Assessment of the efficiency of dental excavation methods using laser speckle imaging.

This paper introduces a novel application of the laser speckle technique in dentistry, focusing on assessing the efficiency of dental excavation methods used to remove decayed tooth structure. The aim is to evaluate the efficiency of two chemo-mechanical agents and the high-speed drill using the laser speckle technique, which offers objective, non-invasive, and real-time evaluation capabilities. Extracted human primary molars with active occlusal carious lesions were sectioned into three parts, with each part allocated to one of three groups: Group 1 (Brix3000®), Group 2 (Papacarie DUO®), and Group 3 (High-speed drill mechanical caries removal). Caries removal was performed using the designated agent or method for each group. After caries excavation, speckle imaging using a 632.8 nm laser was conducted. Additionally, SEM was used to acquire micro-photographs of the surface morphology of the treated samples. The findings reveal insights into the comparative efficiency of the three dental excavation agents and methods using the laser speckle technique. The speckle parameters extracted from speckle patterns generated by treated teeth provide valuable information for evaluating the performance of the excavation methods. The scanning electron microscopy images also offer detailed visual evidence to support the analysis. This paper demonstrates the potential of the laser speckle technique for assessing the efficiency of dental excavation methods. The objective, non-invasive, and real-time evaluation provided offers advantages over subjective visual assessment and manual measurements.

Marginal quality of ceramic inlays after three different instrumental cavity preparation methods of the proximal boxes.

OBJECTIVES: The marginal quality of ceramic inlays was evaluated after the use of three different instrumental finishing methods in mesio-occluso-distal (mod) cavity boxes in vitro after hydrothermal loading (HTL). MATERIALS AND METHODS: Caries-free human molars were divided into three groups. Mod-cavities were conventionally prepared. Box finishing was performed in every group with rotating (RI), sonic (SI), or ultrasonic (USI) instruments. Surface roughness was examined. Twelve mod-cavities remained untreated. Continuous margin quality was evaluated with scanning electron microscopy (SEM). Ceramic inlays were cemented into cavities. After HTL microleakage, marginal and absolute marginal gaps were examined. All data were analyzed statistically. RESULTS: Significant differences were found, between cavity surface roughness of RI and SI groups, the RI and USI groups, but not between microleakage, marginal, absolute marginal gaps after HTL and in proximal marginal quality. No correlations between microleakage and marginal gaps nor between microleakage and surface roughness were found. CONCLUSION: Mod-cavity proximal box finishing with SI or USI resulted in a higher surface roughness than the use of RI. The type of the finishing method did not influence the marginal quality of ceramic inlays. For the mod-cavity finishing, the use of SI and USI could be an alternative instrumental method to conventional RI methods with a lower risk of iatrogenic damage of the adjacent teeth. CLINICAL RELEVANCE: This study allows the practitioner to better determine the proper indications and limitations of the sonic and ultrasonic instruments for mod-cavity proximal box finishing.

In vitro performance of ultrasound enamel preparation compared with classical bur preparation on pit and fissure sealing.

AIM: Fissure sealants are effective in preventing caries. The aim of this in vitro study was to evaluate the effects of two different enamel surface preparation techniques for pit and fissure sealing. MATERIALS AND METHODS: Sixty extracted sound third molars were used. For each tooth, the mesial half of the occlusal fissures was treated with ultrasound diamond tip T1 mounted on an ultrasonic handpiece, while the distal half with conventional diamond bur. The teeth were randomly divided into 2 groups (n = 30/each). Group 1 samples were stored in distilled water at 4 °C. For group 2 samples, sealing of occlusal fissures was performed according to standard procedures. Bucco-lingual cuts parallel to the long axis of the tooth were made in order to separate the two different types of preparations. The effects of the executed procedures were assessed with SEM. RESULTS: Surfaces prepared with ultrasound system showed the presence of residual debris and appeared more irregular than surfaces prepared with traditional bur system. Furthermore, images showed the presence of cracks on the bottom and on the walls of the ultrasound prepared fissures. CONCLUSION: Conventional bur surface treatment showed a better performance when compared to ultrasound preparation and could probably ensure superior sealant retention.

Effect of Erbium:yttrium aluminum garnet laser on bond strength of a total-etch adhesive system to caries-affected dentin on gingival wall.

PURPOSE: To assess the effect of the erbium:yttrium aluminum garnet (Er:YAG) laser on bond strength of a total-etch adhesive system to the caries-affected dentin on the gingival wall. MATERIALS AND METHODS: Ten human molars with proximal carious lesions were randomly divided into two groups. In the first group, the carious dentin was removed with a bur, whereas in the second group it was removed with the Er:YAG laser. Carious lesions were excavated with one of these two techniques until laser fluorescence values decreased to 15 in the center of the lesions. The teeth were then restored with a total-etch adhesive system (Adper Single Bond 2) and composite resin (Filtek Z250). Five teeth from each group were sectioned to obtain 1 mm2 stick-shaped microtensile specimens from each tooth. Twenty-five specimens were obtained for each group with using this technique. The data were analyzed in independent-samples t-test (α = 0.05). For each removal technique, one sample was analyzed using scanning electron microscopy. RESULTS: No statistically significant differences were found between the bond strength of the Er:YAG laser and the bur-treated groups (P > 0.05). CONCLUSION: The Er:YAG laser treatment did not negatively affect the bonding performance of the total-etch adhesive system to caries-affected dentin on the gingival wall.

Depth and distribution of the cure in a resin-based composite cured in a simulated Class II cavity.

PURPOSE: To examine the effect that a stainless steel (SS) matrix band has on the depth and distribution of cure of a resin-based composite (RBC) in a simulated Class II cavity. METHODS: RBC was cured for 20 seconds in a simulated Class II cavity with and without a SS matrix band, and after 24 hours the specimens were scraped back and ground to expose a vertical central plane where Knoop micro-hardness (KHN) mapping was conducted from 0.05-1.5 mm from the band and in 0.5 mm intervals from the top of the specimens. The effect of different angles of the light guide on the distribution of hardness was also examined. RESULTS: KHN values near the SS matrix band were significantly lower (P < 0.05) than within the bulk of the specimen and were lower than those found without the matrix band. Angles of incidence for the curing light-guide produced changes in the distribution of KHN within the specimens, but particularly near the matrix band, and with a 35° angle of incidence, the depth of cure was significantly different from that of normal incidence of the light.

Dentin Topographic Features following Chemomechanical Caries Removal in Primary Teeth.

AIM: Study the topographic features of dentin after caries removal with a chemomechanical agent (Papacarie) compared with the conventional drilling method. STUDY DESIGN: The sample included 7 exfoliated and extracted primary teeth with carious dentin lesions, not reaching the pulp. Each tooth was sectioned longitudinally through the center of the carious lesions into two halves. The teeth were then divided into two groups according to the method of caries removal. Following caries removal, dentin topography and the cut section were examined using the scanning electron microscope. RESULTS: Papacarie produced an irregular, porous, rough and globular dentin appearance. The dentin surfaces were generally free of smear layer, visible bacteria and the dentinal tubules were opened. The dentin cut surfaces showed patent dentinal tubules with open orifices. The drilling method created a smooth and amorphous surface with a continuous smear layer occluding the dentinal tubules. Numerous bacteria were also observed. The cut dentin surfaces showed patent dentinal tubules with their orifices plugged with smear layer. CONCLUSIONS: Papacarie produced a rough and porous surface with partial or complete removal of the smear layer and opened dentinal tubules, while the drill produced a smooth surface with uniform smear layer occluding the dentinal tubules.

Shear Bond Strength of Self-etching Adhesives to Cavities Prepared by Diamond Bur or Er,Cr:YSGG Laser and Effect of Prior Acid Etching.

PURPOSE: To compare and evaluate shear bond strength of self-etching adhesives bonded to cavities prepared by diamond bur or Er,Cr:YSGG laser and the effect of prior acid etching on shear bond strength. MATERIALS AND METHODS: Ninety-six caries-free human premolars were selected and divided into 2 groups depending on mode of cavity preparation (48 teeth each). Cavities were prepared with Er,Cr:YSGG laser in group 1 and diamond burs in an air-turbine handpiece in group 2. Groups 1 and 2 were further subdivided into three subgroups of 8 teeth each, which were bonded with sixth- or seventh-generation adhesives with or without prior acid etching, followed by restoration of all samples with APX Flow. These samples were subjected to shear bond strength testing. In addition, the surface morphology of 24 samples each from groups 1 and 2 was evaluated using SEM. Data were analyzed using the Shapiro-Wilk test, one- and two-way ANOVA, the t-test, and the least significant difference test, which showed that the data were normally distributed (p > 0.05). RESULTS: The shear bond strength of adhesives in cavities prepared by Er,Cr:YSGG laser was significantly higher than in diamond bur-prepared cavities (p < 0.05). SEM analysis showed a smear-layer-free anfractuous surface on laser-ablated teeth, in contrast to conventional bur-prepared teeth. CONCLUSIONS: The Er,Cr:YSGG laser-ablated surface proved to be more receptive for adhesion than those prepared by diamond bur irrespective of the bonding agent used. Seventh-generation adhesives yielded higher shear bond strength than did sixth-generation adhesives. Prior acid etching decreased the shear bond strength of self-etching adhesives.

Comparison of Carisolv system vs traditional rotating instruments for caries removal in the primary dentition: A systematic review and meta-analysis.

OBJECTIVE: The purpose of this systematic review and meta-analysis was to evaluate the reliability of the Carisolv system with respect to drilling regarding the full removal of decayed hard tissues in primary dentition. A systematic review of the literature was conducted to identify controlled trails, randomized controlled trials and clinical trials that compared the Carisolv system to the traditional mechanical caries removal in the primary dentition. MATERIALS AND METHODS: The main relevant databases were searched: MEDLINE via PUBMED, Web of Science and SCOPUS. Complete caries removal, length of working time and need of local anesthesia were the outcomes evaluated. RESULTS: A total of 195 studies were identified and complete analysis of 28 studies was performed; finally, 10 papers were included. The trials included involved a total of 348 patients for 532 treated teeth. There was no significant difference in terms of clinical efficacy between the Carisolv and the rotary instrument (z = 0.68, p = 0.50), whereas the treatment with Carisolv was significantly longer in terms of time with respect to the rotary instruments (z = 10.49, p < 0.01). The chemo mechanical technique reduces the need for local anesthesia, with a difference between two types of treatment near to statistical significance (z = 1.91 p = 0.06). CONCLUSIONS: This systematic review indicates that the clinical efficacy of chemo-mechanical removal with Carisolv seems as reliable as the rotary instruments. However, the results should be interpreted cautiously due to the heterogeneity among study designs and to the shortage of available data. Further large-scale, well-designed randomized controlled trials are needed.

Preparing and Restoring Composite Resin Restorations. The Advantage of High Magnification Loupes or the Dental Surgical Operating Microscope.

Use of magnification, such as 6x to 8x binocular surgical loupes or the surgical operating microscope, combined with co-axial illumination, may facilitate the creation of stable composite resin restorations that are less likely to develop caries, cracks or margin stains over years of service. Microscopes facilitate observation of clinically relevant microscopic visual details, such as microscopic amounts of demineralization or caries at preparation margins; microscopic areas of soft, decayed tooth structure; microscopic amounts of moisture contamination of the preparation during bonding; or microscopic marginal gaps in the composite. Preventing microscope-level errors in composite fabrication can result in a composite restoration that, at initial placement, appears perfect when viewed under 6x to 8x magnification and which also is free of secondary caries, marginal staining or cracks at multi-year follow-up visits.

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

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

Influence of long-term water storage and thermocycling on shear bond strength of glass-ionomer cement to Er:YAG laser-prepared dentin.

PURPOSE: To evaluate the influence of long-term water storage and thermocycling on the shear bond strength of a glass-ionomer cement to Er:YAG-irradiated and bur-prepared dentin. MATERIALS AND METHODS: Fifteen bovine incisors were selected and the roots removed. Crowns were sectioned into four pieces, resulting in 60 samples that were individually embedded in polyester resin (n = 15) and ground to plane the enamel and expose the dentin. The bonding site was delimited and samples were randomly assigned according to the method of cavity preparation: Er:YAG laser (250 mJ/4 Hz) or high-speed handpiece (diamond bur #2096). Samples were fixed to a metallic device, where glass-ionomer cement (GIC) cylinders were prepared. Subsequently, they were subdivided according to the duration of water storage (WS) and number of thermocycles (TCs) - 24 h WS/no TCs and 6 months WS/12,000 TCs - and subjected to a shear bond strength test (500 N at 0.5 mm/min). RESULTS: The duration of water storage and number of thermocycles tested had no statistically significant effect on the shear bond strength to laser-irradiated dentin (p > 0.05). For bur-prepared substrate, the long-term degradation process promoted a decrease in shear bond strength values (p < 0.05). CONCLUSION: Long-term water storage and thermocycling did not affect shear bond strength of glass-ionomer cement bonded to Er:YAG laser-prepared dentin.

Effect of chemomechanical caries removal on bonding of self-etching adhesives to caries-affected dentin.

PURPOSE: To evaluate the effect of enzyme-based (Papacárie) and sodium-hypochlorite-based (Carisolv) chemomechanical caries removal methods on bonding of self-etching adhesives to caries-affected dentin, in comparison to the standard rotary-instrument caries removal method. MATERIALS AND METHODS: Seventy-eight carious permanent molars exhibiting frank cavitation into dentin were used. Forty-eight teeth were randomly divided into three groups, according to the caries excavation methods: (i) Papacárie, (ii) Carisolv and (iii) a round steel bur. After caries removal, each group was subdivided into two groups for two-step (Clearfil SE Bond) or one-step (Clearfil S3 Bond) self-etching adhesive application and resin composite buildups. Bonded specimens were sectioned into beams for microtensile bond strength testing. Bond strength data were analyzed using three-way ANOVA and Tukey's test. For interfacial nanoleakage evaluation using a field-emission scanning electron microscope, caries was similarly removed from the remaining thirty carious molars, bonding was performed as for bond strength testing, and the teeth were sectioned. RESULTS: RESULTS of three-way ANOVA revealed that bond strength was significantly affected by "adhesive" (p<0.001) and "dentin" (p<0.001), but not "caries excavation methods" (p>0.05). The bond strength of the two-step self-etching adhesive was significantly higher than that of the one-step self-etching adhesive (p<0.001). Conversely, the bond strength of self-etching adhesives to sound dentin was significantly higher than to residual caries-affected dentin (p<0.001). Greater silver penetration was observed in the bonded interfaces of residual caries-affected dentin and in interfaces bonded with the one-step self-etching adhesive vs those bonded with the two-step self-etching adhesive. CONCLUSION: Chemomechanical caries removal did not affect the bonding of self-etching adhesives to caries-affected dentin as compared to caries excavation with rotary instruments.

MicroCT-based comparison between fluorescence-aided caries excavation and conventional excavation.

PURPOSE: To evaluate and compare the use of micro-computed tomography (microCT) to investigate the mineral concentration of the treated dentin surface after caries removal with fluorescence-aided caries excavation (FACE) and conventional excavation. METHODS: 20 extracted human teeth with dentin caries were bisected through the lesion center into two halves which were distributed to a FACE and a conventional excavation group. Tungsten-carbide round burs were used for both groups. Each specimen was investigated with microCT after excavation. The obtained images of all the specimens were evaluated using Image J. Based on the grey values, the linear attenuation coefficients were calculated. Four resin-embedded solid hydroxyapatite phantoms with the gradually increased mineral concentration were used to obtain a calibration curve and equation. Finally, the mineral concentration values of the superficial dentin of each specimen after removal and sound dentin were calculated. The data were compared with the Student's t-test. RESULTS: The statistical results showed that the linear attenuation coefficient (LAC) of the treated surface was significantly lower (P < 0.0001) in the FACE group with a mean value of 2.13 +/- 0.33 cm9-1). The value of the conventional excavation group was 2.98 +/- 0.19 cm(-1). The LAC of sound dentin was 3.89 +/- 0.10 cm(-1). By using the calibration equation, the calculated mineral concentration of the superficial dentin after caries removal were 0.68 +/- 0.14 g/cm3 in the FACE group and 1.05 +/- 0.08 g/cm3 in the conventional excavation group. The mineral concentration of sound dentin was 1.44 +/- 0.04 g/cm3. The mineral concentration of the superficial dentin after caries removal in the FACE group was about 47% of that of sound dentin, while the value in the conventional excavation group was approximately 73% of that of sound dentin. Under the conditions of this in vitro study, the results of the microCT evaluation may imply that FACE was more conservative than conventional excavation.

Microhardness evaluation of enamel adjacent to an improved GIC sealant after different enamel pre-treatment procedures.

AIM: This in vitro study was carried out to evaluate the microhardness of enamel adjacent to a glass ionomer cement (GIC) with high fluoride content used as a sealant (Fuji Triage, GC Corp., Japan) after laser, bur or air abrasion treatment procedures. STUDY DESIGN: 200 freshly extracted non-carious human molars were divided into 10 experimental groups according to the enamel pre-treatment method: A air abrasion (Mach 4.1 Kreativ Inc., USA); AP, Air abrasion + conditioning with 20% polyacrylic acid (GC cavity conditioner); L, Er,Cr:YSGG laser application (Waterlase, Biolase Technology, Inc., San Clemente, USA); LP, Er,Cr:YSGG laser application and fissure conditioning; B, ameloplasty carried out with a diamond bur especially designed for preparing fissures (Komet #8833); BP, ameloplasty + fissure conditioning; P, application of 20% polyacrylic acid and all fissures sealed with GIC; C, no fissure treatment, the material was applied directly to the fissures (control); R, application of 37% orthophosphoric acid and fissures sealed with a resin-based sealant (Fissurit; Voco, Germany) (control); N, no treatment (control). Half of each group of teeth were left in artificial saliva for one month and the rest for three months. The teeth were then sectioned and microhardness was measured using a Vickers test apparatus. Kruskal-Wallis, Mann-Whitney U and Dunn's multiple comparison tests were carried out (5% significance). RESULTS: After one month results regarding hardness at the base and lateral walls of fissures were significantly higher in groups A, AP, L, LP, B, BP, P and C than in groups R and N (p<0.01), but no difference was seen between the treatment procedures. The results after three months produced similar findings with evenly increased values for all groups. CONCLUSION: The results of this study showed that the tested GIC with a higher fluoride content seemed to improve the enamel hardness of the fissure enamel and could be regarded as an alternative material in cases where resin sealant applications are questionable.

Chemo-mechanical caries removal with Papacarie™: case series with 84 reports and 12 months of follow-up.

AIM: The aim of the present study was to determine the success rate after 12 months of follow-up in a series of cases in which chemo-mechanical caries removal (CMCR) was performed with Papacarie(TM), followed by restoration with glass ionomer cement. BACKGROUND: The development of conservative techniques for carious tissue removal and improvements in dental restoration materials have allowed better preservation of dental structures in the treatment of decayed teeth. Chemo-mechanical caries removal (CMCR) is a conservative atraumatic treatment option. Papacarie(TM) is a papain-based material developed to act only on the carious dentin, allowing its easy removal with a blunt curette. CASE REPORT: The study involved a total of 84 deciduous posterior teeth with occlusal dentinal caries. Only teeth without risk of pulp exposure were studied. After a period of 12 months, the restorations were evaluated based on criteria employed in previous studies. The radiographic evaluation revealed resorption and calcification of the affected teeth. The data were submitted to descriptive statistical analysis with the aid of the XLSTAT program. The success rate was 88.1% and 98.8% based on the clinical and radiographic evaluations, respectively. The difference between the success and failure rates was statistically significant (p < 0.0001). CONCLUSION: Papacarie(TM) is an effective product for CMCR on occlusal dentinal tissue in deciduous teeth, demonstrating a high clinical and radiographic success rate after 12 months of follow-up.

Evaluation of dentin features in teeth after caries removal by three techniques (chemomechanical, mechanical with a smart bur, and air-abrasion): an in vitro study.

Background: Different methods for removing dental carious lesions exist, including conventional rotary caries removal and new advanced technology like polymer-based burs, chemomechanical agents, air abrasion, and laser. Objectives: This study shows the differences in features of dentin (smear layer, patency of dentinal tubules, surface irregularities, intertubular micro porosities, and exposed dentinal tubules) among different types of caries removal techniques. Materials and Methods: An in vitro study was done on 60 primary molars with occlusal class I active caries. Teeth were divided into three groups according to a method of caries removal (G1: chemomechanical, G2: mechanical with a smart bur, and G3: air-abrasion). After complete caries excavation, the teeth were examined under a scanning electronic microscope (SEM) with the power of magnification 4,000x and 8,000x to show the morphological dentinal features with SEM microphotographs. Data obtained was analyzed using the SPSS program where Fisher exact, Kruskal-Wallis and multiple Wilcoxon sum rank tests were used. The level of significance is when the p-value is less than 0.05. Results: Generally, SEM showed the highest ratio of score 1 of smear layer presence, surface irregularities, and microporosity in all groups in both magnifications. The patency of tubules showed the highest ratio of score 1 in G1, scores 2 in both G2 and G3 in magnification 4,000x, while 8,000x there was the highest ratio of its score 1 in G1 and G2 while the G3 has score 2 as the highest score. The exposed dentinal tubules showed the highest ratio in G1 in score 3, in G2 in score 2, and in G3 in score 1 in magnification 4,000x, while 8,000x there was the highest ratio of its score 2 in both G1 and G3 while the G3 has highest score 1. The study with magnification 4,000x showed a significant difference (S) among three groups in exposed dentinal tubules with a p-value (0.012), and there was S between chemomechanical and smart, chemomechanical and air-abrasions groups with a p-value (0.041, 0.001 subsequentially). Other dentin features showed non-significant differences (NS) among or between groups in both magnifications (4,000x, 8,000x). Conclusions: All groups were effective in removing caries and can successfully treat young, scared or stressed patients. All methods of caries removal produce clinically parametric changes in the residual dentin.

Evaluation of Papacarie®, Carie-Care™, BRIX3000™ and conventional hand instrumentation for caries removal in primary teeth: a randomized control study.

In the current odontological era, carious lesions are removed while tooth tissue is preserved. Most of these ideals are met by chemomechanical caries removal (CMCR) methods, which are easy and comfortable to use, differentiate and eliminate infected tissues, minimize pressure, vibration and heat, and are cost-effective. This study examines the efficacy of commercially available CMCR agents, namely Papacarie®, Carie-Care™ and BRIX3000™, and a conventional hand instrumentation method for caries removal in deciduous molars in terms of time consumption, ease of application, and pain perception. For this randomized clinical trial, 120 children aged 4 to 9 years were selected and randomly allocated to four groups of 30 patients each. Time consumption, ease of application, and pain perception were evaluated at three intervals: pre-, during- and post-caries removal, using Wong-Baker FACES (WBF) Pain Rating Scale and the Face, Legs, Activity, Cry, Consolability (FLACC) scale. The results showed that among the compared materials and conventional hand instrumentation technique, Carie-Care™ was statistically found to be the least time-consuming with a p-value of 0.019, have the least pain perception with a p-value of 0.02, and was clinically the best with respect to manipulation and handling. While all three CMCR agents aid in the removal of carious tissue, Carie-Care™ was the most effective based on time consumption, pain perception and simplicity of administration.

Attitudes and behaviour regarding deep dentin caries removal: a survey among German dentists.

Incomplete removal of deep caries has been shown to reduce the risks of pulp exposure and postoperative pulpal complications. It is therefore of interest whether dentists perform one- or two-step incomplete excavation, and which criteria and methods they use to assess and provide removal of deep caries. This study investigated the attitudes and behaviour of dentists in northern Germany using a new, validated questionnaire. The survey included 2,346 practitioners, 821 (35%) of whom responded. Demographic and sensitivity analysis did not indicate selection bias. 50% of dentists considered only complete excavation, even if pulp exposure was likely. If caries was to be removed incompletely, 77% considered two-step excavation. Hardness was the most important criterion to assess excavation. To treat an exposed pulp, 75% of dentists considered direct capping, 70% refused incomplete excavation fearing caries progression or pulp damage, and 59% reported to prefer more invasive treatment to facilitate restoration longevity. Over 50% recognised an influence of professional regulations on their treatment decisions. There was a moderate correlation between attitudes and behaviour of dentists, with dentists who suspected residual caries to be harmful rejecting incomplete excavation and vice versa. Cluster analysis identified two groups of dentists with opposite attitudes and behaviour, independently from dentist's age or gender. In conclusion, the majority of surveyed dentists was sceptical about leaving caries during excavation and does not practice incomplete caries removal. Therefore, benefits of partial excavation should be highlighted in under- and postgraduate education and regulatory incentives modified to promote minimally invasive techniques.

Precise ablation of dental hard tissues with ultra-short pulsed lasers. Preliminary exploratory investigation on adequate laser parameters.

This study aimed to evaluate the possibility of introducing ultra-short pulsed lasers (USPL) in restorative dentistry by maintaining the well-known benefits of lasers for caries removal, but also overcoming disadvantages, such as thermal damage of irradiated substrate. USPL ablation of dental hard tissues was investigated in two phases. Phase 1--different wavelengths (355, 532, 1,045, and 1,064 nm), pulse durations (picoseconds and femtoseconds) and irradiation parameters (scanning speed, output power, and pulse repetition rate) were assessed for enamel and dentin. Ablation rate was determined, and the temperature increase measured in real time. Phase 2--the most favorable laser parameters were evaluated to correlate temperature increase to ablation rate and ablation efficiency. The influence of cooling methods (air, air-water spray) on ablation process was further analyzed. All parameters tested provided precise and selective tissue ablation. For all lasers, faster scanning speeds resulted in better interaction and reduced temperature increase. The most adequate results were observed for the 1064-nm ps-laser and the 1045-nm fs-laser. Forced cooling caused moderate changes in temperature increase, but reduced ablation, being considered unnecessary during irradiation with USPL. For dentin, the correlation between temperature increase and ablation efficiency was satisfactory for both pulse durations, while for enamel, the best correlation was observed for fs-laser, independently of the power used. USPL may be suitable for cavity preparation in dentin and enamel, since effective ablation and low temperature increase were observed. If adequate laser parameters are selected, this technique seems to be promising for promoting the laser-assisted, minimally invasive approach.

Evaluation of micromorphological changes in tooth enamel after mechanical and ultrafast laser preparation of surface cavities.

The aim of this in vitro study was to evaluate the morphological changes that occur in tooth enamel after mechanical instrumentation and after femtosecond laser irradiation with different parameters via light and scanning electron microscopy (SEM). Twelve totally impacted third molars were collected and sectioned to provide several cut surfaces. These surfaces were exposed to infrared (λ = 795 nm, 120 fs, 1-kHz repetition rate, maximum mean power 1 W) laser pulses and machined by means of a conventional mechanical technique. Two very different geometrical patterns were performed with femtosecond laser pulses: shallow rectangular cavities and deep cylindrical ones. The results of both machining procedures were examined using light and scanning electron microscopy. The SEM images show the femtosecond laser ability to produce high-precision cavities in tooth enamel. No signs of collateral damage, burning, melting, or cracks were observed despite the far different laser pulse energies used (ranging from 7 to 400 µJ), unlike what is seen with conventional mechanical techniques. The femtosecond laser has the potential to become an optimal tool for the treatment of dental decay and as an alternative to the conventional drill to reduce mechanical damage during removal of the hard dental tissue.