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

Restoration Integrity in Primary Teeth Prepared Using Erbium/Yttrium-Aluminum-Garnet Laser: A Randomized Split-Mouth Clinical Study

The most frequently used and universally accepted technique for removing caries is mechanical ablation of decayed tissues by rotating drills. New minimally invasive strategies, such as the use of lasers to perform highly controlled tissue ablation, have been introduced in dental practice. The aim of this study was to assess and compare treatment with a 2940 nm erbium/yttrium-aluminum-garnet (Er:YAG) laser versus a conventional rotary treatment during cavity preparation in children with regard to restoration integrity. In a randomized, controlled, blinded trial using a split-mouth design, 40 (9-12-year-old) children with 80 carious primary molars were included. The cavity in one quadrant was randomized to be treated conventionally using a bur, while the cavity in the other quadrant was prepared using an Er:YAG laser. At the one-year follow-up, clinical examinations were conducted to assess the integrity of the restorations according to the Ryge criteria. The data were analyzed using SPSS version 22 (IBM Inc., Chicago, IL, USA). The average age of the participants was 9.4 ± 1.29 years. Males accounted for 51.4% of the participants. The Ryge criteria showed clinical success of restorations, and there was no discernible difference between the conventional and laser intervention techniques. Over one year, no statistically significant differences in the clinical integrity based on the Ryge criteria were found following class I cavity preparation in primary teeth with either procedure.

Ablation Precision and Thermal Effects of a Picosecond Infrared Laser (PIRL) on Roots of Human Teeth: A Pilot Study Ex Vivo

BACKGROUND/AIM

Picosecond infrared laser (PIRL) was investigated regarding its possible therapeutic application in cutting dental roots.

MATERIALS AND METHODS

Extracted human teeth were processed in the root area by laser ablations followed by histological evaluation. Dentin adjacent to the cutting surface was evaluated morphometrically.

RESULTS

PIRL produced clearly defined cutting boundaries in dental roots. At the bottom of the cavity, the ablation surface became slightly concave. Heat development in this scantly hydrated tissue was considerable. We attributed the excess heating effects to heat accumulation due to multiple pulse overlap across a limited scan range imposed by tooth geometries.

CONCLUSION

Defined areas of the tooth root may be treated using the PIRL. For clinical translation, it would be necessary to improve beam delivery to facilitate beam steering for the intended oral application (e.g. by using a fiber) and identify optimal repetition rates/scan speeds combined with cooling techniques to minimize accumulated heat within ablation cavities.

Effect of Er:YAG laser energy densities on thermally affected dentin layer: Morphological study

BACKGROUND AND AIMS

Physical and chemical composition of dentin is subject to modification when irradiated with Er:YAG laser. Temperature rise causes water evaporation and micro-mechanical ablation of dentin. The misuse of laser parameters could affect negatively dentin collagen fibers leading to failure in bonded composite restorations. The aim of this in vitro study was to evaluate the effect of Er:YAG laser radiation at different levels of energy on the morphology of thermally affected dentin layer.

MATERIALS AND METHODS

Forty-eight freshly extracted human third molars were randomly divided into six groups (n = 8). In all groups, except for the control groups, dentin was subject to irradiation with H02 handpiece Er:YAG laser in non-contact mode (SSP mode = 50 µs; 10 Hz; speed of 1 mm/second; air 6 mL/min; and water 4 mL/min) with the following levels of energy (40, 60, 80, 100, and 120 mJ) respectively. Teeth were sliced longitudinally. Photo-ablated cavities were observed. The cavity depth and dentin fiber collagen deterioration were measured.

RESULTS

Laser irradiation increased the depth of dentinal crater from 46.57 µm to 178.2 µm, when energy level increased from 40 mJ to 120 mJ. A superficial black layer, representing dentinal affected collagen fibers, was present in all groups except for control group. When comparing the thickness of the black layer, there was no significant difference between groups. It increased at 40 mJ to 28.17 µm then decreased to 15.19 µm at 60 mJ and then increased again for 80 mJ to 19.93 µm, 100 mJ to 22.87 µm and 120 mJ to 28.53 µm. Only one group (60 mJ) showed low values and significant difference as compared to the other irradiated groups, when multiple comparisons tests (ANOVA) were made using Newman-Keuls test.

CONCLUSION

Dentin organic matrix presented the minimum alteration when Er:YAG laser is used specifically at an appropriate level of energy (60 mJ).

A Randomized Controlled Trial Comparing Er:YAG Laser and Rotary Bur in the Excavation of Caries - Patients' Experiences and the Quality of Composite Restoration

Objective

The aim of this study was to evaluate patients´ experiences of two excavation methods, Er:YAG laser and rotary bur and time required by the methods as well as objective assessments of quality and durability of restorations over a two-year period.

Methods

A prospective, single-blind, randomized and controlled investigation was performed. Patients aged 15 to 40 years with at least two primary caries lesions, which had been radiographically assessed as of the same size, were recruited. In each patient, one cavity was excavated using rotary bur and one using Er:YAG laser technique. The time required for excavations and, where applicable, local anaesthesia, was measured during the treatments. Patient experiences were measured using questionnaires. The quality and durability of restorations were assessed over a two-year period in accordance with modified Ryges criteria and radiographs. Twenty-five patients (mean age 22.6 years) participated in the study. In total, 56 cavities were included of which 28 were treated with Er:YAG laser and 28 were treated with a rotary bur.

Results

The patients associated the laser method with less discomfort. The mean time for excavation by laser was three times longer than by rotary bur (13.2 min vs. 4.3 min, P<0.0001). Over a two-year period, no statistically significant differences with regard to quality or durability could be seen between the restorations associated with the methods.

Conclusion

The Er:YAG laser technique was more time-consuming than the rotary bur. Despite this, the laser technique caused less discomfort and was preferred as an excavation method by patients.

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.

Microindentation hardness and calcium/phosphorus ratio of dentin following excavation of dental caries lesions with different techniques

BACKGROUND

The aim of this in vitro study was to evaluate the microindentation hardness and chemical composition of residual dentin left at the cavity bottom following removal of carious dentin using the Carisolv chemomechanical and Er:YAG laser caries excavation methods in comparison with the conventional tungsten-carbide bur excavation.

METHODS

Sixty-nine extracted permanent teeth with occlusal dentin caries were assigned into three groups according to caries removal technique. Carious dentin excavation was guided by tactile method and a caries-staining dye. In stereomicroscope images (100×) of the samples, the presence or absence of residual caries was defined. The Knoop hardness value of the cavity floor was determined and atomic analysis of treated cavities was performed by energy dispersive X-ray spectroscopy.

RESULTS

The Knoop hardness value of residual dentin left at the cavity bottom was lower (One-way ANOVA, Dunnett-C, p < 0.05) and the percentage of samples with remaining carious dentin was higher after Carisolv excavation than those obtained after conventional and laser excavations (Kruskal-Wallis, Mann-Whitney U, p < 0.05). No significant differences were found between the quantities of calcium content (Ca wt%), phosphorus content (P wt%) and calcium/phosphorus ratio of the cavities treated by three techniques (Kruskal-Wallis, Mann-Whitney U, p > 0.05).

CONCLUSION

The results indicated that Er:YAG laser was more comparable to conventional bur excavation than chemomechanical method in the efficacy of caries removal with regard to microindentation hardness of remaining dentin and both Carisolv gel and Er:YAG laser did not alter chemical composition of residual dentin in the treated cavities.

Lasers for caries removal in deciduous and permanent teeth

BACKGROUND

Despite considerable improvements in oral health, dental caries continue to be a public health issue. The most frequently used, and universally accepted technique, to remove caries is through mechanical ablation of decayed tissues by means of rotating drills (diamond or tungsten carbide, or both). In the past few decades, the introduction of adhesive filling materials (resin composites) has affected cavity filling procedures by reducing its retention needs, with advantages for dental tissue conservation. Consequently, new minimally invasive strategies were introduced into dental practice, such as the use of lasers to perform highly controlled tissue ablation. Laser use has also raised expectations of limiting pain and discomfort compared to using drills, as well as overcoming drill phobia.

OBJECTIVES

The main objective of the review was to compare the effects of laser-based methods to conventional mechanical methods for removing dental caries in deciduous and permanent teeth.

SEARCH METHODS

We searched the following electronic databases: Cochrane Oral Health's Trials Register (searched 22 June 2016), Cochrane Central Register of Controlled Trials (CENTRAL; 2016, Issue 5) in the Cochrane Library (searched 22 June 2016), MEDLINE Ovid (1946 to 22 June 2016), Embase Ovid (1980 to 22 June 2016), ProQuest Dissertations and Theses (1980 to 22 June 2016), Zetoc (limited to conference proceedings) (1993 to 22 June 2016), and ISI Web of Knowledge (limited to conference proceedings) (1990 to 22 June 2016). We checked the reference lists of relevant articles to identify additional studies. We searched the US National Institutes of Health Ongoing Trials Register ClinicalTrials.gov and the World Health Organization International Clinical Trials Registry Platform for ongoing trials.

SELECTION CRITERIA

We included randomised controlled trials, split-mouth trials and cluster-randomised trials (irrespective of their language) comparing laser therapy to drill ablation of caries. We included participants of any age (children, adolescents and adults).

DATA COLLECTION AND ANALYSIS

Two review authors independently screened titles and abstracts of citations identified by the review search strategy. Two review authors independently evaluated the full text of relevant primary studies, assessed risk of bias and extracted data. We used standard methodological procedures expected by Cochrane.

MAIN RESULTS

We included nine randomised trials, published between 1998 and 2014, involving 662 participants. The population consisted of both children and adolescents in four trials, only adults in four trials, and both children/adolescents and adults in one trial. Four studies examined only permanent teeth, and five studies evaluated both deciduous and permanent teeth. Six trials used Er:YAG (erbium-doped yttrium aluminium garnet) lasers, two trials employed Er,Cr:YSGG (erbium, chromium: yttrium-scandium-gallium-garnet) lasers, and one trial used Nd:YAG (neodymium-doped yttrium aluminium garnet) laser.Overall, the trials had small sample sizes, and the majority were at unclear or high risk of bias. The primary outcomes were evaluated in a limited number of trials (removal of caries (four trials (but only two reported quantitative data)); episodes of pain (five studies)). There was insufficient evidence to suggest that either lasers or drill were better at caries removal (risk ratio (RR) 1.00, 95% confidence interval (CI) 0.99 to 1.01; 2 studies; 256 treated caries; P = 0.75; I² = 0%; low-quality evidence).The incidence of moderate or high pain was greater in the drill group compared to the laser group (RR 0.40, 95% CI 0.28 to 0.57; 2 studies; 143 participants; P < 0.001; I² = 50%). Similarly, the need for anaesthesia was significantly higher in the drill group than in the laser group (RR 0.25, 95% CI 0.10 to 0.65; 3 studies; 217 children/adolescents; P = 0.004; I² = 0%).In terms of marginal integrity of restoration, there was no evidence of a difference between laser and drill comparisons evaluated at 6 months (RR 1.00, 95% CI 0.21 to 4.78; 3 studies), 1 year (RR 1.59, 95% CI 0.34 to 7.38; 2 studies), or 2 years (RR 1.00, 95% CI 0.21 to 4.74; 1 study).There was no evidence of a difference for durability of restoration between laser therapy or drill at 6 months' follow-up (RR 2.40, 95% CI 0.65 to 8.77; 4 studies), at 1 year (RR 1.40, 95% CI 0.29 to 6.78; 2 studies) or at 2 years' follow-up (RR 0.50, 95% CI 0.02 to 14.60; 1 study).Only two trials investigated the recurrence of caries, but no events occurred during 6 months' follow-up.There was insufficient evidence of a difference between laser or drill in terms of pulpal inflammation or necrosis at 1 week (RR 1.51, 95% CI 0.26 to 8.75; 3 studies) and at 6 months (RR 0.99, 95% CI 0.10 to 9.41; 2 studies).

AUTHORS' CONCLUSIONS

Given the low quality of the body of evidence, we concluded that evidence was insufficient to support the use of laser as an alternative to traditional drill therapy for caries removal. We found some evidence in favour of laser therapy for pain control, need of anaesthesia and patient discomfort, but, again, the body of evidence was of low quality. Additional well-designed, randomised trials investigating the most relevant outcomes are needed.

Applications of Light Amplification by Stimulated Emission of Radiation (Lasers) for Restorative Dentistry

Light amplification by stimulated emission of radiation (laser) has been used widely in a range of biomedical and dental applications in recent years. In the field of restorative dentistry, various kinds of lasers have been developed for diagnostic (e.g. caries detection) and operative applications (e.g. tooth ablation, cavity preparation, restorations, bleaching). The main benefits for laser applications are patient comfort, pain relief and better results for specific applications. Major concerns for using dental lasers frequently are high cost, need for specialized training and sensitivity of the technique, thereby compromising its usefulness particularly in developing countries. The main aim of this paper is to evaluate and summarize the applications of lasers in restorative dentistry, including a comparison of the applications of lasers for major restorative dental procedures and conventional clinical approaches. A remarkable increase in the use of lasers for dental application is expected in the near future.

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.

Selective removal of carious human dentin using a nanosecond pulsed laser operating at a wavelength of 5.85 μm

Less invasive methods for treating dental caries are strongly desired. However, conventional dental lasers do not always selectively remove caries or ensure good bonding to the composite resin. According to our previous study, demineralized dentin might be removed by a nanosecond pulsed laser operating at wavelengths of around 5.8 μm . The present study investigated the irradiation effect of the light on carious human dentin classified into "remove," "not remove," and "unclear" categories. Under 5.85-μm laser pulses, at average power densities of 30 W/cm² and irradiation time of 2 s, the ablation depth of "remove" and "not remove," and also the ablation depth of "unclear" and "not remove," were significantly different (p<0.01 ). The ablation depth was correlated with both Vickers hardness and Ca content. Thus, a nanosecond pulsed laser operating at 5.85  μm proved an effective less-invasive caries treatment.

Use of new minimum intervention dentistry technologies in caries management

Preservation of natural tooth structure requires early detection of the carious lesion and is associated with comprehensive patient dental care. Processes aiming to detect carious lesions in the initial stage with optimum efficiency employ a variety of technologies such as magnifying loupes, transillumination, light and laser fluorescence (QLF® and DIAGNOdent® ) and autofluorescence (Soprolife® and VistaCam®), electric current/impedance (CarieScan(®) ), tomographic imaging and image processing. Most fluorescent caries detection tools can discriminate between healthy and carious dental tissue, demonstrating different levels of sensitivity and specificity. Based on the fluorescence principle, an LED camera (Soprolife® ) was developed (Sopro-Acteon, La Ciotat, France) which combined magnification, fluorescence, picture acquisition and an innovative therapeutic concept called light-induced fluorescence evaluator for diagnosis and treatment (LIFEDT). This article is rounded off by a Soprolife® illustration about minimally or even non-invasive dental techniques, distinguishing those that preserve or reinforce the enamel and enamel-dentine structures without any preparation (MIT1- minimally invasive therapy 1) from those that require minimum preparation of the dental tissues (MIT2 - minimally invasive therapy 2) using several clinical cases as examples. MIT1 encompasses all the dental techniques aimed at disinfection, remineralizing, reversing and sealing the caries process and MIT2 involves a series of specific tools, including microburs, air abrasion devices, sonic and ultrasonic inserts and photo-activated disinfection to achieve minimal preparation of the tooth. With respect to minimally invasive treatment and prevention, the use of lasers is discussed. Furthermore, while most practices operate under a surgical model, Caries Management by Risk Assessment (CaMBRA) encourages a medical model of disease prevention and management to control the manifestation of the disease, or keep the oral environment in a state of balance between pathological and preventive factors. Early detection and diagnosis and prediction of lesion activity are of great interest and may change traditional operative procedures substantially. Fluorescence tools with high levels of magnification and observational capacity should guide clinicians towards a more preventive and minimally invasive treatment strategy.

Effect of Nd:YAG laser pulse energy on mercury vapor release from the dental amalgam

OBJECTIVE

The aim of this study was to evaluate the effect of different pulse energies of Nd:YAG laser on the amalgam ablation, and its effect on the amount of mercury vapor release from amalgam.

BACKGROUND DATA

Toxic vapor release from amalgam restorations at the laser focus site is possible.

MATERIALS AND METHODS

Forty-five amalgam samples (4 mm in diameter and 5 mm in height) were placed in sealed containers and underwent Nd:YAG laser irradiation with pulse energies of 50, 150, and 250 mJ at a distance of 1 mm from the amalgam surface for 4 sec. Subsequently, 150 mL of air was collected from the inside of the container using an Apex Pump to analyze the amount of mercury vapor in the air samples using a mercury vapor analyzer. Data were analyzed using Kruskal-Wallis and Mann-Whitney U tests (p<0.05).

RESULTS

The amount of mercury vapor release significantly increased with an increase in the pulse energy of Nd:YAG laser (p<0.001). In addition, the amount of mercury vapor release with 250 mJ pulse energy was significantly higher compared with the standard mercury vapor concentration (50 μg/m(3)) (p<0.001). Nd:YAG laser produced cavities on the amalgam surface, which increased in size with an increase in the energy of the laser beam.

CONCLUSIONS

The amount of mercury vapor significantly increased with an increase in the pulse energy of the laser beam, and was significantly higher than the standard mercury vapor concentration with 250 mJ pulse energy.

Laser in caries treatment--patients' experiences and opinions

OBJECTIVES

The aim of this study was to obtain a deeper understanding of patient's experiences and perspectives after dental caries treatment with Er:YAG laser technology.

METHODS

Twelve patients aged 15-30 years who had undergone at least one laser caries excavation agreed to participate in an interview study. All the interviews were tape recorded and transcribed by a transcription agency. The transcribed texts were analysed using manifest and latent qualitative content analysis.

RESULTS

The categories in this study were identified as choosing laser, understanding laser, encouraging dental care and my oral health. The motivation for laser treatment was described as dental fear in general, specific fear of needles or discomfort with the drill. The informants described the dentist's role as initiators of treatment and willing or unwilling facilitators. Laser treatment was described as safer and more carefully considered treatment. They felt generally safe with laser and were able to relax during the treatment. All interviewers described a positive impression of the laser, and words like 'up to date' and 'future-oriented' were used to describe laser. Laser treatment was considered less painful.

CONCLUSIONS

The results indicate that patients find laser a feasible and convenient treatment option.

A systematic review on fluoridated food in caries prevention

OBJECTIVE

This paper aims to provide a systematic review of the caries-prevention effect of fluoridated food, excluding water. The main aim of this review was to evaluate the presence of scientific evidence relating to the effects of fluoride intake via food on the occurrence of carious lesions. The outcome was defined as a clinical outcome, so only papers evaluating a decrease in caries indices were included.

MATERIALS AND METHODS

Relevant databases (Medline®, Embase®, The Cochrane Library) were searched. The date range was set from 01.01.1966 to 03.31.2011. One hundred and thirty-nine reports were identified and assessed. Only three papers fulfilled the inclusion criteria and were discussed in detail.

RESULTS

No paper related to the use of fluoridated salt in caries prevention fulfilled the inclusion criteria. The use of milk as a vehicle for providing additional fluoride in a dental public health programme was evaluated in two papers. The consumption of fluoridated milk was an effective measure to prevent caries in the primary teeth. The use of fluoridated sugar demonstrated a reduction in caries increment in the permanent dentition in one paper.

CONCLUSIONS

Literature on the effectiveness of fluoridation in foods in caries prevention is scant and almost all the studies have been conducted in children. There is low evidence that the use of milk fluoridation is effective in reducing the caries increment.

Thermal effects and morphological aspects of human dentin surface irradiated with different frequencies of Er:YAG laser

This study reports the effects on micromorphology and temperature rise in human dentin using different frequencies of Er:YAG laser. Sixty human dentin fragments were randomly assigned into two groups (n = 30): carious or sound dentin. Both groups were divided into three subgroups (n = 10), according to the Er:YAG laser frequency used: 4, 6, or 10 Hz (energy: 200 mJ; irradiation distance: 12 mm; and irradiation time: 20 s). A thermocouple adapted to the tooth fragment recorded the initial temperature value (°C); then, the temperature was measured after the end of the irradiation (20 s). Morphological analysis was performed using images obtained with scanning electron microscope. There was no difference between the temperatures obtained with 4 and 6 Hz; the highest temperatures were achieved with 10 Hz. No difference was observed between carious and sound dentin. Morphological analyses revealed that all frequencies promoted irregular surface in sound dentin, being observed more selectively ablation especially in intertubular dentin with tubule protrusion. The caries dentin presented flat surface for all frequencies used. Both substrates revealed absence of any signs of thermal damage. It may be concluded that the parameters used in this study are capable to remove caries lesion, having acceptable limits of temperature rise and no significant morphological alterations on dentin surface.