Leydig cell tumor--comparison of results of radical and testis-sparing surgery in a single center

Twenty-two mesial roots of extracted human mandibular molars were divided into two groups based on root curvature and length. The mesiolingual canals were instrumented using either Flexofiles in a step-back anticurvature filing method, or they were instrumented with engine-driven 0.02 taper nickel-titanium files. Ground sections were prepared at 1-, 2.5-, and 5-mm levels from the working length. The mesiobuccal canal was used as an uninstrumented control for predentin character. Digitizing software was used to calculate the instrumented portion as a percentage of the total canal perimeter. The results indicated no significant difference in overall canal wall planning between the two groups and no significant difference at each of the three levels.     

A comparative study on the effect of three methods of instrumentation on the shape of root canal (an in-vitro study)

This study compared the ability of three types of engine driven instrumentation techniques to negotiate and prepare small, slightly curved root canals. Forty five mesial roots of extracted maxillary and mandibular first permanent molars were classified into three groups. Group (I) was prepared by Canal Leader system, group (II) was prepared by Nickel Titanium files and group (III) was prepared by Canal Master technique. Radiographs of the root canal space before and after preparation was carried out by the aid of an experimental model. Enlarged photographic prints obtained from radiographs were scored for shaping effectiveness of the three techniques in respect to canal course, position & width of apical constriction and lack of ledge formation. The results indicated that the Canal Leader system was an efficient technique in maintaining canal curvature, absence of zipping, transportation or ledge formation in almost all of the specimen tested, followed by the Nickel Titanium files and then the Canal Master technique which produced more straightening and destruction of apical constriction.     

Lichen myxoedematosus associated with human immunodeficiency virus infection--report of two cases and review of the literature

The transportation produced in the apical and middle areas of 30 mesiobuccal root canals of human mandibular molars was evaluated after circumferential instrumentation using stainless steel K-files (group A), nickel-titanium K-files (group B), and clockwise/counterclockwise file rotation using Flexogates (group C). The canals were instrumented with files #15 to #35 in size. Apical transportation was assessed radiographically while that occurring in the middle area was studied microscopically in cross-sections. Although apical transportation was greatest in the canals of group A, this difference was not statistically significant (P > 0.05). With respect to the middle area of the root canal, considerable transportation was observed in 7 of the 30 instrumented roots. Of these, five belonged to group A and two to group B, a difference which was not statistically significant (P > 0.05). The best results for transportation in the middle area of the canal were obtained in group C, in which no transportation occurred. This difference was significant when compared with the transportation observed in group A (P = 0.02) but not with that in group B (P > 0.05).     

Impact of abomasal nematodes on roe deer and chamois body condition in an alpine environment

Endodontically, the maxillary first molar is one of the most misunderstood teeth and presents a variety of considerations for the treating practitioner. Clinically, the mesiobuccal root contains a second root canal system that can be identified and treated more than 75 percent of the time. The thorough clinician must assume all maxillary first molars have four canals until proven otherwise.     

In vivo fluoride profiles at different sites of buccal and lingual enamel surfaces obtained by enamel biopsy of human maxillary first permanent molars in young adults

Twenty male volunteers, average age 24 years, participated in this study. Specimens were obtained by enamel biopsy using 5 microliters of 0.5 M HClO4 for 30 s. Using a regression curve, comparisons of fluoride concentrations were made at different depths. The fluoride concentrations (mean +/- SE) at a depth of 5 microns were highest in the distobuccal (1698 +/- 136), high in the mesiobuccal (1343 +/- 122), low in the distolingual (1119 +/- 107), and lowest in the mesiolingual sites (819 +/- 78). Of the interior enamels (> or = 10 microns in depth), the distobuccal site (1330 +/- 88 parts/10(6) F at 10 microns) had a higher-concentration than all other sites. The fluoride profiles were steepest to shallowest in the order: distobuccal, mesiobuccal, distolingual and mesiolingual. There were no correlations between the enamel fluoride concentrations and the fluoride concentration in parotid saliva. It was concluded that in vivo fluoride profiles of maxillary first molars reflect the wear of the tooth surface with age and the condition of dental plaque deposition, and, to some extent, the site-specific distribution of saliva between buccal and lingual surfaces.     

Novel LQT-3 mutation affects Na+ channel activity through interactions between alpha- and beta1-subunits

This study describes mesial and distal enamel thickness of the permanent posterior mandibular dentition. The sample comprised 98 Caucasian adults (59 males, 39 females) 20 to 35 years old. Bitewing radiographs of the right permanent mandibular premolars and first and second molars were illuminated and transferred to a computer at a fixed magnification via a video camera. Enamel and dentin thicknesses were identified and digitized on the plane representing the maximum mesiodistal diameter of each tooth. The results showed that there were no significant sex differences in either mesial or distal enamel thickness. Enamel on the second molars was significantly thicker (0.3 to 0.4 mm) than enamel on the premolars. Distal enamel was significantly thicker than mesial enamel. There was approximately 10 mm of total enamel on the four teeth combined. Assuming 50% enamel reduction, the premolars and molars should provide 9.8 mm of additional space for realignment of mandibular teeth.     

Incidence of Lightspeed separation and the potential for bypassing

It is important for endodontic instruments to have a low fracture rate. If a fracture does occur, it would be desirable to have the ability to bypass the broken segment and complete the root canal treatment. One hundred sixty-two root canals in 52 maxillary and mandibular first molars were cleaned and shaped with Lightspeed instruments by three endodontists in their private practices. The canals were instrumented using the technique recommended by the manufacturer. All canals were instrumented to at least a size 45 at the working length. Six instruments separated during treatment. All six had been used more times than recommended by the manufacturer. Five of the six were easily bypassed and treatment completed.     

An economic analysis of the investment in nurse anesthesia education

The purpose of this research was to study the prevalence of ectopic eruption of the first permanent molars and possible etiologic factors. A group of 4,232 Thai students, from 6 to 9 years old, was examined. The prevalence of ectopic eruption of the first permanent molars in the subjects was 0.75%. Both the severity of the ectopic eruption and the amount of root resorption on the second primary molars were more pronounced in the maxilla than in the mandible. The important etiologic factors were the eruption path of the first permanent molars relative to reference lines and the size of the mandibular second primary molars. The amount of proximal caries did not seem to affect the prevalence of ectopic eruption.     

Comparative in vitro effectiveness of closed root debridement with fine instruments on specific areas of mandibular first molar furcations. I. Root trunk and furcation entrance

The purpose of this study was to compare curets with a small blade to slim ultrasonic inserts on their efficacy in removing artificial deposits from the root trunk and furcation entrance areas of mandibular molars using an in vitro model simulating a clinically closed root debridement approach. The study was conducted on 100 artificial mandibular first molars (50 right side and 50 left side) with anatomical roots. Root trunks, furcation entrances, and furcation areas of each molar were colored by a coat of black model paint. The teeth were fixed in a custom acrylic model and maintained in a firm position by modified acrylic occlusal splints. The root areas were covered with a heavy rubber dam imitating gingival tissue. The model was attached to a mannequin and mounted on a dental chair. Fifty molars (25 right, 25 left) were instrumented with the experimental curets and an equivalent number of molars with the ultrasonic inserts. The instrumentation was carried out by one experienced operator, spending 4 minutes on each molar. The instrumented areas were individually analyzed to determine the percentage of deposits remaining, using a computerized imaging routine system. One-way analysis of variance was conducted to test for differences between both types of instruments. Results revealed that the curets were significantly more efficient (P < 0.01) than the ultrasonic inserts in removing paint from both root trunks and furcation entrances. These findings should be corroborated in a clinical study to determine the potential value of the instruments tested during initial therapy or supportive care of involved mandibular furcations.     

Effect of non-erupted third molars on roots of approximal teeth. A radiographic, clinical and histologic study

This study was undertaken to evaluate clinically and histologically root resorption in extracted human second molars in close proximity to non-erupted third molars. The control group consisted of extracted second molars that were proximal to fully erupted third molars. Eight out of the 11 teeth in the study group presented different degrees of radiographic root resorption, nine presented clinical resorption, and all 11 had histologic evidence of root resorption. In the control group, no signs of root resorption were seen radiographically or clinically. Histologically, limited sites of resorption were identified in all teeth, which were partially repaired by cellular cementum. Histologic observation of study specimens revealed root surface resorption in 10 out of the 11 teeth, one showing replacement resorption as well. Inflammatory resorption was observed in the three most advanced cases in the study group. Reparative cementum partially lining resorbed areas was evident in all teeth with surface resorption. Within the limits of this study, radiographic identification of distal root resorption of second molars in close proximity to non-erupted third molars appears reliable. The findings may support the hypothesis that the presence of a non-erupted third molar in close proximity to the distal root of the second results in root resorption.     

A clinical and radiographic study of 25 autotransplanted third molars

This paper is a report on 25 autotransplantations of third molars with complete root formations. The study consists of 23 patients in whom 25 third molars were transplanted. The mean age was 29.6 years (range 20-54). In nine cases third molars were directly transplanted into the new socket. In 11 cases the sockets were widened and made deeper with a bur. In five cases the recipient beds were made by splitting osteotomy of the alveolar region. The transplanted third molars were stabilized with silk sutures, resin, wire splint or circumferential wiring for 1-6 weeks. Two-three weeks after transplantation, the root canals were treated and filled. After operation, the marginal and the periapical conditions were examined clinically and radiographically. The transplanted teeth clinically appeared to become firmer with the passage of time. Progressive root resorption was not found and good results were obtained. This study shows that autotransplantation of third molars with complete root formation produces an acceptable result using the procedures outlined.     

The effect of ultrasonics on sealer distribution and sealing of root canals

The purpose of this study was to compare the ultrasonic and hand methods of sealer placement using three types of sealers: Sultan "Grossman's formula," AH-26, and CRCS. The effect of these methods on radiographic density, sealer distribution, and on the apical seal of the different sealers was evaluated. The in vitro experiment was carried out using human extracted mandibular incisors and mesio-buccal roots of maxillary first and second molars. Following standardized canal instrumentation, 120 single canal mandibular incisors were randomly assigned to six groups, depending on the type of sealer and method of sealer placement (hand versus ultrasonic). An additional ten teeth were used as controls. In the molar groups 40 canals were randomly assigned to two groups, with the method of sealer placement as the variable. Eight canals were used as controls. Postsealer analyses using radiographic density scores transformed to mm of sealer indicated that ultrasonics was superior to manual placement only for CRCS. Taken together, our investigation suggests that ultrasonics may enhance the placement of some sealers (i.e. CRCS) but not of others (i.e. AH-26 or Sultan). Method of sealer placement had no effect on apical leakage and therefore apparently on apical seal.     

Treatment response to maxillary expansion and protraction

A prospective clinical trial was conducted to determine the skeletal and dental contributions to the correction of overjet and overbite in Class III patients. Thirty patients (12 males and 18 females with a mean age of 8.4 +/- 1.7 years) were treated consecutively with protraction headgear and fixed maxillary expansion appliances. For each patient, a lateral cephalogram was taken 6 months before treatment (T0); immediately before treatment (T1); and 6 months after treatment (T2). The time period (T1-T0) represented changes due to 6 months of growth without treatment; (T2-T1) represented 6 months of growth and treatment. Each patient served as his/her own control. Cephalometric analysis described by Bj?rk (1947) and Pancherz (1982a,b) was used. Sagittal and vertical measurements were made along the occlusal plane (OLs) and the occlusal plane perpendicular (OLp), and superimposed on the mid-sagittal cranial structure. The results revealed the following: with 6 months of treatment, all subjects were treated to Class I or overcorrected to Class I or Class II dental arch relationships. Overjet and sagittal molar relationships improved by an average of 6.2 and 4.5 mm, respectively. This was a result of 1.8 mm of forward maxillary growth, a 2.5-mm of backward movement of the mandible, a 1.7-mm of labial movement of maxillary incisors, a 0.2-mm of lingual movement of mandibular incisors, and a 0.2-mm of greater mesial movement of maxillary than mandibular molars. The mean overbite reduction was 2.6 mm. Maxillary and mandibular molars were erupted occlusally by 0.9 and 1.4 mm, respectively. The mandibular plane angle was increased by 1.5 degrees and the lower facial height by 2.9 mm. Individual variations in response to maxillary protraction was large for most of the parameters tested. Significant differences in treatment changes between male and female subjects were found only in the vertical eruption of mandibular incisors and maxillary and mandibular molars. These results demonstrate that significant overjet and overbite corrections can be obtained with 6 months of maxillary protraction in combination with a fixed expansion appliance.     

Frequency of endodontic treatment in Kuwait: radiographic evaluation of 846 endodontically treated teeth

A retrospective study was conducted to evaluate the radiographic films of 846 endodontically treated teeth at Benied Al Ghar Dental Center in Kuwait. The most frequently treated tooth was the mandibular first molar (17.4%). The number, percentage, and distribution of the roots, root canals, and apical foramina were reported by individual tooth. The clinical findings were compared to the results of previously related in vitro and in vivo studies.     

Comparison of two endodontic handpieces during the preparation of simulated root canals

The objective of this in vitro study was to compare and assess two endodontic handpieces during the preparation of simulated root canals. One hundred and sixty simulated root canals in clear resin blocks, of two angles and positions of curvature, were prepared using either Shaper files activated by the MM1500 Sonic Air handpiece (Micro-Mega, Besan?on, France) or Excalibur files activated by the W & H Excalibur 969 handpiece (W & H, Bürmoos, Austria). Files of 21-mm or 25-mm length were used. When preparing the canals, the files were used either in line with or perpendicular to the canal curvature. Preparation of the canals was carried out using a technique described in the manufacturers' literature. A variety of parameters were used to compare the handpieces, including an assessment of the canal preparation time, the deformation or fracture of instruments, loss of canal length, weight loss from the resin blocks and the overall postpreparation canal shape. Both handpieces provided an efficient and easy method of preparing and shaping the root canal with little operator fatigue. The MM1500 Sonic Air handpiece took significantly more time (P < 0.001) to prepare the canals and was associated with both more loss of working length (P < 0.05) and more loss of weight (P < 0.001). Both handpieces created a high percentage of aberrations in the shapes of prepared canals. The MM1500 Sonic Air handpiece created significantly more aberrations than the Excalibur handpiece (P < 0.05 for zip and elbow, P < 0.05 for danger zone and coronal narrow). The effects of the variables, canal curvature, file length and the plane of use of the file, on the performance of the handpieces, were also assessed.     

Infertile women with and without endometriosis: a case control study of luteal phase and other infertility conditions

The furcation involvement of 100 molars in 25 patients suffering from moderate to advanced periodontitis was investigated. The horizontal probing attachment level (PAL-H) within the furcations was assessed 2x within 2 weeks using the pressure-calibrated (0.25 N) flexible plastic universal explorer version of the TPS probe (TPS). To determine the measurement error of PAL-H assessments, the standard deviation of single measurements was calculated. The measurements were repeated using a colour-coded Nabers probe and compared to the TPS assessments. 253 furcations were evaluated (100 buccal, 47 lingual, 53 mesiolingual and 53 distolingual, respectively). For buccal, lingual, mesiolingual and distolingual furcations, the standard deviations were 0.486 mm, 0.598 mm, 0.846 mm, 1.039 mm, respectively. Measurement error was less in buccal and lingual furcations than in mesiolingual and distolingual sites (p < 0.005). The agreement of replicate measurements of furcation degrees was excellent for buccal and lingual furcations (weighted kappa [standard error] 0.824 [0.076] and 0.779 [0.107], respectively), but only moderate for mesiolingual and distolingual furcations (weighted kappa 0.688 [0.096] and 0.544 [0.101], respectively). Only in distolingual sites there was a significant (p < 0.025; paired t-test) underestimation of PAL-H by the TPS as compared to the Nabers probe. At all locations the TPS underestimated furcation degrees significantly (p < 0.1; Stuart-Maxwell's chi 2) as compared to Nabers probe. Measurement error of mesiolingual and distolingual furcations was significantly higher than of buccal or lingual sites. The reproducibility of PAL-H measurements in furcations using TPS is comparable to data published for scorings with colour-coded Nabers probes. Through and through furcations are likely to be underestimated by using the flexible plastic version of the TPS probe. Hence, it seems to be unsuitable for a proper assessment of the degree of furcation involvement.     

Strength of core build-up materials in endodontically treated teeth

PURPOSE: To compare the in vitro strength of a reinforced glass ionomer and a light-cured glass ionomer used as an alternative to amalgam in core construction to restore endodontically treated mandibular molar teeth. MATERIALS AND METHODS: The root canals of 120 extracted human mandibular molar teeth were prepared chemomechanically and obturated with laterally condensed cold gutta-percha. The crown of each tooth was sectioned leaving only one cusp standing. Gutta-percha was removed from the pulp chamber in all teeth. The volume of the pulp chamber was measured and the teeth ranked in ascending order of chamber volume. The specimens were divided into six groups of 20, allocating teeth with similar chamber volumes into each group. In three of the groups, gutta-percha was removed from the coronal 3-4 mm of each root canal. The teeth were restored with one of three materials, a cermet cement (Ketac-Silver), a resin-reinforced glass ionomer (Vitremer), or amalgam (Contour). Core preparation was carried out after 48 hours, reducing each core height to 6 mm. The specimens were thermocycled for 24 hours and then mounted in dental stone. A control group of 20 unrestored human mandibular molars was mounted in cold cure acrylic. Each tooth was tested in a Nene machine with a compressive load applied at 90 degrees to the occlusal surface at a crosshead speed of 5 mm/minute. RESULTS: There was no statistically significant difference between the experimental groups (P > 0.05), but the control group was significantly stronger (P < 0.001). Extension of core material into the coronal root canal system did not increase the fracture resistance of any of the experimental materials. Regression analysis of the results revealed no correlation between the volume of the pulp chamber and the load to fracture.     

Root canals in two-rooted maxillary second molars

The aim of this study was to register the root canal number, root canal position, and root canal cross-section in human two-rooted, permanent maxillary second molars. One hundred and fifty-nine such teeth extracted in Denmark were cross-sectioned at the mid-root level and apically in accordance with precise guidelines. The observations were made in a stereomicroscope, corresponding to the above-mentioned section levels. At mid-root there were two canals present in 11% of the teeth examined; the canals were located mesially and distofacially, mesiofacially and distally, or facially and lingually. Three canals positioned mesiofacially, distofacially, and lingually were observed in 89% of the teeth. At the same level 62% of the canal cross-sections were noncircular, some being, for instance, C-shaped, whereas 38% of the cross-sections were circular. Apically, two canals were found, representing 19% of the teeth, with the canal position as at mid-root; 81% of the teeth were three-canaled with the same canal position as at mid-root. At the apical level 60% of the canal cross-sections were noncircular, whereas 40% of the cross-sections were circular.     

An in vitro comparison of thermoplasticised gutta-percha obturation techniques with cold lateral condensation

This study compared the apical sealing ability, obturation time and extrusion of gutta-percha and sealer when root canals were obturated using either cold lateral condensation or one of the three methods using thermoplasticised gutta-percha (Alpha Seal, Thermafil or JS Quick Fill) in vitro. One hundred and thirty-one root canals from 78 extracted human teeth were used; 116 canals were divided into five groups so that they were balanced with respect to prepared canal anatomy, and the remaining 15 canals were used as positive and negative controls. The canals in the first four groups were prepared with hand files using the step-down technique to a standard apical size and flare. The last group was prepared using engine-driven rotary nickel-titanium files (McSpadden) to a similar apical size and flare. One of the four obturating techniques was used to fill the canals in each of the first four groups. The fifth group was obturated using the Alpha Seal technique. The roots were immersed in india ink, demineralised and rendered transparent to assess the extent of maximum lincar dye penetration. The Alpha Seal groups had the highest number of specimens without any leakage. There was a significant difference in the proportions of specimens that did not leak when the Alpha Seal (P < 0.01) and cold lateral condensation groups (P < 0.05) were compared with JS Quick Fill. Cold lateral condensation had a higher proportion of specimens with leakage in canals with curvature greater than 20 degrees than in canals with curvatures less than 20 degrees (P < 0.05). The curvature of canals had no effect on the sealing ability of the other techniques. The method of canal preparation had no effect on the sealing ability of Alpha Seal. Alpha Seal, Thermafil and JS Quick Fill were significantly quicker to perform than cold lateral condensation.     

In vitro permeability of furcation dentin in permanent teeth

Extracted unerupted permanent third molars with the occlusal half of the crown and apical half of the roots removed were cemented to Plexiglas blocks. Using a positive pressure system in which the movement of fluid across the dental tubules could be measured, the permeability of furcation dentin was measured before and after alteration of the furcation thickness. Subsequently, measurements of reduction in thickness of cementum and dentin were performed. Furcation dentin permeability was found to increase as the cementum and dentin thickness was reduced and the smear layer removed. The permeability values obtained for the furcation dentin were similar to those found in radicular dentin in general, indicating that root dentin has a low permeability and that it has good barrier properties. The data would suggest that any bone resorption seen under the furcation region of permanent molars is more likely to be due to the presence of accessory canals than due to permeation directly through furcation hard tissues.