Cross sectional: use of coolant for high-speed tooth preparation: a survey of pediatric dentist members of the American Academy of Pediatric Dentistry

PURPOSE

To report the findings of a survey to determine the educational experiences, opinions and clinical practices relative to the use of coolant during cavity preparation of pediatric dentist members of the American Academy of Pediatric Dentistry (AAPD) and to determine whether teaching policies influenced the type of coolant used in private practice.

METHODS

Four thousand fifty surveys were emailed to AAPD members and included questions regarding demographics and predoctoral, graduate, and current practice policies for the use of dry cutting.

RESULTS

Returned survey numbered 1730 for a response rate of 43%. Fifteen percent were taught the concept of dry cutting in their predoctoral programs and 34% in their specialty, programs. Sixty percent never or rarely prepare teeth without water coolant. Slightly more than 40% prepared teeth with air coolant alone. Patient behavior (25%) and sedation (21%) were reported as determining factors for cutting dry. Thirty-one percent of private practice clinicians and 34% of part time academics use dry cutting, while only 15% of full time academicians use the technique (P<0.0001).

CONCLUSIONS

Respondents tend to use the technique they were taught during their residency. Use of dry cutting was more likely to be utilized during sedations or general anesthesia to avoid airway compromise.

Learn-a-prep II as a predictor of psychomotor performance in a restorative dentistry course

This investigation assessed whether early student performance with a dental handpiece on a didactic training aid known as the Learn-A-Prep II (LAP II) was predictive of performance on subsequent practical examinations in a preclinical restorative dentistry course. Eighty-one first-year students were given initial handpiece training and formative feedback using the LAP II and were then instructed to independently prepare four LAP II patterns within the pattern lines and at a specified depth. Performance on the LAP II was compared with the summative assessment on two subsequent amalgam preparation practical examinations given at the middle (Class II) and end (Complex) of the course. Pattern preparation within the lines did not significantly improve the likelihood of receiving an A or B on the Class II practical (p=0.53) or on the Complex practical (p=0.37). Students who had an acceptable depth on the LAP II were 3.73 times more likely to receive an A or B on the Class II practical than those students who did not have acceptable depth (p=0.03). Performance at an acceptable depth did not significantly improve the likelihood of receiving an A or B on the Complex practical (p=0.15). The LAP II may aid in identification of students who would benefit from early intervention with additional focused instruction.

[SEM comparative analysis of the composite diacrylic resin-enamel interface in laser and bur prepared cavities]

The aim of this study was to demonstrate that the size of the hybrid layer (HL) in the prepared enamel mechanic (M) and kinetic (K) with laser (WaterlaseMDBiolase), evaluated by scanning electron microscopy (SEM) restored with two types of resin composite is different.

MATERIAL AND METHOD

The study was realized in vitro on a sample of 40 extracted human premolar and molars teeth for orthodontic or periodontal reasons. The teeth were divided at random into equal four groups (Gr). There has been Class I cavities with a depth of 2 mm (M) at high and low speed with cylindrical diamond No.1 and globular carbide and (K) peaks MZ6-5, 5W+20 Hz 30% water 60% air. The teeth were restored using 3M Schotchbond Etch, 3M Single Bond Dental Adhesive System: Gr. 1: (K)(n = 10)-3M Filtekflow; Gr.2 : (K)(n = 10)3M FiltekZ250; Gr.3: (M)(n = 10)3M Filtekflow; Gr.4: (M)(n = 10)3M FiltekZ250. The materials were placed in a single layer and photoactivate source LED SmartLite (Dentsply), termocycling 500 cycles (5 degrees-55 degrees), stored (48h), cut lengthwise (diamond), polished, conditioned (H3PO4-37% -5s) analyzed by SEM (JEOLJSM 6390), SPSS 13.00 statistically analyzed (ANOVA, p = 0.05).

RESULTS

Analysis of the (HL) has highlighted differences between groups p = 0.05 average size (HL) being Gr.1;20.80 (+/- 0.72)microm, Gr.2;4.034 (+/- 0.0076)microm, Gr.3, 14.13 (+/- 0.63)microm, Gr.4, 1,43 (+/- 0.16)microm. Value size (HL) was influenced by the cavity preparation method for samples prepared by laser p = 0,005 in terms of size and in advantage of mechanical preparations in terms of quality (HL). Also the value of (HL) size was influenced by the type of material used in advance Gr.2 p = 0.0017.

CONCLUSIONS

The sealing of cavity depends more on the creep of materials and less on the type of preparation. Permission was obtained from a institutional ethical committee of "Gr.T. Popa" University of Medicine and Pharmacy Iaşi and that subjects gave written, informed consent).

Marginal microleakage of alternative restorative treatment and conventional glass ionomer restorations in extracted primary molars

PURPOSE

The objective of this study was to compare the marginal leakage of cervical glass ionomer restorations made using alternative restorative treatment (ART) and conventional restoration techniques.

METHODS

Twenty primary molars with Class V carious dentin on the buccal surfaces were prepared using ART, and a second set of 20 noncarious molars had Class V preparations made with a high-speed handpiece. The occlusal margin was located in enamel and the gingival margin in dentin/cementum. All teeth were restored with high-density glass ionomer cement (GIC; Fuji IXgp) according to manufacturers' instructions, thermally stressed for 300 cycles, and stained with methylene blue. Samples were sectioned and evaluated for microleakage.

RESULTS

One-way analysis of variance revealed no statistically significant difference between leakage at margins of ART and conventional restorations. (P=.92) There was no significant difference between leakage at the enamel and dentin margins.

CONCLUSIONS

Alternative restorative treatment with high-density glass ionomer cement provides enamel and dentin margins that show marginal leakage comparable to conventionally restored primary teeth. These results show the potential of ART in conjunction with high-density GIC in providing treatment for children and adolescents in situations where traditional cavity preparation and restoration is not possible.

In vitro microleakage of composite restorations prepared by Er:YAG/Er,Cr:YSGG lasers and conventional drills associated with two adhesive systems

PURPOSE

The objective of this in vitro study was to compare the degree of microleakage of composite restorations performed by lasers and conventional drills associated with two adhesive systems.

MATERIALS AND METHODS

Sixty bovine teeth were divided into 6 groups (n = 10). The preparations were performed in groups 1 and 2 with a high-speed drill (HD), in groups 3 and 5 with Er:YAG laser, and in groups 4 and 6 with Er,Cr:YSGG laser. The specimens were restored with resin composite associated with an etch-and-rinse two-step adhesive system (Single Bond 2 [SB]) (groups 1, 3, 4) and a self-etching adhesive (One-Up Bond F [OB]) (groups 2, 5, 6). After storage, the specimens were polished, thermocycled, immersed in 50% silver nitrate tracer solution, and then sectioned longitudinally. The specimens were placed under a stereomicroscope (25X) and digital images were obtained. These were evaluated by three blinded evaluators who assigned a microleakage score (0 to 3). The original data were submitted to Kruskal-Wallis and Mann-Whitney statistical tests.

RESULTS

The occlusal/enamel margins demonstrated no differences in microleakage for all treatments (p > 0.05). The gingival/dentin margins presented similar microleakage in cavities prepared with Er:YAG, Er,Cr:YSGG, and HD using the etch-and-rinse two-step adhesive system (SB) (p > 0.05); otherwise, both Er:YAG and Er,Cr:YSGG lasers demonstrated lower microleakage scores with OB than SB adhesive (p < 0.05).

CONCLUSION

The microleakage score at gingival margins is dependent on the interaction of the hard tissue removal tool and the adhesive system used. The self-etching adhesive system had a lower microleakage score at dentin margins for cavities prepared with Er:YAG and Er,Cr:YSGG than the etch-and-rinse two-step adhesive system.

Atraumatic tooth preparation

One of the tenets of operative dentistry is to maintain the health and vitality of teeth whenever possible. Methods of tooth preparation can adversely affect the tooth structure and the pulp. This paper will review the research on methods and devices used to prepare teeth, the possible sequelae of tooth preparation, and the best methods that can be recommended from the research to maintain tooth vitality and marginal integrity.

An in vitro comparison of marginal microleakage of alternative restorative treatment and conventional glass ionomer restorations in extracted permanent molars

PURPOSE

The objective of this study was to compare the marginal leakage of cervical restorations made using alternative restorative treatment (ART) and conventional glass ionomer restorations.

METHODS

Sixteen permanent maxillary and mandibular first and second molars extracted for periodontal reasons with Class V carious dentin on the buccal surfaces were prepared using ART while a second set of 29 noncarious molars had Class V preparations made with a high-speed handpiece. The occlusal margin was located in the enamel, and the gingival margin was located in the dentin/cementum. All teeth were restored with glass ionomer cement (GIC). The teeth were thermally stressed for 300 cycles and stained with methylene blue. Samples were sectioned and evaluated for microleakage.

RESULTS

One-way analysis of variance on ranks revealed no significant difference in leakage at both the dentin and enamel margins between the conventional and ART groups. The microleakage at the dentin margin, however, was significantly greater (P < .001) than at the enamel margins in the conventional group.

CONCLUSION

Alternative restorative treatment with GIC provides enamel and dentin margins that show comparable marginal leakage to conventionally restored permanent teeth. For the conventional restorations, leakage at the dentin margins occurs to a significantly higher extent than at the enamel margins.

In vitro effectiveness of a chemo-mechanical method for caries removal

AIM

The aim of the study was to assess the efficacy of chemo-mechanical method for caries removal based on histological analysis and scanning electron microscopy of dentine samples.

METHODS

Forty-five freshly extracted human deciduous and permanent teeth with dentinal caries were used in this in vitro study. The teeth were allocated to two different technique groups. Chemo- mechanical caries removal using Carisolv was performed in 30 teeth and in 15 teeth caries was removed using conventional rotary instruments. The caries status of dentine was judged according to clinical criteria (probing and visual inspection). After caries removal had been completed, teeth were sectioned through the prepared cavities and the two halves of each tooth were processed for light microscopy and scanning electron microscopy. Light microscope was used to examine the specimens for the presence of bacteria in dentine tubules. Scanning electron microscope was used to determine surface characteristics of the cavity floor after caries removal.

RESULTS

All examined dentine surfaces were clinically caries free. Regarding the presence of bacteria, 53% of chemo- mechanically prepared teeth and 87% of conventionally prepared teeth were bacteria-free (p>0.05). Efficacy of both methods was confirmed using scanning electron microscope, but different dentine topography was recorded after chemo-mechanical and conventional caries removal.

CONCLUSION

Based on histological and scanning electron microscope analyses it could be concluded that this chemo-mechanical method is efficient in the removal of carious dentine.

Computerized navigation surgery for the safe placement of palatal implants

Palatal endosseous implants are increasingly recognized as an important alternative for achieving maximal intraoral orthodontic anchorage; however, their safe surgical placement is a matter of concern. Available palatal bone is frequently limited, and erroneous drilling can damage adjacent structures. Computerized navigation surgery is an advanced surgical modality in which the surgical drill is accurately tracked and animated in real time on the radiological image of the surgical site. In implant dentistry, this surgical modality allows accurate navigation of the implant drilling procedure and increases safety and accuracy, compared with conventional dental implant surgery. This article outlines the principles of computerized navigation surgery and describes its application for the placement of palatal orthodontic implants. The merits of this approach are particularly important for patients with limited palatal bone when implant placement requires high surgical precision.

Chemomechanical caries removal in children: efficacy and efficiency

BACKGROUND

The authors investigated the effectiveness of chemomechanical caries removal (CMCR) compared with the traditional method (TM) of caries removal using a round bur when treating dentinal-depth occlusal lesions with minimal enamel access in primary molars. The authors also compare CMCR with TM to determine if it had a higher efficacy and could be used more frequently without the subject's having to undergo local anesthesia.

METHODS

The authors collected data from 50 children during operative appointments at which caries was removed using one of the two methods.

RESULTS

Complete caries removal within 15 minutes was achieved in only 57.7 percent of the CMCR-treated teeth. In 42.3 percent of these teeth, residual caries was removed using TM. CMCR was almost eight times more time-consuming than was TM when used to excavate dentinal-depth occlusal lesions with minimal cavitation. There was no significant difference between CMCR and TM in the number of subjects who needed to undergo local anesthesia.

CONCLUSIONS

The authors found no direct clinical advantage in using CMCR over using TM for treating occlusal dentinal lesions with minimal cavitation in pediatric patients.

Temperature changes in the deciduous pulp chamber during cavity preparation with the Er:YAG laser

PURPOSE

The purpose of this in vitro study was to evaluate the temperature changes in the pulp chambers of deciduous molars during cavity preparation with an Er:YAG (erbium substituted: yttrium aluminium garnet) laser.

METHODS

Two cavities were prepared in 14 maxillary deciduous molars: one with the Er:YAG laser and other with a diamond bur using a high-speed handpiece (control), providing 4 groups with 7 cavities each. The laser treatment was applied for 30 seconds (group 1) and 60 seconds (group 3). The internal pulp temperature was recorded during preparation procedures with a thermocouple, and temperature changes were calculated by the difference between the maximum and initial temperature.

RESULTS

There were significant differences (P<.01) between Er:YAG laser irradiation for 60 seconds and 30 seconds and the 2 high-speed drilling groups, which were similar. The Er:YAG laser used for 60 seconds provided the highest temperature alteration (4.01 degrees C).

CONCLUSION

Er:YAG laser irradiation increased the temperature of the deciduous teeth compared to the high-speed drilling treatment. The temperature increments, however, remained below the critical value (5.5 degrees C).

Microleakage study of different adhesive systems in Class V cavities prepared by Er,Cr:YSGG laser and bur preparation

This study sought to compare the microleakage of composite resin restorations using two different dentin adhesive systems and two different modes of cavity preparation: a high-speed handpiece and an Er,Cr:YSGG laser. Twenty-five caries-free permanent human premolars were assigned randomly into five groups of five. A high-speed handpiece was used to prepare Class V cavities on the buccal and lingual surfaces of 10 randomly selected teeth. Class V cavities were cut on the buccal and lingual surfaces of the remaining 15 teeth using the Er,Cr:YSGG laser system. Fifty cavities were prepared with enamel and dentin margins 1.0 mm below the cemento-enamel junction and assigned into five groups: I, II, and III by the Er,Cr:YSGG laser and IV and V by the high-speed handpiece. In all groups, the differences between gingival and occlusal leakage scores were statistically significant (p < 0.05). The occlusal and gingival scores of groups I and IV demonstrated statistically significant differences (p < 0.05). The lased group with additional acid etching revealed less microleakage than groups III and IV (p < 0.05). Both self-etch and total-etch adhesive systems demonstrated acceptable microleakage scores when used on Er,Cr:YSGG laser-prepared cavities; however, additional acid etching after Er,Cr:YSGG laser preparation is recommended.

SEM and profilometric evaluation of enamel surface after air rotor stripping--an in vitro study

The aim of the study was to evaluate roughness of the enamel surface after Air Rotor Stripping (ARS). Thirty interproximal surfaces of human premolars were used as the biological material. Research was conducted using a contact profilometer and a scanning electron microscope (SEM). Sets of 3D parameters and topographical maps of enamel surface before and after ARS treatment were used to define roughness of the surfaces. SEM images of stripped surfaces were taken with microscopic magnification of 100x and 1000x. The data revealed a general roughness of enamel arising after ARS procedure. Summarized values of chosen parameters increased after ARS procedure compared to the values of untreated enamel. Topographical maps showed areas of both well polished and badly polished enamel. In conclusion, comparison of the mean values of the measured parameters of ARS treated enamel surfaces indicated that roughness of the enamel arises after ARS, but it must be emphasized that on every evaluated surface well polished areas were also present. Moreover, the well polished areas were smoother than those on the untreated enamel surfaces. Contact fluoridation and improved oral hygiene after ARS appear to be necessary because of the presence of areas of increased roughness on evaluated surfaces.

Heat generated by residual adhesive removal after debonding of brackets

AIM

To measure the rise in temperature during mechanical removal of residual adhesive after debonding of brackets in vitro.

METHODS

Different carbide burs on a high-speed handpiece were tested. Acrylic on the buccal surfaces of recently extracted human maxillary incisors was removed using 3 types of carbide burs (6-, 12-, 40-fluted) with a varying number of windings relative to the long axis of the shaft. The temperature was measured using a thermocouple probe in the pulp chamber of the extracted teeth.

RESULTS

The highest mean rise in temperature was measured using a 6-fluted bur (+9.4 degrees C, P < .001), followed by the 12-fluted bur (+6.5 degrees C, P <.001). The lowest rise in temperature (+1.2 degrees C, not significant) was seen with a 40-fluted bur. After 3 to 8 seconds of continuous grinding, the rise in temperature seems to slow down.

CONCLUSION

The removal of residual adhesive after debonding is best performed with fine burs. If 6-fluted burs are used, a pause after 5 to 10 seconds of continuous grinding is recommended, especially in the mandibular anterior area.

The effect of wear on ultrasonic scaler tip displacement amplitude

AIM

During clinical usage, scaler tips may become worn and reduced in length. It is unknown what effect wear has on the magnitude of scaler tip vibrations when they are utilized under typical clinical loads. The aim of this investigation was to assess the effect of simulated wear on ultrasonic scaler tip displacement amplitude, using a scanning laser vibrometer.

MATERIALS AND METHODS

A Cavitron SPS (Dentsply) ultrasonic generator and three scaler insert designs (FSI-100, FSI-1000 and FSI-SLI-10S) were selected for the investigation. Tip vibration displacement amplitude was assessed unloaded and then contacting against tooth surfaces with loads of 0.5 and 1.0 N. Tips were then ground down by 1 mm and then 2 mm and scans were repeated.

RESULTS

For all tips, load and length were found to be significant variables (p<0.0001). The scaler tips showed a fall in displacement amplitude with a reduction in tip length. However, all scaler tips showed variability in the amount oscillation that occurred. This was most pronounced with FSI-SLI-10S.

CONCLUSIONS

This investigation demonstrated that tip wear could affect the performance of dental ultrasonic scaler inserts by reducing their vibration displacement amplitude. Clinicians should be aware of this variability, which may be significant enough to affect clinical procedures.

Cutting on triangle mesh: local model-based haptic display for dental preparation surgery simulation

A new method to realize stable and realistic cutting simulation using an impedance display haptic device and microcomputer is presented in this paper. Material removal or cutting simulation is a critical task in dental preparation surgery simulation. In this paper, a piecewise contact force model is proposed to approximately describe the cutting process. Challenging issues of minimizing the difference between the cutting simulation and haptic contact simulation are analyzed. The proposed contact-based simulation method is developed for a one-dimensional cutting task and can be expanded to three-dimensional cases. Local model-based multirate simulation cutting architecture is proposed and force control of the haptic device is decoupled from the cutting simulation loop, which can both ensure high fidelity of dynamical simulation as well as maintain stability of the haptic device. The cutting operation is realized using spherical and cylindrical shaped tools. An experiment based on the Phantom desktop proves that fidelity in one-dimensional cutting can be realized and stability in three-dimensional cutting can be ensured using the force-filtering method.

An evaluation of the effects of handpiece speed, abrasive characteristics, and polishing load on the flexural strength of polished ceramics

STATEMENT OF PROBLEM

Many studies on the strengthening effects of grinding and polishing, as well as heat treatment on ceramics, are not well standardized or use commercially available industrial polishing systems. The reported effectiveness of these strengthening mechanisms on ceramics may not be applicable to clinical dentistry.

PURPOSE

The purpose of this study was to evaluate the effects of controlled polishing on the flexural strength of dental ceramics by using a custom-made machine that applied standardized loads and speeds that coincided with the mean loads and speeds used by experienced prosthodontists.

MATERIAL AND METHODS

A total of 140 aluminous dental ceramic bar-shaped specimens (Vitadur Alpha Enamel) measuring 1.5 x 2.0 x 25 mm were fabricated and divided into 12 groups (for most groups, n=10). Specimens were untreated, polished with different polishing systems, polished at different speeds, ground and autoglazed, polished and autoglazed, autoglazed and polished, polished with loose (paste) and bonded abrasives, or overglazed. Simulated clinical polishing was performed on the ceramic specimens by using a customized polishing apparatus that allowed independent control over the relevant polishing parameters (abrasive hardness, applied load, linear speed, rotational velocity, and wheel stiffness). Flexural strength (MPa) was measured with a 4-point bending test, and subjective surface roughness was assessed with scanning electron microscopy. Autoglazing was performed at various stages of the polishing sequence to determine the effects of polishing on surface stresses. Mean values, standard deviations, independent-sample t tests, 1-way and 2-way analyses of variance, Dunnett t tests and Kruskal-Wallis tests were applied to the data (alpha=.05).

RESULTS

Under a clinical load of 0.6 N for a coarse polishing wheel, 1.0 N for a medium polishing wheel, and 1.3 N for a fine polishing wheel, a linear speed of 499 mm/min, and a rotational velocity of 10,000 rpm, the use of clinical polishing instruments did not affect the flexural strength of the aluminous ceramics studied (P=.274). At higher rotational velocity (20,000 rpm), specimens polished with the diamond polishing system produced statistically weaker specimens compared with those that had been polished at 10,000 rpm (P=.019). Autoglazing treatment of the diamond-polished specimens did not reverse the strength degradation (P=.125). Conversely, diamond polishing of the autoglazed specimens resulted in significant flexural strength reduction (P=.029). Fine-diamond-bonded abrasive significantly reduced flexural strength (P=.025).

CONCLUSIONS

Simulated clinical polishing at 10,000 rpm did not appear to substantially strengthen or weaken the ceramic specimens. Polishing at 20,000 rpm reduced flexural strength of the ceramic bars.

Oral surgical handpiece use time parameters

PURPOSE

To evaluate the clinical usage time parameters of handpieces used in oral surgical procedures.

METHOD AND MATERIALS

One hundred randomly selected clinical oral surgery exodontia procedures were timed to record lengths of continuous segments of both handpiece use and non-usage. Providers with experience ranging from general dentists to board certified oral surgeons were timed during surgical exodontia treatment involving 1 to 4 teeth of various complexities. Usage times were compared with manufacturers' recommendations that on times should not exceed 20 seconds in any 50-second interval (20/50 rule).

RESULTS

Handpiece run time increased with the number of teeth and surgical case complexity (both P < .001) but was unrelated to operator experience (P = .763), in a 3-predictor model (R2 = 0.20; P < .001). Ninety-four of the 100 cases experienced at least 1 second in violation of the 20/50 rule and 42% of all run seconds were in violation.

CONCLUSION

Clinicians should be aware of recommended handpiece duty use cycles. Manufacturers' recommendations about handpiece use time cycles do not reflect actual clinical usage. Under the conditions of this study, actual surgical handpiece use time was not correlated with user experience. Less experienced providers did require longer to complete treatment, but increased treatment times were due to time spent that did not require surgical handpiece use.

[In vitro comparison of root canal preparation with step-back technique and GT rotary file--a nickel-titanium engine driven rotary instrument system]

The aim of the authors' study was to compare the remaining root canal wall thickness and the preparation time of root canals, prepared either with step-back technique, or with GT Rotary File, an engine driven nickel-titanium rotary instrument system. Twenty extracted molars were decoronated. Teeth were divided in two groups. In Group 1 root canals were prepared with step-back technique. In Group 2 GT Rotary File System was utilized. Preoperative vestibulo-oral X-ray pictures were taken from all teeth with radiovisiograph (RVG). The final preparations at the mesiobuccal canals (MB) were performed with size #30 and palatinal/distal canals with size #40 instruments. Postoperative RVG pictures were taken ensuring the preoperative positioning. The working time was measured in seconds during each preparation. The authors also assessed the remaining root canal wall thickness at 3, 6 and 9 mm from the radiological apex, comparing the width of the canal walls of the vestibulo-oral projections on pre- and postoperative RVG pictures both mesially and buccally. The ratios of the residual and preoperative root canal wall thickness were calculated and compared. The largest difference was found at the MB canals of the coronal and middle third level of the root, measured on the distal canal wall. The ratio of the remaining dentin wall thickness at the coronal and the middle level in the case of step-back preparation was 0.605 and 0.754, and 0.824 and 0.895 in the cases of GT files respectively. The preparation time needed for GT Rotary File System was altogether 68.7% (MB) and 52.5% (D/P canals) of corresponding step-back preparation times. The use of GT Rotary File with comparison of standard step-back method resulted in a shortened preparation time and excessive damage of the coronal part of the root canal could be avoided.

[Cavity micro-morphology following caries removal]

The objective of this research was to observe the effect of different caries removal techniques on human dentin topography. Thirty-six dentin samples of bisected carious human molars were treated with six different caries removal techniques, replicated and then examined by using a scanning electron microscope. The surfaces were observed before and after the smear layer removal at a magnification of 200- and 1000-fold. At a magnification of 200 the sono-abraded samples showed a significantly more undulated dentin topography than samples treated with other techniques. Using Carisolv hand instruments for caries removal resulted both at a magnification of 200 and 1000 in a significantly rougher, flakier and more fissured dentin surface texture compared to other techniques. Microcracks were observed in samples from all excavation methods but most frequently when treated with Carisolv hand instruments. The excavation process results in a dentin topography marked by smooth, flaky and fissured surface textures as well as by microcracks. The relative incidence in which these textures occur may indicate whether the removed dentin was rather cut or fractured.

Chemical analysis and surface morphology of enamel and dentin following 9.6mu CO2 laser irradiation versus high speed drilling

OBJECTIVES

The purpose of the present in vitro study was to determine whether there is a change in the chemical composition and surface morphology of enamel and dentin following 9.6mu CO2 laser irradiation and high-speed drilling.

MATERIALS AND METHODS

Ten permanent, non-carious, young premolars, extracted for orthodontic reasons, were selected. The crowns were separated longitudinally into two equal parts at their mesiodistal axis. Two areas on the inner enamel surface of each specimen and two on the dentinal surface were selected. A high-speed drill and 9.6mu CO2 laser irradiation were applied to the selected enamel and dentinal areas. A random area on the unlased enamel and on the unlased dentin of each specimen served as controls. The morphology of the specimens was evaluated using scanning electron microscopy. Calcium, phosphorus and oxygen levels were measured using an energy dispersive spectrometer.

RESULTS

Mineral analysis revealed no significant difference in the mineral content of the enamel and dentin after laser irradiation or high speed drilling versus the control. Use of the high-speed drill on enamel and dentin resulted in very clear cavity margins, with characteristic grooves, whereas laser irradiation of enamel and dentin did not produce clear margins and the floor of the cavity displayed an irregular surface.

CONCLUSIONS

The 9.6mu CO2 laser appears to be a promising tool in the clinical setting. However, further investigation is indicated to ensure maximum effectiveness.