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Biomedical subjects

W G Schindler

Publications and source records attributed to W G Schindler.

At least 19 recordsLinked to original sources
PubMed2001

Effect of ultrasonic vibration and various sealer and cement combinations on titanium post removal.

The purpose of this study was to determine the effect of ultrasonic vibration on the force required to remove prefabricated posts. Ninety-six extracted human canines were divided into eight groups, which were prepared and obturated with gutta-percha and either a eugenol-containing (Roth's 801 Elite) or eugenol-free (AH26) sealer. Titanium #6 Parapost XH posts were cemented with either zinc phosphate or Panavia 21 resin cement. One half of the sample was subjected to ultrasonic vibration for 16 min at the post-dentin interface, whereas the other half received no vibration (controls). Each combination of sealer, cement, and vibration status was subjected to tensile load to failure using an Instron testing machine. Posts cemented in teeth obturated with gutta-percha and AH26 sealer demonstrated significantly greater resistance to dislodgement, compared with teeth obturated with gutta-percha and Roth's 801 Elite sealer. There was no statistical difference in retention of posts cemented with either zinc phosphate or Panavia 21, regardless of the sealer used. Additionally ultrasonic vibration increased post retention for both cements.

Analysis of Variance↗
PubMed2001

An in vitro evaluation of the accuracy of the root ZX in the presence of various irrigants.

The purpose of this study was to evaluate the accuracy of the Root ZX in vitro in the presence of a variety of endodontic irrigants. The in vitro model, described by Donnelly, consisted of refrigerated gelatin made with 0.9% sodium chloride instead of water. The following irrigants were tested: 2% lidocaine with 1:100,000 epinephrine, 5.25% sodium hypochlorite, RC Prep, liquid EDTA, 3% hydrogen peroxide, and Peridex. A total of 30 extracted, single-rooted teeth were used. The experimental measurements in the presence of the various irrigants were compared with the actual canal lengths. The present data indicate that the Root ZX electronic apex locator reliably measured canal lengths to within 0.31 mm and that there was virtually no difference in the length determination as a function of the seven irrigants used. These results strongly support the concept that the Root ZX is a useful, versatile, and accurate device for the determination of canal lengths over a wide range of irrigants commonly used in the practice of endodontics.

Analysis of Variance↗
PubMed2001

Post retention: the effect of sequence of post-space preparation, cementation time, and different sealers.

Many endodontic sealers contain constituents that have been shown to inhibit the polymerization of resin cements. This may be important when prefabricated posts are cemented at the same appointment as root canal obturation. This study evaluated the effects of cementing posts with a resin cement immediately or at a delayed time period after obturation using Roth's 801 Elite Grade or AH26 sealer cements. The contribution of mechanical post-space preparation was also assessed as a critical variable. One hundred twenty extracted canines were randomly divided into eight experimental groups. The variables evaluated were the order of post preparation (either before or after obturation), the type of sealer used, and the time of post cementation. All teeth received a stainless steel #6 Parapost XP cemented with a resin cement, Panavia 21. Each experimental group underwent tensile testing for retention using an Instron universal testing machine. For both sealers posts cemented in teeth in which the canal was obturated before post-space preparation and thus had sealer-contaminated dentin removed by the space preparation procedure had significantly higher retentive values than those obturated after post-space preparation in which contaminated dentin might remain. Sealer used and time of cementation had no specific effect on retention. Achieving a clean, "freshened" dentinal surface during mechanical post-space preparation seems to be a critical variable for post retention when a resin cement is used.

Analysis of Variance↗
PubMed2001

Epidemiological evaluation of the outcomes of nonsurgical root canal treatment in a large cohort of insured dental patients.

Selected outcomes following initial nonsurgical root canal treatment (NSRCT) procedures were retrospectively assessed using an insurance company database of 110,766 nonsurgical root canal procedures that were completed by endodontists and their referring general dentists. A subset of 44,613 cases, with a minimum required follow-up time of 2 yr, showed incidences of extraction, retreatment and periradicular surgery equal to 5.56%, 2.47%, and 1.41%, respectively. The incidence of subsequent extraction increased with patient age. Teeth that were not restored after root canal therapy were significantly more likely to undergo extraction than restored teeth. Although the practice pattern for endodontists consisted of a significantly higher proportion of molars (48% more; p < 0.001) and a smaller proportion of anterior teeth (43% less; p < 0.001) than general dentists, both groups of providers had comparable rates of untoward events. These data strongly support the hypothesis that the specialist practice provides similar rates of clinical success compared with other providers, even when treating significantly more complex NSRCT cases. Overall, 94.44% of nonsurgical root canal treated teeth remained functional over an average follow-up time of 3.5 yr. These results are an important indication of the benefits of endodontic treatment when provided in an integrated health care delivery system of endodontists and their referring general dentists.

Adolescent↗
PubMed1999

Ideal endodontic access in mandibular incisors.

Straight-line access in mandibular incisors facilitates locating and debridement of the canals. The purpose of this study was to plot where ideal access should be located in mandibular incisors to obtain straight-line access to the apical third of the root canal and to determine if a correlation exists between incisal edge wear and position of access opening. Two hundred and seventy-nine mandibular incisors were radiographed in clinical and proximal views. Straight-line access was determined by finding midpoints in the canal at two levels and extending a line connecting the points through the crown. Teeth were graded as to the condition of the incisal edge. Ideal straight-line access was determined to be at the incisal edge in 72.4% of the teeth, whereas in 27.6% of the teeth it was to the facial of the incisal edge. As the wear of the incisal edge increased, the ideal access moved from the facial toward the incisal.

Chi-Square Distribution↗
PubMed1999

Longitudinal microleakage evaluation of Super-EBA as a root-end sealing material.

This study evaluated the sealing ability of fast and regular set Super-EBA with different powder-to-liquid ratios as a root-end filling material. Fifty extracted maxillary central incisors were uniformly cleaned and shaped using a crown-down technique with Gates-Glidden drills and Profile series 29.04 taper rotary instruments. After root-end resection and ultrasonic preparation, 48 root sections were randomly assigned to 4 groups of 12 teeth each and filled with a thick or thin mix of fast or regular set Super-EBA. Fast and regular set Super-EBA were mixed to a thick (1 scoop powder:1 drop liquid) or a thin (1 scoop powder:2 drops liquid) consistency. Positive and negative controls were used. Microleakage was assessed at 24 h, 72 h, 1 wk, 2 wk, 4 wk, 6 wk, and 8 wk using a fluid filtration system. There were no significant differences in the microleakage measured for any group at any of the time points evaluated. These results suggest that either fast or regular set Super-EBA mixed to various consistencies may be acceptable for root-end filling.

Analysis of Variance↗
PubMed1998

A comparison of amounts of apically extruded debris using handpiece-driven nickel-titanium instrument systems.

One hundred single-rooted teeth were instrumented with Lightspeed, Profile .04 Taper Series 29, and NT McXIM instruments according to the recommendations of the manufacturers, and Flex-R files using the balanced force technique. Groups were comparable with respect to average curvature, canal length, and major and minor foramen size. A standard amount of irrigant was used for each tooth. Apically extruded debris and irrigant were collected and weighed. Debris was desiccated before being weighed. There were no statistically significant differences among the four groups with respect to total extruded debris. The amount of extruded debris was positively correlated with the amount of irrigant extruded. Factors such as canal length, curvature, and foramen size did not affect the amount of debris extruded.

Analysis of Variance↗
PubMed1998

An evaluation of canal morphology at different levels of root resection in mandibular incisors.

One hundred randomly selected mandibular incisors were examined to assess the prevalence and location of two canals and to describe the canal anatomy that may be encountered during apical surgery. Sections of the root were cut at 1, 2, and 3 mm from the apex, simulating a 20-degree beveled surgical resection. The sections were digitally imaged at x 50 magnification, and canal dimensions were measured using imaging software. The prevalence of two canals was 2% at 1 mm, 0% at 2 mm, and 1% at 3 mm. At these levels in the roots, the canal was rarely divided by hard tooth structure. An isthmus of tissue was present 20% of the time at 1 mm, 30% at 2 mm, and 55% at 3 mm. Four distinct canal types were noted: (i) round, (ii) oval, (iii) long oval, and (iv) ribbon. In 75% of the teeth, the canal shapes varied from one level to the next. The more coronally the root-end resection was made, the more elongated the canal tended to become.

Dental Pulp Cavity↗
PubMed1996

Management of a maxillary canine with dens invaginatus and a vital pulp.

A case is presented that demonstrates successful management of a maxillary canine with dens invaginatus (Oehlers' type 3 invagination) with associated chronic periradicular periodontitis and a vital pulp. Debridement and obturation of the invaginated space resulted in resolution of the associated periradicular radiolucency. Pulp vitality was retained after endodontic treatment of the invagination.

Adolescent↗
PubMed1991

Thermally induced pulpalgia in endodontically treated teeth.

Two cases of thermally induced pulpalgia in teeth previously endodontically treated are presented. Reproduction of the patient's chief complaint was the key to identifying the teeth involved. In both cases, the pulpalgia was stimulated by heat. After locating and treating an unfilled canal, the teeth have remained asymptomatic. Possible explanations for this occurrence are discussed.

Adult↗
PubMed1991

Hemisection of a molar tooth in a dog: an alternative to total extraction.

Hemisection is a viable option to complete extraction in those situations where a portion of a tooth can still perform in health and function after the diseased portion has been removed. A case report is presented describing the hemisection of a mandibular first molar in a dog. Indications and contraindications for the procedure are outlined.

Animals↗
PubMed1990

The management of postbleaching cervical resorption.

Cervical resorption has been repeatedly associated with intracoronal bleaching procedures. This report reviews literature associated with postbleaching resorption, a case, and a rationale for management. We observed cervical resorption upon recall of an intracoronal bleaching case. It was successfully treated with a calcium hydroxide "recalcification" procedure. Twenty-three months later, no further resorption has been observed.

Adolescent↗
PubMed1989

The use of dentinal etching with endodontic bleaching procedures.

The removal of the smear layer from dentinal surfaces has been shown to increase significantly the permeability of dentin in both vital and endodontically treated teeth by opening the orifices of the dentinal tubules. This knowledge has led to the practice of acid etching the intracoronal dentin of endodontically treated teeth prior to nonvital bleaching procedures in order to increase the speed and effectiveness of the bleach. In this study extracted human teeth, which had been stained in vitro, were used to compare the effects of dentinal etching of the pulp chambers with no acid etching in conjunction with "walking bleach" procedures. In one experimental group, the pulp chambers were acid etched with 50% phosphoric acid for 1 min to remove the smear layer prior to insertion of the 30% hydrogen peroxide/sodium perborate bleaching agents. The second group had the same chamber preparation except the acid etching was deleted. Evaluators were unable to distinguish a significant difference between the effectiveness of the bleaching procedures in the two experimental groups.

Acid Etching, Dental↗