superficial dentin microhardness at the closest extent under the cavity; deep dentin microhardness was not altered by energies of 160 mJ and 200 mJ.

Bond durability in erbium:yttrium-aluminum-garnet laser-irradiated enamel

This study sought to evaluate the influence of thermocycling and water storage on the microtensile bond strength of composite resin bonded to erbium:yttrium-aluminum-garnet (Er:YAG)-irradiated and bur-prepared enamel. Eighty bovine incisors were selected and sectioned. Specimens were ground to produce a flat enamel surface. Samples were randomly assigned according to cavity preparation device: (I) Er:YAG laser and (II) high-speed turbine, and were subsequently restored with composite resin. They were subdivided according to the duration of water storage (WS)/number of thermocycles (TCs): 24 h WS/no TCs; 7 days WS/500 TCs; 1 month WS/2,000 TCs; 6 months WS/12,000 TCs. The teeth were sectioned into 1.0 mm(2)-thick slabs and subjected to tensile stress in a universal testing machine. Data were submitted to two-way analysis of variance (ANOVA) and Tukey's test at a 0.05 significance level. The different periods of water storage and thermocycling did not influence the microtensile bond strength (microTBS) values in the Er:YAG laser-prepared groups. In bur-prepared enamel, the group submitted to 12,000 TCs/6 months' WS (IID) showed a significant decrease in bond strength values when compared to the group stored in water for 24 h and not submitted to thermocycling (IIA), but values were statistically similar to those obtained in all Er:YAG laser groups and in the bur- prepared groups degraded with 500 TCs/1 week WS (IIB) or 2,000 TCs/1 month WS (IIC). It may be concluded that adhesion of an etch-and-rinse adhesive to Er:YAG laser-irradiated enamel was not affected by the methods used to simulate degradation of the adhesive interface and was similar to adhesion in the bur-prepared groups in all periods of water storage and thermocycling.

Clinical evaluation of periodontal surgical treatment with an Er:YAG laser: 5-year results

BACKGROUND

The aim of the present study was to evaluate and compare the long-term clinical outcomes of erbium-doped:yttrium, aluminum, and garnet (Er:YAG) laser-assisted periodontal flap surgery versus conventional treatment with the modified Widman flap procedure.

METHODS

A total of 146 single-rooted periodontally involved teeth from 25 patients were included in this study. In each patient, left or right maxillary single-rooted teeth were assigned randomly to one of two groups: group A (Er:YAG laser) and group B (modified Widman flap surgery). Er:YAG laser was used to debride the bone pockets, scale the root surface, and trim the periodontal flap. Recession, probing depth (PD), clinical attachment level (CAL), plaque index (PI), gingival index (GI), and bleeding on probing (BOP) scores were recorded at baseline and at 3, 6, 12, 24, 36, 48, and 60 months.

RESULTS

Both treatments resulted in decreases in PD, PI, GI, and BOP, increases in gingival recession, and gains in CAL. PD reduction in group A versus group B was statistically significant at 6, 12, 24, and 36 months (P < 0.05). Gains in CAL were significantly greater in group A versus group B at 6, 12, 24, and 36 months. BOP scores were significantly lower in group A versus group B at 3 and 6 months (P < 0.05). All other differences between treatment groups were not statistically significant.

CONCLUSIONS

Surgical treatment of single-rooted teeth with chronic periodontitis using the Er:YAG laser yields greater PD reduction and gains in CAL for up to 3 years compared to conventional Widman flap surgery. The short-term results obtained with both treatments can be maintained over 5 years.

Assessment of Thermal Alteration during Class V Cavity Preparation Using the Er:YAG Laser

OBJECTIVE

The aim of this study was to evaluate in vitro the pulp thermal alterations during class V cavity preparations using the Er:YAG laser and high-speed water flow.

MATERIALS AND METHODS

Forty human teeth were selected and prepared for the thermocouple adaptation in the pulp chamber. The specimens were assigned to four groups: (1) laser 300 mJ/3 Hz, (2) laser 300 mJ/4 Hz, (3) high-speed 9 mL/min water flow, and (4) high-speed 100 mL/min water flow. The temperature was measured before the beginning and at the end of the preparation, as well as during the procedures. The groups were analyzed by scanning electron microscopy.

RESULT

Data analysis disclosed temperature reduction at high-speed drilling with the high-speed total water flow group, and these values were statistically different from the other groups. The results of the 9-mL/min water flow group were similar to those of the 300-mJ/3-Hz group and different from the 300-mJ/4-Hz laser group.

CONCLUSION

The laser promoted a greater increase in temperature only when compared with high-speed handpiece and water flow rate of 100 mL/min.

Surgical lasers and hard dental tissue

The cutting of dental hard tissue during restorative procedures presents considerable demands on the ability to selectively remove diseased carious tissue, obtain outline and retention form and maintain the integrity of supporting tooth tissue without structural weakening. In addition, the requirement to preserve healthy tissue and prevent further breakdown of the restoration places the choice of instrumentation and clinical technique as prime factors for the dental surgeon. The quest for an alternative treatment modality to the conventional dental turbine has been, essentially, patient-driven and has led to the development of various mechanical and chemical devices. The review of the literature has endorsed the beneficial effects of current laser machines. However utopian, there is additional evidence to support the development of ultra-short (nano- and femto-second) pulsed lasers that are stable in use and commercially viable, to deliver more efficient hard tissue ablation with less risk of collateral thermal damage. This paper explores the interaction of laser energy with dental hard tissues and bone and the integration of current laser wavelengths into restorative and surgical dentistry.

Effect of a Novel Er:YAG Laser in Caries Removal and Cavity Preparation: A Clinical Observation

OBJECTIVE

We evaluated the applicability of a novel Er:YAG laser under clinical conditions.

BACKGROUND DATA

The Er:YAG laser has been demonstrated to be a safe and effective alternative to the conventional turbine bur, but the relatively low cutting speed prevented the wide application of Er:YAG laser in clinical cavity preparation.

METHODS

A Smart 2940 D laser developed by Deka Corporation was used for cavity preparation in 95 teeth of 45 patients. Parameters were as follows: wavelength 2.94 microm, pulse energy 700 mJ, repetition rate 8 Hz. Pain, discomfort, assessment during cavity preparation, prognosis factor, and overall clinical evaluation were assessed during or after treatment.

RESULTS

No adverse reaction was observed in any tooth. No intraoperative pain or only slight intraoperative pain was described in 85 teeth (89.5%). Cavity preparation was completed with the laser system alone in 90 teeth (94.7%). Overall clinical evaluation showed no safety problems, with a very good or good rating in 86 teeth (90.5%). The overall operation time was 49 sec on average.

CONCLUSION

The Smart 2940 D is an efficient, effective, safe, and suitable instrument for caries removal and for cavity preparation. It greatly shortens operation time.

Microleakage of resin-based sealants after Er:YAG laser conditioning

The aim of this in vitro study was to investigate the effects of Er:YAG laser pretreatment procedures in fissure sealing. The fissures of 90 third molars were prepared in the mesial halves with Er:YAG laser (lambda = 2,940 nm, 250 mJ/pulse, 4 Hz, fluence 32 J/cm(2)) and acid etched. They were randomly assigned to three groups, and the fissures in the distal halves were prepared differently according to the group: acid etching alone, bur and etching or Er:YAG laser alone. The fissures were sealed using Clinpro sealant (3M). The extent of microleakage was measured with a digital-image analyzer. The sealants prepared with Er:YAG laser alone displayed greater microleakage than the others (p < 0.05). Er:YAG laser irradiation does not eliminate the need for etching the enamel surface before sealing.

Resin adhesion to caries-affected dentine after different removal methods

BACKGROUND

Caries-affected dentine is the common bonding substrate when treating a patient. At present, there are many methods used for caries removal. The aim of this study was to evaluate the microtensile bond strength of two adhesives (Clearfil Protect Bond and OptiBond Solo Plus Total-Etch) to caries-affected dentine after three different caries removal methods.

METHODS

Extracted carious human third molars were used and caries-affected dentine surfaces were obtained from one of the three removal methods: (i) round steel bur in a slow-speed handpiece; (ii) Er:YAG laser; or (iii) 600-grit silicon carbide abrasive paper. Each of the adhesives was used to bond resin composite to the caries-affected dentine according to the manufacturers' instructions. Hourglass-shaped specimens were prepared and stressed in tension at 1mm/min. Data were analysed using two-way analysis of variance and least significant difference test.

RESULTS

Clearfil Protect Bond showed significantly lower bond strength than OptiBond Solo Plus Total-Etch after caries removal with round steel bur, but the opposite was found for specimens treated with silicon carbide abrasive paper. For laser-treated dentine, no significant differences between the adhesives were revealed.

CONCLUSIONS

Besides the differences in adhesives, different caries removal methods seem to influence resin adhesion to caries-affected dentine.

Resin Bonding to Dentin Irradiated by High Repetition Rate Er:YAG Laser

OBJECTIVE

This study evaluated the influence of laser irradiation with a high pulse repetition rate on dentin bonding.

BACKGROUND DATA

Although resin bonding to erbium:yttrium-aluminium-garnet (Er:YAG) laserirradiated dentin has frequently been investigated, the effects of a high pulse repetition rate have not yet been sufficiently investigated.

METHODS

Four groups treated under different laser conditions were evaluated in this study: 100 mJ/pulse-10 pulses per second [pps], 50 mJ/pulse-20 pps, 33 mJ/pulse-30 pps, and the unlased condition as a control. The total energy used to irradiate each group was adjusted to 1.0 W. After bovine dentin specimens were irradiated by an Er:YAG laser, acid conditioners (10% citric acid/3% ferric chloride) were applied to the lased surface. Thereafter, a PMMA rod was bonded to the lased dentin using 4- META/MMA-TBB resin, and mini-dumbbell-shaped specimens were prepared. These specimens were then tested under tensile mode and fractured surfaces were observed under scanning electron microscopy (SEM).

RESULTS

The bond strength of the unlased control was significantly higher than those of the three lased groups. Among the three lased groups, irradiation with higher output energy and lower pulse repetition rate tended to affect the higher bond strength. Upon SEM observation of the fractured surface, the lased groups showed the mixture of failure in the hybrid layer in almost part. There was no significant difference among the three lased groups.

CONCLUSION

It can be concluded from the results of this study that a higher pulse repetition rate is not effective for resin bonding to laser-irradiated dentin.

Influence of Er:YAG Laser on Cavity Preparation and Surface Treatment in Microleakage of Composite Resin Restorations

OBJECTIVE

The purpose of this study was to assess microleakage on class V cavities prepared by Er:YAG laser with varying surface treatment.

BACKGROUND DATA

There has been little reported research on microleakage at cavities prepared and treated with Er:YAG laser.

METHODS

Fifty preparations using Er:YAG laser or a highspeed handpiece were developed. The surface treatment was performed as follows: Er:YAG laser (group 1); 35% phosphoric acid (group 2); laser + acid (group 3); finishing with low-speed + laser + acid (group 4); conventional preparation developed with a high-speed handpiece + acid (group 5--control). The samples were restored with Single Bond/Z250, thermocycled, isolated, and immersed in a 50% AgNO(3) solution. The restorations were sectioned, and the microleakage was measured in milimeters using a specific computer software. Data were analyzed employing ANOVAand Tukey test.

RESULTS

Statistical analysis showed that group 5 (G5) obtained the lowest results of microleakage (22.05%), and it was statistically similar (p > 0.05) to G1 (37.7%) and different (p < 0.05) from the other groups (G2 = 50.4%; G3 = 43%; G4 = 44.2%). The occlusal margins (22.62%) demonstrated less microleakage (p < 0.05) than the cervical margins (56.32%).

CONCLUSION

The use of Er:YAG laser for cavity preparation and surface treatment negatively influenced the marginal sealing of composite resin restorations.

Periodontal tissue healing following flap surgery using an Er:YAG laser in dogs

BACKGROUND AND OBJECTIVES

The purpose of this study was to compare periodontal tissue healing following flap surgery using an Er:YAG laser with that of conventional surgery.

STUDY DESIGN/MATERIALS AND METHODS

Bilateral premolars with experimentally induced periodontitis in six dogs were treated by periodontal flap surgery. Degranulation and root debridement in the furcation were performed using an Er:YAG laser or curet. At 3 months postsurgery, animals were sacrificed and decalcified specimens were prepared for histological and histometric analysis.

RESULTS

Degranulation and root debridement were effectively performed with an Er:YAG laser without major thermal damage and significantly faster than with a curet. Histologically, the amount of newly formed bone was significantly greater in the laser group than in the curet group, although both groups showed similar amounts of cementum formation and connective tissue attachment.

CONCLUSIONS

The Er:YAG laser irradiation can be safely and effectively utilized in periodontal flap surgery, and has the potential to promote new bone formation.

Morphological Study of the Er,Cr:YSGG Laser for Root Canal Preparation in Mandibular Incisors with Curved Root Canals

OBJECTIVE

The objectives of this study were to observe morphological changes of root canal walls and to evaluate the capability of Er,Cr:YSGG laser for preparation of curved mandibular incisor root canals in vitro.

BACKGROUND DATA

There are no published reports on the use of Er,Cr:YSGG laser for curved root canal preparation.

METHODS

Twenty curved mandibular incisor root canals (10 and 15 degrees) were prepared sequentially by laser irradiation at 20 Hz, 2 Wusing two different sizes of fine fiber tips (200 and 320 microm in diameters). After laser irradiation, the teeth were bisected longitudinally, and the specimens were observed by stereoscope and scanning electron microscope (SEM).

RESULTS

Root canal walls of the irradiated areas showed step-like appearances and openings of dentinal tubules, and root canal preparation, having curvatures of less than 10 degrees, could be carried out by this laser irradiation.

CONCLUSIONS

Er,Cr:YSGG laser irradiation is capable of preparing root canals having curvatures of less than 10 degrees.

Shear bond strength and SEM evaluation of composite bonded to Er:YAG laser-prepared dentin and enamel

OBJECTIVES

The purpose of this study was to evaluate dentin and enamel bond strength to resin composite following high-speed rotary or Er:YAG laser preparation using a total etch adhesive system. The microstructure of resin-tooth interfaces was also investigated.

METHODS

Human dentin and enamel specimens were prepared with a high-speed handpiece (KaVo) or Er:YAG laser (DELight) at manufacturer's recommended settings and etched with either 37% H(3)PO(4), laser etched, or not etched. Composite rods (Z-250, 3M/ESPE) were bonded to specimens with an adhesive (Adper Scotchbond Multi-Purpose, 3M/ESPE). After thermocycling, specimens were tested in shear to failure.

RESULTS

Two-factor ANOVA detected significant differences in the main effects of preparation and etch type, and interaction (p<0.001). Post hoc analyses showed that in both dentin and enamel, only the acid-etched specimens had significantly higher mean bond strengths, with rotary-prepared specimens having significantly higher mean bond strengths versus laser prepared specimens. Within each preparation type, in both dentin and enamel, acid etch was better than laser etch, and laser etch was better than no etch. Scanning electron microscopy of laser-ablated specimens demonstrated significant surface scaling and subsurface fissuring beyond normal resin penetration depth.

SIGNIFICANCE

Adhesion to laser-ablated or laser-etched dentin and enamel was inferior to that of conventional rotary preparation and acid etching.

Morphological comparative study on ablation of dental hard tissues at cavity preparation by Er:YAG and Er,Cr:YSGG lasers

OBJECTIVE

The purpose of this study was to evaluate morphologically the dental hard tissue ablation at the class V cavity preparation by two types of laser devices: Er:YAG and Er,Cr:YSGG lasers in vitro.

BACKGROUND DATA

There have been no reports on the comparative study of dental tissue ablation at cavity preparation by Er:YAG and Er,Cr:YSGG lasers.

METHODS

Twenty-two extracted human mature molar teeth were used in this study and divided into two groups of 11 teeth each. The teeth of the Er:YAG laser-irradiated group were irradiated at the parameters of 250 mJ/pulse and 15 Hz with water spray, and those of the Er,Cr:YSGG laserirradiated group were irradiated at the parameters of 5 Wand 20 Hz with water spray. After cavity preparation, the teeth were dehydrated, coated with platinum, and examined by scanning electron microscopy.

RESULTS

Both of the laser devices were capable of ablating dental hard tissues, but similar, irregular, and rugged surface aspects with different depths were observed. Open dentinal tubules at the cavities prepared by Er,Cr:YSGG laser were more clearly visible than those prepared by Er:YAG laser. Smaller width and stripped surfaces were observed on the cavities prepared by Er,Cr:YSGG laser.

CONCLUSION

The results suggested that there is little difference between the two types of lasers-Er:YAG and Er,Cr:YSGG lasers-morphologically for class V cavity preparation, because both lasers were capable of preparing class V cavities, and the morphological features of the irradiated surfaces were very similar.

Comparative study of the dentin/adhesive systems interface after treatment with Er:YAG laser and acid etching using scanning electron microscope

BACKGROUND AND OBJECTIVES

To assess dentin/adhesive systems interface after dentin conditioning with Er:YAG laser.

STUDY DESIGN/MATERIALS AND METHODS

Twenty-four dentin half-disks were assigned to 3 groups: All Bond 2 (AB); Optibond Solo Plus (OP); and Clearfil Liner Bond 2V (CL), which were divided into three sub-groups, according to dentin surface treatment: Er:YAG laser; Er:YAG laser plus acid; acid solely. After the adhesive protocol, specimens were embedded in resin, sectioned, and prepared for SEM analysis. Each area was examined under 1,500x magnification to assess the hybrid layer.

RESULTS

Acid conditioning provided to AB and OP thick and homogeneous hybrid layer, as well as conical and uniform tags. The same pattern was observed for CL. In general, dentin treatment with laser, even when associated to acid, promoted irregular and thin hybrid layer, as well as scarce and thin tags.

CONCLUSIONS

Er:YAG laser influenced the adhesive systems interface, hampering hybrid layer formation.

Structural Changes of Er:YAG Laser–Irradiated Human Dentin

OBJECTIVE

The aim of this study was to investigate the phase, compositional, and morphological changes of Er:YAG laser-irradiated dentin.

BACKGROUND DATA

To date, nothing comprehensive has been reported about the phase and compositional changes of human dentin after Er:YAG laser irradiation.

METHODS

The human dentin was irradiated by Er:YAG laser with irradiation energies from 300 mJ/pulse-10 pps-10 sec to 700 mJ/pulse-10 pps-10 sec with and without water spray. After irradiation, the specimens were analyzed by means of x-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM).

RESULTS

After exposure to Er:YAG laser, dentin showed no phase changes on the x-ray diffractometer. In Fourier transform infrared analysis, two absorption bands at 2200 and 2015 cm(-1) could be traced on dentin treated by Er:YAG laser with irradiation energies beyond 300 mJ/pulse-10 pps-10 sec and without water spray. The OH(-) band disappeared at 1630 cm(-1). Scanning electron micrographs revealed that laser energy of 500 mJ/pulse-10 pps-10 sec was sufficient to prompt melting and recrystallization of dentin crystals.

CONCLUSIONS

Our study demonstrated that Er:YAG laser irradiation on dentin with water spray would not significantly change the structure and composition. Therefore, water cooling is important for reducing the thermal effect of Er:YAG laser.

Morpho-structural aspects of Er:YAG-prepared class V cavities

OBJECTIVE

The aim of this study was to evaluate the ability of an Er:YAG laser (2960nm) to prepare class V cavities as compared with rotary instruments.

MATERIALS AND METHODS

Twenty-six freshly extracted human molars were selected and randomly distributed in two groups. Non standardized class V cavities were prepared using (group 1) a diamond bur for enamel, plus a tungsten bur for dentin with water irrigation and (group 2) an Er:YAG laser (output parameters, enamel: 1000 mJ, 12Hz, dentin: 500 mJ, 20Hz) with a continuous flow of water.

RESULTS

The SEM examination revealed characteristic micro-irregularities of the lased samples as compared with the conventional prepared cavities: group 1, the walls of the cavities were slightly curved and a smear layer plus muds covered peripheric walls as well as the depth of the cavity; rare dentinal tubules were opened; linear and circular surface irregularities were observed on the dentin; and group 2, the walls of the cavities were irregular, jagged; photo-ablation creates a real cleavage of hydroxyapatite prisms with respect to the enamel prism pathway; an homogeneous dentin with opened dentinal tubules covered the depth of the cavities; intertubular dentin is selectively more ablated than Er-YAG the peritubular dentin.

CONCLUSIONS

Jagged outline as well as opened dentinal tubules are the main characteristics of the Er-YAG prepared class V cavities. Further investigations (ulstrastructural, histochemical properties of the lased dentin, resistance to traction of bonded resins) should be conducted.

Scanning electron microscopic evaluation of resin-dentin interface after Er:YAG laser preparation

BACKGROUND AND OBJECTIVES

The aim of this study was to observe the morphological characteristics of dentin-resin interfaces when a composite resin was bonded to Er:YAG laser irradiated dentin.

STUDY DESIGN/MATERIALS AND METHODS

Human dentin surfaces were divided into three equal areas. One third was prepared using a carbide bur and etched with phosphoric acid, the second third was conditioned using an Er:YAG laser, the third one was irradiated and etched. A hybrid composite resin was bonded on dentin surfaces using a single-component adhesive system. Longitudinal sections were exposed to 5 N HCl then to 1% NaOCl. The thickness of the hybrid layer and the dimensions of the resin tags were measured using scanning electron microscopy (SEM) pictures and an image analysis software.

RESULTS

When acid etching was performed, a hybrid layer as well as the characteristic funnel-shaped resin tags were observed. When Er:YAG laser was used alone, no hybrid layer could be detected. The resin tags appeared thinner and exhibited a cylindrical shape.

CONCLUSIONS

The acid pre-treatment of the irradiated surface allowed both the seal of the dentinal surface and the increase of the diameter of the resin tags.

Pulpal temperature increases with Er:YAG laser and high-speed handpieces

STATEMENT OF PROBLEM

During tooth preparation, both high-speed handpieces and lasers generate heat, which, if not controlled, can cause pulpal necrosis.

PURPOSE

The aim of this study was to compare temperature increases produced by a high-speed dental handpiece with those produced by a relatively new instrument, the Er:YAG (erbium: yttrium-aluminum-garnet) laser.

MATERIALS AND METHODS

Thirty bovine mandibular incisors were reduced to an enamel/dentin thickness of 2.5 mm. Class V preparations were completed to a depth of 2.0 mm, measured with a caliper or by a mark on the burs. A thermocouple was placed inside the pulp chamber to determine temperature increases (degrees C). Analysis was performed on the following groups (n=10): Group I, high-speed handpiece without water cooling, Group II, high-speed handpiece with water cooling (30 mL/min), and Group III, the noncontact Er:YAG laser (2.94 microm at 350 mJ/10 Hz) with water cooling (4.5 mL/min). The temperature increases were recorded by a computer linked to the thermocouples. The data were analyzed using the Kruskal-Wallis test. The Dunn multiple comparison test was used as post hoc test (alpha=.05).

RESULTS

The average temperature rises were: 11.64 degrees C (+/- 4.35) for Group I, 0.96 degrees C (+/- 0.71) for Group II, and 2.69 degrees C (+/- 1.12) for Group III. There were no statistical differences between Groups II and III; both II and III differed from Group I significantly (P=.000 and P=.002, respectively).

CONCLUSION

The preparations made with the high-speed and the laser instrument generated similar heat increases under water cooling. Water cooling was essential to avoid destructive temperature increases when using both the high-speed handpiece and laser.

Preparation of root canal orifices by Er:YAG laser irradiation: in vitro and clinical observations

OBJECTIVE

The purpose of the present study was to evaluate the effectiveness of Er:YAG laser irradiation for preparation of root canal orifices in extracted human teeth and several clinical cases.

BACKGROUND DATA

Few studies with sufficient data have been conducted in this area.

MATERIALS AND METHODS

Orifices of 42 extracted human teeth were prepared by conventional methods using a Peeso reamer or Er:YAG laser device at 250 mJ/pulse and 8 Hz. In the clinical study, the orifices of 11 teeth from 11 patients with irreversible pulpitis were prepared by Er:YAG laser irradiation at 160 mJ/pulse and 8 Hz. Teeth were carefully irradiated using non-contact methods. Evaluation was performed by visual inspection, stereoscopy, radiography, and scanning electron microscopy (SEM). In addition, the efficiency of using the Er:YAG laser was evaluated.

RESULTS

In the in vitro study, canal orifices were clearly exposed by laser irradiation in all specimens. In 31 of 36 teeth (86%), orifices were successfully prepared without ledge formation or perforation. SEM observations revealed that irradiated surfaces were slightly rough and scaly, but essentially free from debris and smear layer. In the clinical study, orifices were successfully prepared in 10 of 11 teeth (91%), and no ledge formation or perforation was observed.

CONCLUSION

These results suggest that the preparation of root canal orifices by Er:YAG laser irradiation may be useful in most cases, if appropriate parameters are selected.

Effects of the Er:YAG laser irradiation on titanium implant materials and contaminated implant abutment surfaces

OBJECTIVE

The purpose of this study was to examine the morphological changes and temperature increases of the titanium after Er:YAG laser irradiation, and also to investigate the effect of this laser on debridement of contaminated healing abutments.

BACKGROUND DATA

Mechanical instruments have been used for the cleaning of implant abutment surfaces, however, most of them are not appropriate for the application to titanium surface. Recently, the Er:YAG laser has been expected to have a promising ability for the debridement of implant surface.

MATERIALS AND METHODS

Experiments were composed of three parts. At first, ten titanium round plates were exposed to the Er:YAG laser irradiation at 30-200 mJ/pulse and the surface changes were observed by stereomicroscope and scanning electron microscope. Secondly, the surface temperature changes of 60 titanium plates during and after Er:YAG laser irradiation at 30 and 50 mJ/pulse were measured by thermographic equipment. At last, calculus on the surface of six contaminated healing abutments was removed by Er:YAG laser or ultrasonic scaler, and the treated surfaces were examined by stereomicroscope.

RESULTS

Under 50 mJ/pulse, distinct morphological changes were not observed and the elevation of surface temperature was minimal, especially in the use of water-cooling. The Er:YAG laser at 30 mJ/pulse and 30 Hz with water spray was capable of effectively removing plaque and calculus on the implant abutments without injuring their surfaces.

CONCLUSION

This study indicates that the Er:YAG laser can be a novel technical modality for the debridement of implant abutment surface.

Morphological and microleakage studies of the cavities prepared by Er:YAG laser irradiation in primary teeth

OBJECTIVE

The purposes of this study were to investigate cavity surfaces morphologically, and compare microleakage at cavities prepared by Er:YAG laser after composite resin restoration versus conventional mechanical treatment in human primary teeth in vitro.

BACKGROUND DATA

There have been few reports on microleakage at cavities prepared by Er:YAG laser irradiation.

MATERIALS AND METHODS

A total of 30 cavities (class V) in human primary teeth were used. Half of the cavities were prepared by an Er:YAG laser system at 300 mJ pulse energy and 4 Hz, and the other half were prepared with a high-speed diamond bur. Five cavities from each group were investigated by scanning electron microscopy (SEM) and histopathological examination. Remaining cavities were filled with a composite resin without an acid-etching technique and then subjected to microleakage test in 0.6% rhodamine B solution under thermocycling.

RESULTS

Microleakage (score: 2.45 +/- 1.07) at cavities prepared by laser was significantly less than that by bur (score: 1.30 +/- 0.95; p < 0.05). SEM observation showed that, compared with the relatively flat appearance of cavities prepared by bur, cavity margins prepared by laser were irregular but there was almost no smear layer at the cavity walls.

CONCLUSION

It can be concluded that cavity surfaces prepared by Er:YAG laser are irregular, but microleakage at cavities prepared by the laser after filling with composite resin is better than that by mechanical bur using the dye penetration method.

Clinical assessment of Er,Cr:YSGG laser application for cavity preparation

In this study, an erbium,chromium:YSGG (Er,Cr:YSGG) laser emitting at a wavelength of 2.78 microm was clinically applied to remove caries and prepare cavities, and the clinical outcome was evaluated. Effective clinical application of Er,Cr:YSGG laser had been expected from previous studies. This study included 44 patients (26 females, 18 males; aged 23-58) with a total of 50 cavity preparations by the Er,Cr:YSGG laser irradiation at 3-6 W with water spray. Patient acceptance and prognosis were evaluated. Most cases (94%) were prepared without anesthesia, and no pain was felt in 34 cases (68%). No adverse reaction was observed in any of the cases, and patient acceptance for this system was favorable. All cases had a good prognosis. In 45 cases (90%), overall clinical evaluation was satisfactory. From the present study, it can be concluded that the Er,Cr:YSGG laser system is an efficient, effective, and safe device for caries removal and cavity preparation.