Dentin removal efficiency of six endodontic systems: a quantitative comparison.

The dentin removal efficiency of current endodontic systems, based on the amount of dentin removed in 1 mm of canal axial length, was determined for working times of 1 and 2 min. Six endodontic systems were compared: The Giromatic with Heli-Giro files, the Sonic-Air with Shapers, the Mecasonic with Shapers, the Cavi-Med with K files, the Cavi-Med with Shapers, the Excalibur with its own K files. Generally speaking, the efficiency of each device depends on the duration of instrumentation, on the type of file used, and on its mode of activation. For 1 min of instrumentation, the Mecasonic+Shaper was the most efficient system. For 2 min of instrumentation, the original adaptation of the Shaper on the Cavi-Med gave the highest activity. Concerning the files used in ultrasonics, the Shaper seems to be more efficient than the K file. As for the sonics, the Excalibur+file system gave results comparable to those of the Mecasonic+Shaper; both of these devices were twice as efficient as the Sonic-Air+Shaper.     

Canal-centering ability of two rotary file systems

The ability of two nickel-titanium rotary file systems to maintain the original path of the canal were compared by using a new split-mold design (the Endodontic Cube). The mesial roots of 10 mandibular first- and second-molar teeth with separate canals from orifice to foramen were divided into two groups based on canal curvature and morphology. Working lengths for each canal were determined 1.0 mm short of where the file tip was visible on the external surface of the root. The teeth were embedded in composite resin by using the Endodontic Cube as a mold and sectioned into five pieces. ProFile Ni-Ti.06 taper Series 29 and ProFile GT rotary instrumentation techniques were randomly assigned to one of the canals and used in a crown-down fashion to a 0.217 ProFile and a 0.06 GT master apical file, respectively. Digital photographs were made of the middle three sections and software features of Adobe Photoshop were used to measure the movement of the canal centers by superimposing the images of the instrumented and uninstrumented canals. Data were analyzed using ANOVA. Both systems remained centered within the canal with minimal deviation from the original canal path. The largest mean movement was less than 0.15 mm. The Endodontic Cube was an effective tool for studying and comparing instrumentation techniques.     

Mechanical aspects of a multidirectional, angular stable osteosynthesis system and comparison with four conventional systems.

BACKGROUND: Following open reduction, internal fixation of fractures of the mandible is predominantly achieved using plates and screws. Today, a multitude of osteosynthesis systems are available on the market. One therapy modality, primarily developed for orthopaedic surgery, is using angular stable osteosynthesis plate systems. The dominating principle of these is the bond between screw and plate following insertion. This principle of an "internal fixateur" results in a more stable fixation of the fragments associated with less compression of the bone surfaces. MATERIAL: A new multidirectional osteosynthesis system (TiFix=Smartlock, Hamburg - Germany) was modified to fit the maxillofacial region and compared with four other well established osteosynthesis systems developed by Mondial, Medicon, Synthes, Leibinger-Stryker, one of these (Unilock by Synthes) being also angular stable. The resistance to deformation in varying directions was investigated following fixation in four different materials. RESULTS: The TiFix system proved more resistant to deformation even when mounted with fewer screws than the non-angular stable systems. CONCLUSION: This system results in greater stability even when fewer screws are used. For the clinician this means smaller access incisions, less soft tissue trauma, better aesthetic results, decreased duration of operation and a reduction of costs.     

Subjective image quality comparison between two digital dental radiographic systems and conventional dental film

ObjectivesDigital radiography has become an integral part of dentistry. Digital radiography does not require film or dark rooms, reduces X-ray doses, and instantly generates images. The aim of our study was to compare the subjective image quality of two digital dental radiographic systems with conventional dental film.Materials & methodsA direct digital (DD) ‘Digital’ system by Sirona, a semi-direct (SD) digital system by Vista-scan, and Kodak ‘E’ speed dental X-ray films were selected for the study. Endodontically-treated extracted teeth (n = 25) were used in the study. Details of enamel, dentin, dentino-enamel junction, root canal filling (gutta percha), and simulated apical pathology were investigated with the three radiographic systems. The data were subjected to statistical analyzes to reveal differences in subjective image quality.ResultsConventional dental X-ray film was superior to the digital systems. For digital systems, DD imaging was superior to SD imaging.ConclusionConventional film yielded superior image quality that was statistically significant in almost all aspects of comparison. Conventional film was followed in image quality by DD, and SD provided the lowest quality images. Conventional film is still considered the gold standard to diagnose diseases affecting the jawbone.RecommendationsImproved software and hardware for digital imaging systems are now available and these improvements may now yield images that are comparable in quality to conventional film. However, we recommend that studies still use more observers and other statistical methods to produce ideal results.     

Retention of two fluoride pit-and-fissure sealants in comparison to a conventional sealant

AIM: The aim of this investigation was to study the retention rates in children of two fluoride fissure sealants, an experimental fluoride-glass formulation and a commercial one, in comparison to a conventional sealant, at 3, 6 and 12 months. DESIGN: The study was performed in a randomized double-blind fashion. SETTING: The investigation was carried out in the Children's Clinic at Leeds Dental Institute. METHODS: A total of 74 first and 29 second permanent molars in 25 children aged 6-16 were assigned randomly to one of the three sealant-groups using a table of random numbers. During sealant application occlusal pits and fissures were cleaned with a three-in-one syringe and a blunt probe, etched for 20 seconds, washed, dried and light-cured for 30 seconds. Retention of the sealants was assessed as either completely retained, partially retained or missing at 3, 6 and 12 months. RESULTS: The results showed that complete retention for fluoride-glass sealant, Delton Plus and Delton was: at 3 months 69.69%, 81.25% and 80.64% respectively, at 6 months 64.51%, 74.19% and 76.66% respectively, and at 12 months 61.29%, 67.74% and 70% respectively. CONCLUSIONS: No significant difference (P > 0.05) was found among the three materials in retention rates at each follow-up period.     

Dose reduction of two digital sensor systems measuring file lengths

ObjectivesThe aim of this study was to determine the effect of dose reduction on the image quality of two sensor systems with automatic greyscale adjustment.Study designsTwo digital sensor systems, Sidexis (Siemens, Bensheim, Germany) and Digora (Soredex, Helsinki, Finland), were tested. The image quality of the systems was determined by comparing lengths of endodontic files (025, 020, 015, and 010 files) and a premolar root in the digital images with lengths on conventional radiographic films. For the experiments the exposure was changed to 100%, 50%, 25%, 12.5%, 6.25%, and 3.125% of that for Ektaspeed films.ResultsThe lengths of 025 and 020 files and the premolar root in the digital images were comparable with the lengths on films even if the exposure was reduced to 6% of that used for Ektaspeed films. The lengths of 015 files reduced as the exposure was reduced. The lengths of 010 files were significantly shorter than the lengths on films.ConclusionsWith the systems tested, a dose reduction of approximately 95% compared with Ektaspeed films is possible to determine the lengths of a premolar root and 025 and 020 files. For thinner objects a dose reduction is questionable.     

Irritation fibroma removal: a comparison of two laser wavelengths

Laser wavelengths are available that offer dentists treatment options for both hard and soft oral tissues. This article discusses the benefits of removing hypertrophic soft tissue by using an all-tissue laser. A clinical case is presented involving the use of both an 810 nm diode laser and a 2,780 nm Er,Cr:YSGG laser to remove two irritation fibromas, both located on the left cheek of the same patient. This unique perspective was ideal for comparing the healing of each wound. The Er,Cr:YSGG appeared to have a less traumatic effect on target tissue and offered improved postoperative healing, faster recovery time, and less trauma than traditional surgical modalities.     

Evaluation of the effects of the hybrid Pendulum in comparison with the conventional Pendulum appliance

Objective:To evaluate the anchorage control and distalization of maxillary molars with the hybrid Pendulum appliance and to compare the results with a conventional Pendulum appliance.Materials and Methods:This study was carried out on the pre-(T0) and post-(T1) treatment lateral cephalograms and dental casts of 43 patients with Angle Class II molar relationships who were treated with conventional or hybrid Pendulum appliances. The hybrid Pendulum (HP) group consisted of 22 patients (14 females; eight males; mean age 14.3 ± 2.43 years) and treatment results were compared with a conventional Pendulum appliance (CP) group, which consisted of 21 patients (15 females; six males; mean age 14.6 ± 3.39 years). Intragroup comparisons were made with Wilcoxon test and intergroup comparisons were made with Mann-Whitney U-test (P < .05).Results:The mean distalization duration was 0.70 ± 0.25 years in the HP group and 0.83 ± 0.4 years in the CP group. Maxillary first molars showed significant distal movement and tipping of 4.25 mm and 9.09° in the HP group, and 3.21 mm and 9.86° in the CP group. Loss of anchorage at the first premolars was significantly smaller in the HP appliance group compared to CP group. The second premolars distalized spontaneously in the HP group while they mesialized significantly in the CP group. Proclination and protrusion of maxillary incisors were greater with the CP appliance compared to the HP appliance.Conclusions:Maxillary molar distalization was achieved with both appliances. Mesialization of the anchorage unit was controlled successfully with the hybrid Pendulum; however, the conventional Pendulum appliance caused anchorage loss.     

The efficiency of a new aspirating system

A new method of aspirating has been introduced to local anaesthetic technique in dentistry. It is convenient and provides a reliable aspirating force, and can be used with 27 or 25 gauge needles.     

Evaluation of a new method for silver point removal

A new device for removing silver points was evaluated. The instrument consists of a trepan bur to expose the end of the silver point and a hollow tube which fits over the exposed tip and is bonded to it with cyanoacrylate adhesive. Twenty groups with 10 extractors and silver points in each group were tested for adhesive strength with respect to overlap between extractor and silver point, snugness of fit, and setting time of the adhesive. The adhesive strengths were evaluated using the Instron Universal Testing Machine. Adhesive strengths of 2 to 5 kg were readily achieved, and such adhesion should be adequate under typical clinical conditions for silver point removal. The amount of overlap (in the range of 1 to 3 mm) and snugness of fit were significant in relation to adhesive strengths. A setting time of 5 min was adequate for maximum bonding, except when there was loose fit between the extractor and the silver point. Clinically, the device appears to be an effective method for silver point removal.     

Evaluation of the chemomechanical removal of dentine caries in vivo with a new modified Carisolv gel

Carisolv is a minimally invasive method for softening and removing dentine caries. A new, modified Carisolv gel has been developed in order to optimise the efficiency if its chemical caries dissolution. The aim of the present study was to compare the caries removal efficiency of the original gel with that of the new gel, which contains almost double the concentration of sodium hypochlorite. Ten dentists treated 202 cavities in 170 patients; 104 cavities were randomised to the new gel and 98 to the original gel. Their mean treatment times for caries removal were 6.7±4.1 min and 7.6±4.2 min, respectively (P>0.05). In close-to-pulp lesions, constituting 32% of the cavities, the mean times for caries removal were 9.0±7.0 min and 11.6±4.4 min for the new and original gels, respectively (P<0.01). Questionnaires revealed that 81% of the patients preferred chemomechanical treatment to drilling. In conclusion, the improved efficiency of the modified Carisolv gel did reduce the time for caries removal in deep lesions. However, it still needs more time than conventional drilling.     

Measurement of stain removal in vitro: a comparison of two instrumental methods

Abstract  Aim: The aim of this study was to compare an established spectrophotometrical approach for the measurement of stain removal in vitro with a new digital image analysis system. Method:  Eighteen acrylic blocks were stained by cycling them through human saliva (2 min), chlorhexidine (2 min) and tea (1 h), rinsed with deionized water and left to air dry. The absorbance of each block was then measured at 395 nm using a single-beam spectrophotometer. The lightness ( L -value) of the stained blocks (after a baseline correction) was measured using digital image analysis. Image acquisition and L -values were obtained using Adobe Photoshop software. The stain removal ability of two whitening toothpastes and deionized water was tested by immersing each stained block in a test slurry (15 g paste/60 ml deionized water) for 1 min, rinsing and finally left to air dry. This cycle was repeated until the blocks had 5 min exposure to the slurry. Absorbance values from spectrophotometry and L -values by image analysis were obtained after each cycle. Results: Fleiss' coefficient of reliability for intra-operator repeatability of the image analysis system and spectrophotometry was 0.999 for both methods which shows excellent reliability. Pearson's correlation coefficients for the two methods (stain build-up) were 0.976. Test products A, B and C gave correlations of 0.962, 0.998 and 0.817 respectively (stain removal), significant at the 0.01 level. Conclusion: The image system is a reliable alternative measurement method validated here against spectrophotometry for stain removal in vitro , and can provide full colour measurement.     

A comparison of dentine removal using safety or conventional Hedstrom files

Abstract Mandibular molars (n=20) were divided and the mesial roots mounted in an acrylic mould which allowed them to be removed, sectioned horizontally and then reassembled. The furcal root canal wall thickness 7 mm from the apex was measured prior to instrumentation. The roots were allocated to two groups (n=10). One group was instrumented using the step back technique with safety Hedstroms in one canal and conventional Hedstrom files in the other canal. The second group was instrumented using a crown down approach (using files and Gates Glidden drills to provide early radicular access). The furcal root canal wall thickness was then remeasured and the amount of dentine removed calculated. The results showed that the safetv Hedstrom file removed less dentine from the furcal region of the canal compared to the conventional Hedstrom file. This however was not statistically significant (Paired t test, n=10, p>0.05). The amount of dentine removed using the crown down technique was significantly greater than that using the step back technique (Two sample t, n = 20, p<0.01). In conclusion, less dentine was removed from the furcal region with safety Hedstrom files compared to conventional Hedstrom files; however, Gates Glidden drills removed more dentine than either type of hand file.     

In vitro comparison of the efficacy of Carisolv and conventional rotary instrument in caries removal

summary The purpose of this in vitro study was to compare the efficacy of a new chemomechanical caries removal agent, Carisolv^TM (MediTeam AB, Sävedalen, Sweden), with conventional slow‐speed rotary instrument (bur). Fourteen extracted human molar teeth with deep dentine caries and no enamel coverage were selected for the study. Their laser fluorescence values were over 30 (DIAGNOdent^®; KaVo, Biberach, Germany). After the teeth were sectioned through the centre of the carious lesion, one half was removed with conventional drilling (bur); the other half was removed with Carisolv gel. Removal of carious dentine was continued until the lesion was deemed caries‐free by visual and tactile criteria. The preparation time for each caries removal technique was also noted. The two halves of each tooth were fixed in 10% buffered‐formaldehyde for 1 week. They were then decalcified, dehydrated and embedded in paraffin blocks for histological studies. After taking serial sections of 5 μm thickness, sections were mounted on glass slides, deparaffinized, dehydrated and stained with toluidine blue for observation under a light microscope. Each section was examined for the presence of bacteria. Complete removal of caries was achieved in 13 (93%) of 14 conventionally prepared teeth, and 5 (36%) of 14 chemomechanically prepared teeth (P < 0·05). Mean (±SD) time for caries removal was 272 s (±53·3) with Carisolv, and 116 s (±49·4) with drilling. The results of this study suggest that conventional rotary instrument (bur) was more effective than Carisolv in removal of carious tissue and also takes shorter time.     

An in vitro comparison of the rake angles between K3 and ProFile endodontic file systems

The purpose of this study was to compare rake angles of the ProFile and K3 file systems. Twenty-five 40/0.06 taper files were obtained for each system. Five files from the same manufacturer were placed perpendicularly into a vial of Epoxicure Resin and left to set for 24 h. The set-ups were removed from the vials and each were sectioned 5 mm from the tip of the files and polished. A photomicrograph was taken of each file with 100x magnification. Five sets of ProFile and five sets of K3 files were processed in this manner. Images were captured digitally, and rake angles of each file were measured. Multivariate ANOVA found a significant difference (p < 0.001) among the three negative rake angles of the ProFile system compared with the K3 system.     

A comparison of self-ligating and conventional orthodontic bracket systems.

Abstract

This ex-vivo study compared the static frictional resistance of three self-ligating brackets with a conventional steel-ligated Ultratrimm bracket. The effects of archwire size (0.020, 0.019 x 0.025 and 0.021 x 0.025-inch), bracket/archwire angulation (0, 5 and 10 degrees) and the presence of unstimulated human saliva were investigated. The study demonstrated that both increases in wire size and bracket/archwire angulation resulted in increased static frictional resistance for all bracket types tested, with the presence of saliva having an inconsistent effect. Mobil-Lock Variable-Slot had the least friction for all wires for 0 degree angulation. However, with the introduction of angulation, the values were comparable to those of the other brackets. Activa brackets had the second lowest frictional resistance, although high values were found with 0.019 x 0.025-inch wires. SPEED brackets demonstrated low forces with round wires, although with rectangular wires or in the presence of angulation, friction was greatly increased. Ultratrimm brackets produced large individual variation, confirming the difficulty in standardizing ligation force, although under certain conditions, significantly larger frictional forces were observed. In conclusion, self-ligating brackets showed reduced frictional resistance in comparison to steel ligated brackets only under certain conditions.