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PubMed1995

An in vivo evaluation of the ENDEX and RCM Mark II electronic apex locators in root canals with different contents.

The accuracy of many apex locators is affected by electrolytes including sodium hypochlorite. According to the manufacturer a new device, the ENDEX, overcomes this problem. The purpose of this study was to assess the accuracy of the ENDEX in comparison with a traditional device, the RCM Mark II. The lengths of 61 canals with various contents (vital pulp, necrotic pulp, pus/exudate, sodium hypochlorite, and water) were determined in vivo. Files were cemented within the canals at lengths determined by the ENDEX. The teeth were then radiographed and extracted, and the distance between the file tip and apical foramen was recorded. Derived readings for the RCM Mark II were compared with the actual ENDEX reading and corresponding radiograph. The results indicated that most of the file tips that were at the radiographic apex actually extended through the apical foramen, and canal content had a varying effect on each device. The overall accuracy of the ENDEX (71.7%) was higher than that of the RCM Mark II (43.5%) within 0.5 mm of the apical foramen. The ENDEX, unlike the RCM Mark II, proved accurate in the presence of sodium hypochlorite.

Chi-Square Distribution↗
PubMed1999

Re-innervation in the canine periodontal ligament of replanted teeth using an antibody to protein gene product 9.5: an immunohistochemical study.

The re-innervation process in the periodontal ligament of replanted canine teeth was examined by immunohistochemistry for protein gene product 9.5 (PGP 9.5), a general marker for neurons, and by electron microscopy. Within 1 week of replantation, the periodontal fibers had regenerated, filling the narrow spaces between the alveolar bone and the root surface around the cervical and apical regions. Near the root apex, however, no PGP 9.5-immunopositive nerve fibers were found in the regenerated periodontal ligament except for those in the alveolar half of the ligament. At 2 weeks after replantation, many nerve fibers positive for PGP 9.5 had ascended the periodontal ligament from the thick nerve bundles located near the root apex. Fine nerve endings showing complicated ramification were also present in the apical region. By 3 or 4 weeks after replantation, the vascular network was regenerated and principal periodontal fibers were re-established throughout the entire length of the periodontal ligament. The extensively ramified PGP 9.5-immunopositive structures had increased in thickness and density and showed characteristic tree-like profiles by 3 weeks. Electron microscopy confirmed that most of these structures were Ruffini-like endings, and demonstrated that such nerve terminals were almost regenerated by 4 weeks post-replantation. These results indicated that, in the periodontal ligament of replanted canine teeth, the regeneration of the nerve fibers including mechanosensory receptors first showed signs of regeneration by 2 weeks following tooth replantation and proceeded rapidly thereafter. Regeneration of the periodontal ligament including fiber architecture as well as vascular and neural elements was almost complete by 4 weeks after replantation.

Animals↗
PubMed1992

Three-dimensional observations of accessory canals in mature and developing rat molar teeth.

The structure, distribution and formation of accessory canals in the developing and mature molar teeth of rat mandibular jaws were investigated with scanning electron microscopy and with three-dimensional image analysis using serial light-microscopic sections. In the initial stage of the accessory canal formation, most of the canals appeared in the gaps of the epithelial root sheaths formed by their approaching each other in the initial stage of the root formation. However, some of the canals appeared in the slits which may be formed by the destruction of the epithelial root sheath in the root apex regions. When the gaps and slits were invaded by blood vessels, the regions surrounding the vessels did not mineralize but became accessory canals. Usually, an accessory canal with one blood vessel connected the periodontal ligament to the dental pulp; however, in some cases, the canals were broken off midway following the destruction of the vessels.

Animals↗
PubMed2001

Physical properties of root cementum: Part I. A new method for 3-dimensional evaluation.

Cementum is a nonuniform connective tissue that covers the roots of human teeth. Investigation of the physical properties of cementum may help in understanding or evaluating any possible connection to root resorption. A variety of engineering tests are available to investigate these properties. However, the thickness of the cementum layer varies, and this limits the applicability of these techniques in determining the physical properties of cementum. Hardness testing with Knoop and Vickers indentations overcame some of these limitations, but they prohibited the retrieval and retesting of the sample and therefore the testing was restricted to one area or section of the tooth. Another limiting factor with the existing techniques was the risk of artifacts related to the embedding material such as acrylic. A new method to investigate the physical properties of human premolar cementum was developed to obtain a 3-dimensional map of these properties with the Ultra Micro Indentation System (UMIS-2000; Commonwealth Scientific and Industrial Research Organization, Campbell, Australia). UMIS-2000 is a nano-indentation instrument for investigation of the properties of the near-surface region of materials. Premolars were harvested from orthodontic patients requiring extractions and then mounted on a newly designed surveyor that allowed sample retrieval and 3-dimensional rotation. This novel method enabled the quantitative testing of root surface cementum, on all 4 root surfaces, extending from the apex to the cementoenamel junction at 60 different sites.

Bicuspid↗
PubMed2000

A retrospective study of treatment provided in the primary and secondary care services for children attending a dental hospital following complicated crown fracture in the permanent dentition.

OBJECTIVES: To investigate treatment provision in primary and secondary dental care following complicated crown fracture of permanent teeth. DESIGN AND METHODS: Retrospective observational survey of dental records of all patients attending a dental hospital trauma clinic during a 2-year period with complicated crown fracture. RESULTS: Eighty children (70% male) aged 6-16 years (mean age 10.3 years) with 98 complicated crown fractures were identified. Of these children, 54% were seen for emergency treatment on the day of their injury, 75% within 48 h. Of the 98 injured teeth, 60% were seen initially in general dental practice but only 56% of these 59 cases were provided with emergency treatment in practice, the others being referred immediately to the trauma clinic for treatment. The main cause of fractures was transport, in particular, bicycles. Radiographs were available for 96 teeth; for the 43 open apex teeth, the definitive treatment was pulp capping (44% of cases) and pulpotomy (30%), with vitality maintained in five cases up to 4.8 years after trauma. The 53 closed apex cases were treated definitively with pulp capping (38%) and pulpectomy (36%) and six teeth had maintained their vitality up to 4.3 years after trauma. Sixty-seven per cent of the pulp caps and 47% of the 19 pulpotomies provided relied on a doubtful coronal seal. This was primarily due to the extensive use of a conventional glass ionomer cement as an emergency bandage. The use of an etched or bonded material at initial presentation extended the Median Survival Time for vitality in open apex teeth from 188 to 377 days and in closed apex teeth from 15 to 64 days. CONCLUSIONS: Emergency treatment of complicated crown fractures, particularly in primary care services is often inappropriate or inadequate with regard to emergency management of the exposed pulp and provision of a hermetic coronal seal.

Adolescent↗
PubMed1977

Immune neutrality of calf skin collagen gel used to stimulate revitalization in pulpless open apex teeth of rhesus monkeys.

A collagen mineral gel has recently been shown to stimulate revitalization of pulpless open apex teeth when syringed into debrided root canals. Experiments were conducted to examine possible stimulation of the immune system by the experimental procedure. Ring tests (interface precipitation analysis), Ouchterlony plates and hemagglutination tests on plasma samples taken from experimental rhesus monkeys throughout the healing process indicate a complete lack of humoral immune responsiveness to the injected collagen.

Animals↗
PubMed1988

Creative wire bending--the force system from step and V bends.

The force system produced by wires with steps and V bends was studied analytically by means of a small deflection mathematic analysis. Characteristic force relationships were found in both the step and the V bend. Step bands centrally placed between adjacent brackets produce unidirectional couples that are equal in magnitude. Along with these couples, vertical or horizontal forces are produced depending upon the plane of activation. Mesiodistal placement of step bends is not critical because very little alteration in force system occurs if a step is centered or positioned off center. V bends, on the other hand, are very sensitive to the positioning mesiodistally of the apex of the V. If the apex of the V bend is placed on center, equal and opposite couples are produced. As the V-bend apex is moved off center, predictable combinations of moments and forces are created. A method for determination of the relative force system is described that allows for simple interpretation and prediction of the force system from a V bend. The clinical applications of these data and a rational basis for wire bending are presented based on the producing of a desired force system.

Biomechanical Phenomena↗
PubMed1990

An evaluation of the Apex Locator Endocater.

The purpose of this study was to relate the relationship of the apical constriction to the anatomical apex and to determine the ability of the Endocater (Hygenic Corp., Akron, OH), using commercially bonded coated probes to locate the position of the apical constriction, in permanent teeth that were intact and had not been subjected to previous endodontic manipulation. Using local anesthesia and rubber dam isolation, conventional access cavities were prepared at ultra high speed with water coolant in teeth treatment planned for extraction. The Endocater was used to determine the working length. The probes were sealed in place with autopolymerizing composite resin and the teeth extracted. The teeth were sectioned buccolingually, and the position of the probe in relation to the anatomical apex and apical constriction was measured with the use of an ocular microscope. In 17.1% of the canals, the probes bound in the coronal portion of the canals and would not reach the apical portion of the root. In those teeth in which the probes reached the apical portion of the root, the Endocater was able to locate the apical constriction within 0.5 mm in 93.4% of the canals.

Dental Pulp Cavity↗
PubMed1997

Coronal leakage of obturated root canals after long-term storage using a polymicrobial marker.

This in vitro study investigated the effect of long-term storage on the coronal leakage of a microbial marker on teeth root filled with lateral condensation of cold gutta-percha and one of two sealers. Sixty single-rooted teeth were prepared chemomechanically to a size 40 master apical file. The teeth were divided into two groups of 20 teeth each and obturated with gutta-percha using either Apexit or Tubliseal EWT sealer. The teeth were stored for 6 months in artificial saliva and tested for leakage using a marker consisting of S. sanguis and P. intermedia. The teeth were checked for bacterial leakage daily for 90 days. All positive control teeth leaked after 24 h, while the negative control teeth remained uncontaminated throughout the test period. Leakage reached the apex through the experimental teeth at the earliest at 17 days and at latest at 88 days. Fifty percent and 70% of the specimens of the Apexit and Tubliseal EWT groups respectively showed leakage at 90 days. There was no statistically significant difference (p > 0.05) between the two groups.

Calcium Hydroxide↗
PubMed1993

Accuracy of the Endex with variations in canal irrigants and foramen size.

Several electronic apex locators (EALs) are currently available. The manufacturer of a new device, the Endex, claims that it is accurate regardless of canal conditions. This study compared the accuracy of the Endex with that of the Exact-a-pex, the Sono-Explorer Mark III, and the Neosono-D SE as to the effects of fluids in the canal and variation in foramen size. Sixty extracted single-canaled teeth were divided into two groups (narrow and wide foramina), depending on whether the apical foramina permitted the tip of a #30 K file to pass through. An in vitro model was used, in which teeth were fitted in test tubes with the roots immersed in 1% agar in phosphate-buffered saline. Root canal lengths were measured in dry canals, then with ethanol, Xylocaine, and sodium hypochlorite in the canals by each electronic apex locator. These lengths were compared with those of the actual root canal lengths. No significant differences were noted among the instruments in dry canals regardless of the foramen size. The endex was generally superior to the other instruments examined in canals containing conductive fluids, especially where the apical foramen was widened.

Chi-Square Distribution↗
PubMed1989

Dentinal tubules at the root ends of apicected teeth: a scanning electron microscopic study.

Two groups of teeth, one of which contained teeth of known age, were examined by scanning electron microscopy to ascertain the presence of a potential pathway for leakage at the root ends of apicected teeth. At a point approximately 3 mm from the apex, a level chosen as being typical for apicectomy, and half-way between the root canal and the dentine-cementum junction, there were found to be, on average, 27,000 tubules per mm2. Older teeth also displayed large numbers of tubules. Close to the dentine-cementum junction, an area which may communicate with the root canal even in the presence of a retrograde root filling, an average of 13,000 tubules per mm2 were found.

Dental Cementum↗
PubMed1993

Morphology of the root canal wall and arrangement of underlying dentinal tubules.

The morphology of the root canal wall and the arrangement of the dentinal tubules underlying it were investigated in this study. Fifty clinically sound single-rooted human teeth were cut for longitudinal and transverse sections. After dissolving the organic components and removing the smear layer, the specimens were prepared for scanning electron microscopy. In the upper root level, semiglobular calcospherites were present on the canal wall and a convergent arrangement of the dentinal tubules was found on the transverse sections. At the mid-root level, an irregular area of calcification comprising of compressed calcospherites began to appear on the proximal wall and increased towards the apex. The transverse sections showed the crowding and convoluted arrangement of the dentinal tubules near the canal wall, in the proximal area. A correlation was noticed between the irregular calcification on the wall and a convoluted tubular arrangement below the wall. These features were common in most of the specimens. This irregular secondary dentine does not appear to be pathological but physiological: associated with the normal ageing of the root.

Dental Pulp Cavity↗
PubMed1991

Nonionizing method of locating the apical constriction (minor foramen) in root canals.

The electronic method was evaluated as to its accuracy when used to determine the position of the apical constriction (minor foramen) in root canals. There were 39 vital and 8 nonvital teeth for a total of 47 specimens from 22 patients. The specimens were prepared with a Buehler Isomet bone saw to a thickness of 500 microns. Distances were measured and recorded with the use of a Bioquant II image analysis system. The electronic method appeared to measure a mean value of 0.2 mm coronal to the cemetodentinal junction in 47 canals where the apex locator was set at a reference setting of 40. When a frequency curve was plotted, it showed that the probability of being within 0.76 mm (1 SD) of the cementodentinal junction was 68%. This appears to correlate to where Kuttler indicated the minor constriction to be located. These devices seem to offer a unique method to locate the apical constriction and thus to ensure proper working length while reducing ionizing radiation.

Aged↗
PubMed1998

Determining the temperature rise in the pulp and at the root surface during pin hole drilling and placing of dentine pins.

The purpose of this study was to determine the temperature at specific sites in the pulp and periodontium during consecutive dentine pin placement. Twenty extracted human permanent lower first molar teeth were used, cut flat at a depth of 2 mm from the occlusal surface and Titanium pins of medium size placed 1 mm inside the dentinoenamel junction. The middle of the mesial root, mesial apex and the bifurcation were sites of evaluation of the temperature of the periodontium using a thermocouple. Measurements of the temperature change in the pulp chamber were also performed. Consecutive hole drilling and placing of four pins caused a statistically significant increase in temperature in the pulp chamber, but failed to show a significant temperature rise at the root surface. The maximum temperature rises were below those reported to threaten pulpal and periodontal health.

Analysis of Variance↗
PubMed2006

Three-dimensional bone microstructures of the mandibular angle using micro-CT and finite element analysis: relationship between partially impacted mandibular third molars and angle fractures.

The mandibular angle is one of the areas of the mandible that are prone to bone fractures, and the presence of an impacted third molar has been found to be associated with increased risk of angle fractures. The factors involved in bone fractures are the amount and direction of load, and the biomechanical and anatomical properties of bone. In the present study, micro-focused X-ray computed tomography was performed to observe and analyze the three-dimensional (3D) bone microstructure of the mandibular angle, and finite element analysis was conducted to examine the relationship between angle fractures and the presence or absence of mandibular third molars. 3D bone microstructure showed no marked difference between mandibles with and without third molars. Finite element analysis showed that, in the mandible with a third molar, stress was concentrated around the root apex of the third molar, and was transmitted in a direction matching the clinical findings of angle fractures. The results obtained in this study suggest that the presence of an impacted third molar changes the concentration and transmission of stress in the mandible, thus increasing the risk of an angle fracture.

Anisotropy↗
PubMed1976

A study of the anterior portion of the palate as it relates to orthodontic therapy.

1. The anterior portion of the palate does not appear to move lingually as orthodontic forces move incisor teeth lingually. Although the alveolar bone directly supporting the teeth can be moved distally (and elongated), it does not appear possible to move the apex of the root more distally than the pretreatment position of the palatal plate. Thus, there appears to be an anatomic limitation to the distal movement of maxillary incisor teeth. 2. When incisor teeth are moved distally within the boundaries of the present alveolar process, the supporting bone does not remodel to the roots' new position; when a root which was initially positioned nearer the labial alveolar plate is moved distally against the palatal plate, there was observed no adaptation in the bone to have the root once again located near the labial alveolar plate, the root remained stable against the palatal plate. 3. When great distal movement of incisor teeth results in an alteration in position of the supporting alveolar bone, remodeling of the bone maintains a relatively constant labiolingual width of this alveolar bone. The new position of the tooth and supporting bone appears to be stable. 4. The scanty metallic implant evidence would seem to support histologic observations that alveolar processes are remodeled by apposition of bone on the cortical plate toward which the tooth is moving and resorption of the cortical plate away from which the tooth is moving. 5. There does not appear to be a statistically significant correlation between posterior facial measurements (SNMP) and the labiolingual width of the anterior palate.

Adolescent↗
PubMed1989

[Follow-up investigation of the effect of Ca(OH)2 on the teeth with necrotic pulps and immature root development and surrounding periodontal tissues].

In this study Ca(OH)2 + distilled water was applied to the traumatized necrotic incisor teeth with immature root development. After necessary mechanical and chemical root canal disinfection the paste was applied to 13 teeth of 9 patients. Periodontologic problems in vestibule gingiva of the teeth prior to the treatment doubted if the primary lesion was the necrotic pulp or periodontal infection. After control periods (6 weeks, 3 months, 6,9,12,18,24 months) the cases were evaluated roentgenographically whether the apical closure was obtained. After observation of calcified tissue in the apex the canals were filled with sectioned warm gutta percha with vertical condensation. All the cases were successful except one and after treatment restorations were performed. In case all the patients experienced periodontologic problems from the teeth prior to treatment, after endodontic treatments and application of Ca(OH)2 to the canal, healing of periodontal tissues were also observed. This finding shows the importance of differential diagnose of periodontal problems caused by pulpal necrosis.

Calcium Hydroxide↗
PubMed2004

Revascularization of immature permanent teeth with apical periodontitis: new treatment protocol?

A new technique is presented to revascularize immature permanent teeth with apical periodontitis. The canal is disinfected with copious irrigation and a combination of three antibiotics. After the disinfection protocol is complete, the apex is mechanically irritated to initiate bleeding into the canal to produce a blood clot to the level of the cemento-enamel junction. The double seal of the coronal access is then made. In this case, the combination of a disinfected canal, a matrix into which new tissue could grow, and an effective coronal seal appears to have produced the environment necessary for successful revascularization.

Bicuspid↗