A clinical evaluation of an Erbium:YAG laser for dental cavity preparation

Assessment of Smear Layer Formation After Caries Removal Using Erbium Laser and Papain-Based Chemo-Mechanical Caries Removal Agent: An In Vitro Scanning Electron Microscopy Study

Introduction With the advancement in the field of adhesive dentistry, there has been a significant and groundbreaking shift toward the adoption of minimally invasive caries removal techniques where substrate modification is known to enhance adhesive bonding. The smear layer has always been controversial, as its modification helps in bonding, but if contaminated with bacteria, it compromises the formation of a satisfactory marginal seal. Thus, the recognition of the role played by the smear layer highlights the importance of the type of caries removal method employed. Hence, the aim of the present study was to assess and compare smear layer formation after caries removal using an erbium laser and chemo-mechanical caries removal agent by scanning electron microscopy. Methods The study involved the evaluation of 30 extracted human molars with occlusal caries. Based on the method of caries excavation, the samples were allocated into two separate groups: group 1 - caries removed using erbium laser (Waterlase, Biolase, Lake Forest, CA); group 2 - caries removed using papain-based chemo-mechanical caries removal agent (Carie Fix, Dengen Dental, Bahadurgarh, India). To assess the smear layer, the samples underwent examination using a scanning electron microscope at 1500x and 3000x magnification after removal of caries. Statistical analysis was done using SPSS version 22 software (IBM Corp., Armonk, NY). Mann-Whitney test was used to compare the mean smear layer (nonparametric) between both groups. Results Group 1 (Er:YAG laser) showed significantly greater removal of the smear layer than group 2 (papain-based chemo-mechanical caries removal agent) on the excavated caries surfaces (p < 0.001). In group 1, the dentinal tubules exhibited greater patency when compared to the partial patency observed in group 2. Conclusion Both techniques for caries removal were effective; however, the Er:YAG laser method was determined to be more efficient in comparison to the chemo-mechanical agent. These caries removal methods can be considered the future of minimally invasive dentistry.

Evaluation of the Erbium-doped Yttrium Aluminum Garnet Laser and the Conventional Method on Pain Perception and Anxiety Level in Children during Caries Removal: A Randomized Split-mouth Study

Aim and objective

To assess and compare children's anxiety level and pain perception during cavity preparation using an erbium-doped yttrium aluminum garnet (Er:YAG) laser vs traditional rotational treatment.

Materials and methods

A randomized, controlled, split-mouth clinical trial was carried out in 35 healthy children with 70 carious primary molars. Teeth were divided equally into two groups according to the method of treatment. A bur was used to prepare the cavity in one quadrant, while an Er:YAG laser was used to prepare the cavity in the other quadrant. Anxiety was assessed using Venham's dental anxiety scale and a fingertip pulse oximeter. The pain was assessed using the Wong-Baker Face Pain Rating Scale, and the number of local anesthesia (LA) needed during both procedures was also considered.

Results

The mean age was 9.4 ± 1.29. Males accounted for 51.4% of the participants. There were no statistically significant variations in pulse rate at the baseline between Er:YAG laser and the conventional treatments. The mean pulse rate was higher during the conventional intervention than during the laser intervention; this difference was statistically significant vs the baseline pulse rate. The mean pulse rate with the conventional method was significantly higher during and after cavity formation than with the laser method. The Er:YAG laser and the conventional groups showed statistically significant differences in the Venham's and Wong-Baker scores. The scores of both scales were much higher in the conventional group. The number of participants who requested LA during the conventional technique was significantly higher than during the laser procedure.

Conclusion

Using Er:YAG lasers to remove caries produces minimal pain and anxiety and reduces the requirement for LA.

Clinical significance

During cavity preparation, the Er:YAG laser helps children stay calm.

How to cite this article

Abdrabuh RE, El Meligy OAES, Felemban OM, et al. Evaluation of the Erbium-doped Yttrium Aluminum Garnet Laser and the Conventional Method on Pain Perception and Anxiety Level in Children during Caries Removal: A Randomized Split-mouth Study. Int J Clin Pediatr Dent 2023;16(S-1):S39-S44.

Effect of Er: YAG laser irradiation with additional low energy on resin-dentin bonding and morphology of bonded interface

OBJECTIVES

To examine the micro tensile bond strength (μTBS) and the resin-dentin interface on a laser-irradiated dentin surface using two different irradiation methods, with or without additional low-energy irradiation.

METHODS

The flat bovine dentin surface was divided into three groups: i). control group (C group, no irradiation), ii) 80 mJ/pulse Er: YAG laser group (80 group), iii) 80 + 30 mJ/pulse Er: YAG laser group (80 + 30 group, with an additional 30 mJ/pulse). After the roughness of the dentin surface was recorded, Clearfil SE Bond 2 or Clearfil Universal Bond Quick (Kuraray Noritake Dental Inc., Tokyo, Japan) was applied. After the μTBS testing, the failure mode was observed. The bonded interface was assessed using Rhodamine-dye incorporated adhesives and observed by optical coherence tomography.

RESULTS

The dentin surface showed opened dentinal tubules without a smear layer after irradiation. For both adhesives, the μTBS was significantly higher in 80 + 30 group than in the 80 group (p < 0.05). In the 80 group, the thickness of the adhesive layer was not uniform, and the dentin surface was occasionally in direct contact with the composite resin. The failure mode images showed that most of the fractures in the 80 group were at the sub-surface of irradiated dentin. The adhesive layers of the 80 + 30 groups were homogeneous.

CONCLUSIONS

The dentin surface was rough and irregular by 80 mJ irradiation, which might result in an inadequate resin-dentin interface and the weak μTBS. The bonded integrity was mitigated by additional irradiation.

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.

Use of the Er:YAG Laser in Conservative Dentistry: Evaluation of the Microbial Population in Carious Lesions

The aim of this study is to investigate the Erbium:Yttrio-Aluminum-Granate (Er:YAG) laser photothermal and mechanical effects on cariogenic species concentration and on the microbial load composition of therapeutic cavities, in order to evaluate the possible micro-organisms reduction and make a comparison with manual and rotating conventional therapy (CT). A clinical trial was designed, including adults with active deep carious lesions on permanent teeth who were divided into two groups, i.e., control group and intervention group treated with CT and Er:YAG therapy, respectively. Before and after any conservative treatment, two oral samples were collected using a small sterile microbrush scrubbed within the base of the dentinal cavity tissue. The percentage of reduction and the colony-forming units (CFUs) count after Er:YAG and conventional treatments were compared for total microorganisms, including Candida spp., Streptococcus spp., and Lactobacillus spp. The microbial reduction varied from 90.2% to 100% and was significantly observed for total microorganisms and Streptococcus spp. (p < 0.05). The Er:YAG laser shows the potential for clinical applications, especially with paediatric and complicated patients, thanks to its minimally invasive properties and its effect on the reduction of microbial load.

Optical coherence tomography characterizes the roughness and thickness of the heterogeneous layer on cortical bone surface induced by Er:YAG laser ablation at different moisture contents

Background

As an innovative bone ablation tool, pulsed erbium: yttrium-aluminum-garnet (Er:YAG) laser is being used in clinical practice. It faces the same problems as traditional tools: the water content of bone usually changes with the position, while the amount of water spray in the process of laser irradiation is also uncertain. Real-time monitoring of the effects of laser bone ablation is necessary, but effective tools are still lacking. In this study, we examined the feasibility of rapidly and non-destructively evaluating the surface properties of bone after Er:YAG laser irradiation at different moisture contents by optical coherence tomography (OCT).

Methods

Bone specimens (n=90) collected from pig cortical bone were used in this study. All bone specimens had similar volume and surface characteristics after machining. To display the baseline level before Er:YAG laser ablation, a control group (n=10) without dehydration or Er:YAG laser ablation was examined with OCT, scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) spectroscopy. The remaining specimens were randomly divided into four groups (n=20/group) with different moisture content: dried (Group 2 and Group 4) or not dried (Group 1 and Group 3). Pulsed Er:YAG laser (120 mJ/pulse, 20 Hz, 100 µs) was used for perpendicular irradiation with (Group 1 and Group 2) or without (Group 3 and Group 4) water spray. The treated specimens were subjected to SEM, EDX spectroscopy, OCT, and then processed for histological evaluation.

Results

After Er:YAG laser ablation, the melting effect was obvious in the SEM results of the dry groups and non-sprayed groups (Groups 2-4). EDX spectroscopy showed that the content of calcium and phosphorus and their ratios remained unchanged in the undried and with water spray group (Group 1) were the closest to the control group. Three-dimensional (3D) OCT could evaluate the depth and shape of ablation grooves. The roughness of the laser-ablated surface could be visualized by extracting the surface lines from cross-sectional OCT images. The results illustrated that the laser ablation with water spray could achieve a smoother surface. Furthermore, OCT results demonstrated that a layer with high image intensity was generated on the bone surface after laser irradiation. The thickness of these layers showed a correlation with whether or not the laser irradiation was sprayed with water. Histology showed that thin eosin-stained layers were created in all experimental groups, which matched well with OCT results of the layers with high image intensity. No denatured layer was observed in the non-irradiated areas of bone tissues.

Conclusions

OCT could rapidly and non-destructively visualize the bone surface before and after Er:YAG laser ablation at four different moisture contents. The morphology of ablation grooves, as well as the roughness and thickness of the heterogeneous layer on the bone surface, could be characterized quantitatively with good correlation with SEM and histology. This study will promote the development of OCT as an efficient and accurate tool for evaluating laser ablation of bone.

Comparison of Pain and Anxiety Level Induced by Laser vs Rotary Cavity Preparation: An In Vivo Study

Aim

To evaluate and compare the pain perception, anxiety level, and acceptance of Er,Cr:YSGG laser (2780 nm) with a conventional rotary method during cavity preparation in children.

Materials and methods

In a randomized controlled trial, using split-mouth design thirty 6- to 12-year-old children with 60 carious molars were examined. In one quadrant, cavity was prepared conventionally by airotor while, in the other quadrant, Er,Cr:YSGG laser was used. Anxiety was assessed by measuring pulse rate using a fingertip pulse oximeter, while the pain was measured on the Wong-Baker Faces Pain Rating Scale. After the cavity preparation by both the methods, the child was asked about the preference for future treatment of a carious lesion.

Results

Pulse rate was found significantly higher in the airotor group but no significant difference in pulse rate was found in the laser group when compared to the baseline pulse rate. The mean value of pain in the airotor group was slightly higher than the laser group. Fifty-seven percent of children preferred Er,Cr:YSGG laser for cavity preparation in the future.

Conclusion

During cavity preparation, Er,Cr:YSGG laser comes out to be more effective and acceptable, as it is less anxiety-provoking and may cause less pain when compared with the airotor.

Clinical significance

Er,Cr:YSGG laser helps the children to remain calm during the cavity preparation.

How to cite this article

Alia S, Khan SA, Navit S, et al. Comparison of Pain and Anxiety Level Induced by Laser vs Rotary Cavity Preparation: An In Vivo Study. Int J Clin Pediatr Dent 2020;13(6):590-594.

Evaluating and comparing the morphological and histopathological changes induced by erbium:yttrium-aluminum-garnet laser and diamond bur on enamel, dentin and pulp tissue

AIM

Lasers are used for different types of dental treatments. Using the erbium:yttrium-aluminum-garnet (Er:YAG) laser to remove dental hard tissue is simple, advantageous and influences the type of cavity preparation, whether conventional or conservative in nature. The aim of the present study was to evaluate and compare the morphological and histopathological changes in the enamel, dentin and pulp tissue of the teeth treated by Er:YAG laser and conventional burs.

METHODS

A conventional class I cavity was prepared in orthodontic patients by laser and bur. The teeth were extracted and analyzed for morphological changes using a scanning electron microscope, ground sections and histopathological changes under a light microscope.

RESULTS

The time with laser was longer than the conventional methods. The lased cavity showed irregular appearance with absence of smear layer which is suitable for the resin restoration. The ground section and the histopathological study showed no differences between the groups.

CONCLUSION

The Er:YAG laser is effective in the removal of dental hard tissue without damaging the pulp when coupled with ideal energy output. It is widely used in different dental fields. It needs time to be accepted by dentist and patients and further studies are required to explore its advantages.

Efficacy of Caries Removal by Carie-Care and Erbium-doped Yttrium Aluminum Garnet Laser in Primary Molars: A Scanning Electron Microscope Study

Aim

To compare and evaluate morphological changes and bacterial deposits in primary carious molars after caries excavation with Carie-Care, erbium-doped yttrium aluminum garnet (Er:YAG) laser, and round tungsten carbide bur.

Materials and methods

Thirty human carious primary molars extracted for therapeutic reasons were sectioned mesiodistally. These sectioned samples were allocated into three groups (20 samples each): group I: Carie Care, group II: Er:YAG laser, and group III: round tungsten carbide bur. After caries excavation, all samples were processed and examined under conventional light microscope to examine for bacterial deposits. Representative samples from each group were processed and analyzed to examine the morphology of caries-excavated tissue by scanning electron microscope (SEM). Statistical analysis was done using Fisher’s exact test, Kruskal–Wallis test, and Mann-Whitney U test.

Results

The Er:YAG laser showed best results with no smear layer followed by chemomechanically excavated surfaces with Carie-Care. Amount of bacterial deposits was observed to be more in group I while least in group II (p-value < 0.001). Mann-Whitney U test and Fisher’s exact test revealed that there was statistically significant difference among all the three groups.

Conclusion

Among the three different methods of caries excavation, Er:YAG laser was found to be more effective compared with Carie-Care and round tungsten carbide bur.

Clinical significance

Laser-induced caries excavation by Er:YAG laser and chemomechanical method of caries removal by Carie-Care can be considered as future of noninvasive pediatric and preventive dentistry.

How to cite this article: Prabhakar A, Lokeshwari M, Naik SV, Yavagal C. Efficacy of Caries Removal by Carie-Care and Erbium-doped Yttrium Aluminum Garnet Laser in Primary Molars: A Scanning Electron Microscope Study. Int J Clin Pediatr Dent 2018;11(4):323-329.

Er:YAG laser application in caries removal and cavity preparation in children: a meta-analysis

The aim of this meta-analysis was to systematically evaluate the applications of Er:YAG lasers for the removal of caries and cavity preparation in children. The meta-analysis was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and was conducted with data extracted from seven relevant randomized controlled trials (RCTs) published from 1997 to July 2017. The data heterogeneity of each study was assessed by a Q test. We used the heterogeneity results to calculate the standard mean difference (SMD) or relative risk (RR) and 95% confidence interval (95%CI) using STATA version 10.0. The publication bias was evaluated using Begger's test. There were seven randomized controlled trials included in this study. The analysis results indicate that compared to the conventional mechanical method, more time was needed for Er:YAG laser treatment (SMD 1.945, 95%CI 0.942 to 2.948). However, the pain reported by patients was reduced with Er:YAG laser treatment (SMD - 1.013, 95%CI - 1.892 to - 0.196). There were no significant differences between the groups in the complete retention rate (RR 1.021, 95%CI 0.963 to 1.114), the marginal discoloration (RR 1.638, 95% CI 0.240 to 11.986) and the marginal adaptation (RR 1.480, 95%CI 0.257 to 8.515). In conclusion, our data indicate that the time required for Er:YAG laser treatment was longer than that for the conventional mechanical method, but there was less pain associated with the Er:YAG laser treatment. There were no significant differences in the complete retention rate, marginal discoloration, and marginal adaptation between the two groups.

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.

Erbium Laser Technology vs Traditional Drilling for Caries Removal: A Systematic Review with Meta-Analysis

OBJECTIVE

The study aimed to assess the efficacy of erbium laser technology compared with traditional drilling for caries removal.

METHODS

A systematic search was conducted through Medline via PubMed, Embase, Cochrane databases, CNKI till December 2016. Randomised controlled trials, quasi-randomized controlled trials, or controlled clinical trials with data comparing the efficacy of erbium laser technology versus traditional drilling for caries removal were included.

RESULTS

Fourteen studies were selected in our meta-analysis. Erbium laser technology showed an increased time when removing caries compared with drilling (mean difference: 3.48, 95% confidence interval: 1.90-5.06, P < .0001). However, erbium laser technology reduced the requirement for local anesthesia (risk ratio: 0.28, 95% confidence interval: 0.13-0.62, P = .002). Erbium laser technology was also not significantly different to traditional drilling with regard to restoration loss, pulpal vitality, and postoperative sensitivity.

CONCLUSIONS

Erbium laser technology showed an increased time for cavity preparation compared with traditional drilling. However, erbium laser technology reduced the requirement for local anesthesia. There was no significant difference between erbium laser technology and traditional drilling regarding restoration loss, pulpal vitality, and postoperative sensitivity.

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.

Alternative treatment strategies for carious primary teeth: An overview of the evidence

BACKGROUND

Dental decay in children's primary teeth is a major health problem in the Great Britain with, in some areas, nearly 60% of five-year-olds having some experience of caries and 16% already having had at least one tooth extracted. Whilst currently accepted best practice for the management of carious primary teeth involves complete caries removal and placement of a plastic restoration, such conventional treatment is unpopular with general dental practitioners. Indeed, less than 15% of carious cavities in five-year-olds are currently restored and as such, there has been recent interest in alternative 'minimal intervention' treatment techniques for managing dental caries.

REVIEW

This review summarises the literature and also recent research efforts directed towards understanding the role of alternative treatment regimens including: (1) alternative techniques for cavity preparation and excavation and (2) the isolation of the carious process (in some cases, using cariostatic materials) from the oral environment or sealing in dental caries.

Evaluating the efficiency of caries removal using an Er:YAG laser driven by fluorescence feedback control

INTRODUCTION

Caries lesions in dental hard tissues autofluoresce when exposed to light of certain wavelengths, whereas sound tissues do not, and this can be used as an in vitro histological marker for dental caries. Detection of autofluorescence is the basis of KaVo DIAGNOdent™ technology, and provides objective feedback control of laser-stimulated ablation of dental caries for the KaVo Key Laser 3™. This Er:YAG laser operates at 2940nm wavelength, and is effective at removal of infected dental hard tissues. Micro-computed tomography (micro-CT) allows the non-invasive investigation of three-dimensional structures and analysis of mineral density profiles of dentine following laser ablation.

OBJECTIVE

To evaluate removal of infected, demineralised dentine by Er:YAG irradiation with a laser feedback mechanism, using micro-CT.

DESIGN

27 carious teeth (1 control) and 1 sound tooth, treated with the KaVo Key Laser 3™ using a KaVo™ non-contact 2060 handpiece at specific feedback settings, were examined using a Skyscan 1172 Micro-CT, to observe the efficiency of demineralised dentine removal. Grey scale images obtained were colour rendered to assist detection of demineralised tissue if present.

RESULTS

Complete removal of demineralised tissue occurred with laser-stimulated ablation under feedback control at values of 7 and 8 when measured by micro-CT. At greater values, removal of demineralised dentine was incomplete.

CONCLUSION

Examination of dental tissues by micro-CT allowed determination of the efficiency of Er:YAG laser-stimulated ablation. Feedback control of the KaVo Key Laser 3™ appeared to operate like a cut-off switch when infected dentine was eliminated, at a threshold of between 6 and 7.

A qualitative investigation of the views of primary care dentists on participating in prospective studies in the North-West of England

BACKGROUND

There is a poor understanding of to how to recruit and involve primary care dentists in clinical trials.

AIM

To use a qualitative paradigm to explore the views of primary care dentists towards participating in clinical trials and develop an understanding of the factors that facilitate and prevent their involvement. DESIGN, SETTING, SUBJECTS AND METHODS: An iterative approach was undertaken using a focus group (n = 6) followed by phased semi-structured interviews (n = 18). Data were analysed using thematic analysis and constant comparative analysis.

FINDINGS

The semi-structured interviews generated nine codes which were organised into three themes: technical issues for trials in primary dental care, practical issues for research in primary dental care and primary care dentists as research consumers. Overall, primary care dentists had a poor understanding of research methodology and clinical research. Barriers to participation included loss of clinical freedom and control, practice disruption, patient welfare, staff workload, financial loss and time.

CONCLUSIONS

Barriers to primary dental care research need to be overcome through appropriate protocols, funding, training and support. Joint working of primary dental care teams and academic researchers is essential, along with a constructive and open dialogue, if clinical trials are to be successfully undertaken in a practice environment.

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.

A Group of General Dental Practitioners’ Views of Preformed Metal Crowns after Participation in the Hall Technique Clinical Trial: A Mixed-Method Evaluation

Aims

The aims of this study were to investigate and describe the views of a group of general dental practitioners (GDPs) on their use of preformed metal crowns (PMCs) with the conventional method and the Hall Technique. The practitioners involved had previously taken part in a clinical trial of the Hall Technique.

Methods

The dentists’ views were explored using a semi-structured interview (transcribed and analysed using a framework approach) and their use of crowns investigated (for conventional and Hall Technique) using a short questionnaire.

Results

Fourteen out of 17 dentists who participated in the trial were interviewed and completed the questionnaire. Prior to the trial, only three of the GDPs had been using conventional PMCs at all and this was ‘infrequently’. None had been using them routinely. The semi-structured questionnaires revealed three main themes reflecting positively on the GDPs’ experiences with the Hall Technique: its ease of use, its high patient acceptability, and the dentists’ perceived clinical effectiveness of the technique. Thirteen of the 14 GDPs stated that they would continue to use the Hall Technique routinely and only one thought that he would not use it.

Conclusion

Among a small group of GDPs with little experience or training in the use of the Hall Technique, it was perceived to be easy to use routinely, acceptable to patients and effective.

The Hall Technique; a randomized controlled clinical trial of a novel method of managing carious primary molars in general dental practice: acceptability of the technique and outcomes at 23 months

Background

Scotland has high levels of untreated dental caries in primary teeth. The Hall Technique is a simplified method of managing carious primary molars using preformed metal crowns (PMCs) cemented with no local anaesthesia, caries removal or tooth preparation. This study compared the acceptability of the Hall Technique for children, their carers, and dentists, and clinical outcomes for the technique, with conventional restorations.

Methods

General dental practice based, split mouth, randomized controlled trial (132 children, aged 3–10). General dental practitioners (GDPs, n = 17) in Tayside, Scotland (dmft 2.7) placed conventional (Control) restorations in carious primary molars, and Hall Technique PMCs on the contralateral molar (matched clinically and radiographically). Dentists ranked the degree of discomfort they felt the child experienced for each procedure; then children, their carers and dentists stated which technique they preferred. The teeth were followed up clinically and radiographically.

Results

128 conventional restorations were placed on 132 control teeth, and 128 PMCs on 132 intervention teeth. Using a 5 point scale, 118 Hall PMCs (89%) were rated as no apparent discomfort up to mild, not significant; for Control restorations the figure was 103 (78%). Significant, unacceptable discomfort was recorded for two Hall PMCs (1.5%) and six Control restorations (4.5%). 77% of children, 83% of carers and 81% of dentists who expressed a preference, preferred the Hall technique, and this was significant (Chi square, p < 0.0001). There were 124 children (94% of the initial sample) with a minimum follow-up of 23 months. The Hall PMCs outperformed the Control restorations:

a) 'Major' failures (signs and symptoms of irreversible pulpal disease): 19 Control restorations (15%); three Hall PMCs (2%) (P < 0.000);

b) 'Minor' failures (loss of restoration, caries progression): 57 Control restorations (46%); six Hall PMCs (5%) (P < 0.000)

c) Pain: 13 Control restorations (11%); two Hall PMCs (2%) (P = 0.003).

Conclusion

The Hall Technique was preferred to conventional restorations by the majority of children, carers and GDPs. After two years, Hall PMCs showed more favourable outcomes for pulpal health and restoration longevity than conventional restorations. The Hall Technique appears to offer an effective treatment option for carious primary molar teeth.

Trial registration number

Current Controlled Trials ISRCTN47267892 – A randomized controlled trial in primary care of a novel method of using preformed metal crowns to manage decay in primary molar teeth: the Hall technique.

Tapered hollow waveguide for focusing infrared laser beams

A tapered hollow waveguide that can focus a laser beam into a small beam spot is proposed for medical and dental applications. We fabricated hollow tapered optics by using a traveling torch, and the shape was formed as a precise linear taper. For a hollow taper tip with input and output diameters of 700 and 200 microm, respectively, the insertion loss is as small as 0.7 dB in a 10 mm long taper. The hollow taper optic producing a 200 microm spot withstands input energy of 100 mJ. Because a focusing lens is unnecessary at the output end, the laser beam can be introduced into a deep and narrow spot with these tapered optics.

Obtaining an evidence-base for clinical dentistry through clinical trials

Ideally, all clinical practice should be based on the best available evidence; however, in general dental practice even a very routine issue, such as the appropriate management of the carious primary dentition, is hampered by the lack of a sound evidence-base from high quality clinical trials run in general dental practices. Furthermore, the use of the evidence that is available may be confounded by inadequate reporting. This paper reviews the difficulties reported in successfully completing such clinical trials, and reports on the authors' own experiences. Suggestions are made for overcoming the challenge of patient recruitment in randomised controlled clinical trials in primary dental care. These include: regular contact with a principal investigator, who is viewed as a peer; ensuring the relevance of the research topic to the dentists' daily practice; appropriate remuneration; acknowledgement of the contribution made and recognition of the contribution of research activity to continuing professional development. Use of the CONSORT statement to improve planning and reporting of clinical trials is recommended.

Erbium lasers in dentistry

Erbium hard tissue lasers have the capability to prepare enamel, dentin, caries, cementum, and bone in addition to cutting soft tissue. The ability of hard tissue lasers to reduce or eliminate vibrations, the audible whine of drills, microfractures, and some of the discomfort that many patients fear and commonly associate with high-speed handpieces is impressive. In addition, these lasers can be used with a reduced amount of local anesthetic for many procedures. Today, these instruments have evolved from their initial use for all classes of cavity preparations to their ability for removing soft tissue, their usefulness in the disinfection of bacteria within endodontic canals, and most recently, as an alternative to the high speed handpiece for the removal of bone in oral and maxillofacial surgery. In addition, recent research has centered on the value of the erbium family of laser wavelengths in periodontics, including the removal of calculus.

Sequential 3D X-ray microtomographic measurement of enamel and dentine ablation by an Er:YAG laser

OBJECTIVE

To demonstrate the progression of crater growth during repeated sequential application of an Er:YAG laser to enamel and dentine, monitored using X-ray microtomography (XMT).

DESIGN

A single centre study in which laser craters were created in blocks cut from human enamel and/or dentine under standardised and known conditions and then studied using XMT to obtain visualisation and quantification of the effects.

SETTING

University setting, UK, 2001.

MAIN OUTCOME MEASURES

Success was judged by an ability to obtain useful 3D XMT reconstructions of the blocks during crater development, and to make measurements from these data. These measurements were compared with data obtained from similar studies using different measurement techniques.

RESULTS

Time sequences of 2D and 3D images were obtained which demonstrated the progression of laser craters in enamel and dentine. Quantitative measurements from these data enabled values to be derived for the rate of progression of crater depth per unit energy, and the volume of hard tissue removed per unit energy. These values were compared with data derived from other studies and shown to be broadly comparable. However, the present study is unique in that these values were obtained from a series of measurements of the same craters over time.

CONCLUSIONS

3D X-ray microtomography is shown to be a useful tool for quantitative measurements in dental research. For the Er:YAG laser, the relationship of laser crater depth and volume of mineral removed to applied energy was found to be linear.

Immunohistochemical study on pulpal response in rat molars after cavity preparation by Er:YAG laser

While Er:YAG laser systems are in extensive use for caries removal and cavity preparation, the effects of such treatment on pulp tissue remain unclear. This study evaluates these systems using immunohistochemical methods and compares the results with information gained from treatment using conventional burs. Cervical cavities were prepared in the upper first molars of rats, using either an Er:YAG laser or a conventional tungsten-carbide bur. At intervals of 5 min, 6 h, 12 h, 1 d, 3 d and 7 d after cavity preparation, the teeth were processed for immunohistochemical analyses of tissue non-specific alkaline phosphatase, OX6-positive major histocompatibility complex class II antigen-expressing cells and PGP 9.5-immunoreactive nerve fibers. DNA fragmentation was detected by the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) method. Tissue non-specific alkaline phosphatase was observed mainly in the subodontoblastic layer under the cavity lesion, from 5 min, in both groups. The immunoreactivity was more pronounced in the laser group, but by 7 d no significant differences were recognizable. At 12 h, TUNEL-positive cells were detected around the odontoblastic layer in both groups. From 3 d to 7 d, a limited number of positive cells were still visible in the group that underwent standard treatment. Clear similarities in the distribution patterns of OX6-immunopositive cells and PGP 9.5-immunoreactive nerve fibers were also noted. From 12 h to 1 d, OX6-positive cells accumulated along the pulp-dentin border, extending their processes into the dentinal tubules. Numerous bead-like PGP 9.5-immunoreactive nerve fibers were observed under the odontoblastic layer at 7 d. These results demonstrated that there was no appreciable difference in the manner in which pulp tissue responded to treatment with either Er:YAG laser or a conventional drill. This would seem to indicate the usefulness of the Er:YAG laser system in the removal of caries and cavity preparation.