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PubMed1991

[Study of properties of electrical root canal length measuring instruments].

Six electrical instruments for locating the apex during endodontic treatment were tested in a laboratory investigation about currency, frequency and scale. Further we looked, whether all instruments show coincidence in the apex point. There are great differences in currency, frequency and scale (apex point). The reproducibility and the precision of an apex locator--at the time--depends an many factors and thus indication seems to be very limited.

Dental Pulp Cavity↗
PubMed2005

Clinical application of stereolithographic surgical guides for implant placement: preliminary results.

BACKGROUND: The success of implant-supported restorations requires detailed treatment planning, which includes the construction of a surgical guide. Recently, computer-aided rapid prototyping has been developed to construct surgical guides in an attempt to improve the precision of implant placement. The aim of the present study was to evaluate the match between the positions and axes of the planned and placed implants when a stereolithographic surgical guide is employed. METHODS: Six surgical guides used in four patients (three women, one man; age from 23 to 65 years old) were included in the study and 21 implants were placed. A radiographic template was fabricated and computer-assisted tomography (CT) was performed. The virtual implants were placed in the resulting 3-dimensional image. Using a stereolithographic machine, liquid polymer was injected and laser-cured according to the CT image data with the planned implants, generating three surgical guides, with increasing tube diameters corresponding to each twist drill diameter (2.2, 3.2, and 4.0 mm), for each surgical area. During the implant operation, the surgical guide was placed on the jawbone and/or the teeth. After surgery, a new CT scan was taken. Software was used to fuse the images of planned and placed implants, and the locations and axes were compared. RESULTS: On average, the match between the planned and the placed implant axes was within 7.25 degrees +/- 2.67 degrees ; the differences in distance between the planned and placed positions at the implant shoulder were 1.45 +/- 1.42 mm, and 2.99 +/- 1.77 mm at the implant apex. In all patients, a greater distance was found between the planned and placed positions at the implant apex than at the implant head. CONCLUSIONS: Clinical data suggest that computer-aided rapid prototyping of surgical guides may be useful in implant placement. However, the technique requires improvement to provide better stability of the guide during the surgery, in cases of unilateral bone-supported and non-tooth-supported guides. Further clinical studies, using greater number of patients, are necessary to evaluate the real impact of the stereolithographic surgical guide on implant therapy.

Adult↗
PubMed2003

Effect of X-ray beam angulation and intraradicular contrast medium on radiographic interpretation of lower first molar root canal anatomy.

AIMS: To compare evaluator radiographic interpretation of noncontrasted and contrasted root canal anatomy on radiographs taken at a 0 or 30 degrees mesial angle to the orthoradial orientation. METHODOLOGY: Pulp tissue was removed from 20 mandibular first molar teeth using NaOCl irrigation and hand files. Standardized radiographs at 0 and 30 degrees angulation were obtained of each tooth positioned in a dried mandible. Contrast medium (iohexol) was injected passively into the canals and a second pair of corresponding radiographs was obtained. A third pair of radiographs was taken after infusing canals under vacuum with contrast medium. Using set criteria, three evaluators assessed the canal anatomy of the mesial root on radiographs: (i) the number of visible canals, (ii) whether the canal(s) was visible along the entire length of the root, (iii) the location of the canal terminus in relation to the radiographic apex, (iv) configuration of canal(s), (v) level of multiple canals merging and (vi) the presence of lateral canals. The teeth were then cleared for visual assessment. The data were compared using logistic regression and the intra- and interevaluator reliability assessed with the Kappa test. RESULTS: Noncontrasted 0 degrees images were significantly better (P < 0.05) than noncontrasted 30 degrees images for detecting the number of visible canals, whether the canal(s) was visible along the entire length of the root, the location of the canal terminus in relation to the radiographic apex and level of multiple canals merging. The 0 degrees images contrasted by vacuum or passive injection were significantly better (P < 0.05) than 30 degrees images only for assessing whether the canal(s) was visible along the entire length of the root, whilst the 0 degrees image contrasted by passive injection was also better (P < 0.05) at assessing the location of the canal terminus in relation to the radiographic apex. At 30 degrees, contrast medium passively or vacuum introduced improved (P < 0.05) the detection of the number of visible canals, whether the canal(s) was visible along the entire length of the root and configuration of canal(s), whilst vacuum also improved (P < 0.05) the location of the canal terminus in relation to the radiographic apex. Overall, there was no significant difference (P > 0.05) between images contrasted by passive injection or vacuum. CONCLUSIONS: Under the conditions of this study, conventional radiographs taken at a 0 degrees orientation provided more information than 30 degrees radiographs. Contrast medium improved radiographic interpretation of canal anatomy, especially when used with 30 degrees radiographs.

Contrast Media↗
PubMed2005

Histological and immunohistochemical studies of tissue engineered odontogenesis.

The successful regeneration of complex tooth structures based on tissue-engineering principles was recently reported. The process of this regeneration, however, remains poorly characterized. In this study, we have used histochemistry to examine the regeneration process of tissue engineered teeth in order to determine the cell types that give rise to these engineered tooth structures. Porcine third molar tooth buds were dissociated into single-cell suspensions and seeded onto a biodegradable polyglycolic acid polymer scaffold. Following varying periods of growth in rat hosts, the specimens were evaluated by histology and immunohistochemistry. Aggregates of epithelial cells were first observed 4-6 weeks after implantation. These aggregates assumed three different shapes: a natural tooth germ-like shape, a circular shape, or a bilayer-bundle. Based on the structure of the stellate reticulum in the dental epithelium, the circular and bilayer-bundle aggregates could be clearly classified into two types: one with extensively developed stellate reticulum, and the other with negligible stellate reticulum. The epithelial cells in the circular aggregates differentiated into ameloblasts. The continuous bilayer bundles eventually formed the epithelial sheath, and dentin tissue was evident at the apex of these bundles. Finally, enamel-covered dentin and cementum-covered dentin formed, a process most likely mediated by epithelial-mesenchymal interaction. These results suggest that the development of these engineered teeth closely parallels that of natural odontogenesis derived from the immature epithelial and mesenchymal cells.

Ameloblasts↗
PubMed1990

An SEM investigation of the mesiolingual canal in human maxillary first and second molars.

The mesiolingual orifices of 21 maxillary first molars and 37 maxillary second molars were examined with the scanning electron microscope. The mesiobuccal roots of these teeth were also typed by means of a clearing technique. The results demonstrated that 90% of first molars and 70% of second molars had two canals in the mesiobuccal root. Type 3 canal systems occurred in 33% of first molars and 35% of second molars. Eighty-one percent of first molars and 59% of second molars had a separate mesiolingual canal orifice. The mean diameter of the mesiolingual orifice was 0.49 mm in first molars and 0.42 mm in second molars. The mean distance of the mesiolingual orifice from the mesiobuccal orifice was 2.31 mm in first molars and 2.06 mm in second molars. In type 3 roots, the average distance of the mesiolingual foramen to the anatomic apex was 2.0 mm for first molars and 1.45 mm for second molars.

Adolescent↗
PubMed2007

Mesial migration effect on root morphology of mandibular third molars.

OBJECTIVE: To test the hypothesis that there is a relationship between forward mandibular third molar migration and root curvature of the mandibular third molars. MATERIALS AND METHODS: The study is comprised of 64 patients who had a history of unilateral mandibular first molar extraction before 16 years of age with no other missing teeth or prosthetic restorations in the mandible. The extraction space was fully or partly closed. The mean remaining space was 1.1 +/- 0.41 mm. The root angles for the mesial and distal roots of the mandibular third molars were measured on the panoramic radiographs by calculating the differences between the angle formed by the long axis drawn perpendicular to the occlusal plane of the crown of mandibular third molar and the central line of the lower one ninth of the root through the root apex. The differences between the extracted and nonextracted sides for mesial and distal roots were analyzed using a paired sample t-test. RESULTS: Both mesial and distal roots were approximately 8 degrees more vertical on the extraction sides than on the nonextraction sides. The differences were statistically significant. CONCLUSION: Mesial tooth migration of mandibular third molars reduces the amount of root curvature developing on this tooth.

Adolescent↗
PubMed1989

The labial endodontic access: a rational treatment approach in anterior teeth.

Labial endodontic access is an alternative to the conventional lingual endodontic access in permanent teeth. The labial approach facilitates visibility and provides direct access to the root apex. Current restorative procedures offer improved methods to overcome the esthetic impairment resulting from this approach. Labial access is especially beneficial for patients with limited mandibular opening. Other indications are in Angle's class II division 2 dentitions or in teeth with resin-bonded cast restorations. Anatomic studies for the single tooth that corroborate the labial endodontic approach are reviewed.

Cuspid↗
PubMed2003

Removal of organic debris from bovine dentin shavings.

A common problem with root canal failures is chronic inflammation at the apex caused by overfilling of root canal materials. Dentin filings have been suggested as an apical plug to create a biocompatible barrier between the filling material and the periapical tissue. Unfortunately residual organic material, such as pulp remnants or bacteria, still may be part of the filings. Dentin filings removed from the tooth, cleaned, and then used to form a barrier might serve as an effective barrier. The purpose of this study was to evaluate methods of cleaning dentin of organic debris. NaOCl, sodium dodecyl sulfate, and 1% Triton X-100 were used to treat dentin shavings and were evaluated by a micro bicinchoninic acid protein analysis assay. Two series of experiments were performed. One compared the effect of temperature while using phosphate-buffered saline as a control and the second compared exposure times. The percentage of protein extracted from dentin samples increased with temperature. Sodium hypochlorite at room temperature extracted 24.6%, NaOCl at 37 degrees C extracted 26.9%, and NaOCl at 70 degrees C extracted 33.9%. Only NaOCl at 37 degrees C and 70 degrees C showed statistically significant differences from phosphate-buffered saline at room temperature with p-values of 0.028 and 0.019, respectively. The exposure time series showed a difference between a phosphate-buffered saline solution and 6.25% NaOCl. NaOCl removed approximately 90% of protein compared with 60% for the phosphate-buffered saline. A 10-min exposure to 70 degrees C 6.25% NaOCl may be an efficient means of removing organic material from dentin shavings.

Animals↗
PubMed1985

Adaptation of a prefabricated post to dentin.

The adaptation of an inventive prefabricated post and core to dentin is presented as part of a series of research reports. The authors suggest that the imaginative design of the split shaft and its telescoping or collapsible apex reduces stress and the finely threaded shaft improves retention.

Crowns↗
PubMed1982

Diffusion of carbon-14-labeled formocresol and glutaraldehyde in tooth structures.

14C-Formocresol and 14C-glutaraldehyde were placed in the root canals of freshly extracted human teeth. The outward diffusion of labeled aldehydes was then measured and autoradiograms of cross-sections taken. No diffusion of glutaraldehyde was detectable within 72 hours, whereas there was a rapidly increasing outflow of formocresol during the same period. In a separate group normal root canal treatment was completed until 2 mm. short of the roentgenologic apex with glutaraldehyde as an irrigant. The walls of the root canals of some of the specimens were examined with electron microscopy and the outflow of 14C-formocresol which was later placed in some specimens was counted. The use of glutaraldehyde as an irrigant resulted in closure of the apical third of the root canal as indicated by the absence of 14C-formocresol diffusion.

Aldehydes↗
PubMedDate not supplied

Endodontic working length determination--where does it end?

Obtaining a correct working length is critical to the success of endodontic therapy. Failure to identify this crucial measurement can result in untoward treatment outcomes, which may include increased patient discomfort, possible infection or cyst development, and extrusion or intra-canal medication into the periradicular tissue. This article reviews the classical and current terminology, philosophies, and techniques that are used at present to determine endodontic working length accurately, and describes their clinical application. Recent clinical advances such as the electronic apex locator, direct digital radiography, and the surgical operating microscope also are discussed.

Adult↗
PubMed1983

Clinical considerations in the diagnosis and treatment of intra-alveolar root fractures.

Clinical and radiographic data collected from the 14 cases of intra-alveolar root-fractures, with follow-ups of one to 25 years, complement the findings of other investigators in that the prognosis of the endodontium is extremely favorable. A survey of reports indicate that 75% to 80% of the pulps in intra-alveolar root fractures recover with no need of any endodontic therapy. Furthermore, pulpal pain is seldom encountered. Although the electric pulp tester is considered an important diagnostic tool, it does have limitations. The significance of the negative response is questionable, especially in young, undeveloped teeth with open apexes. The failure to respond to the tester may be attributed to a high electrical impedance. As nociceptor nerve fibers are last to develop, failure to respond to the tester in young teeth may give a false signal of pulp necrosis. Traumatized vital teeth often give an initial negative response, as does a tooth with rapid dentin deposition. Fracture detection can be increased by taking X rays from more than one angle. Radiolucent areas occur in the region of the root fracture more readily than in the periapical region, in a ratio of 7 to 1. Variations in angulations can give false impressions of complete dentinal union and complete or incomplete calcification of the pulpal space and an illusion of a comminuted fracture. The latter seldom occur in intra-alveolar root fractures. Furthermore, the apparent obliteration of the canal and pulp chamber, as seen on the radiograph, does not imply total obliteration with calcific tissue. The root canals are most often patent and negotiable.(ABSTRACT TRUNCATED AT 250 WORDS)

Dental Pulp↗
PubMed2002

FGF10 maintains stem cell compartment in developing mouse incisors.

Mouse incisors are regenerative tissues that grow continuously throughout life. The renewal of dental epithelium-producing enamel matrix and/or induction of dentin formation by mesenchymal cells is performed by stem cells that reside in cervical loop of the incisor apex. However, little is known about the mechanisms of stem cell compartment formation. Recently, a mouse incisor was used as a model to show that fibroblast growth factor (FGF) 10 regulates mitogenesis and fate decision of adult stem cells. To further illustrate the role of FGF10 in the formation of the stem cell compartment during tooth organogenesis, we have analyzed incisor development in Fgf10-deficient mice and have examined the effects of neutralizing anti-FGF10 antibody on the developing incisors in organ cultures. The incisor germs of FGF10-null mice proceeded to cap stage normally. However, at a later stage, the cervical loop was not formed. We found that the absence of the cervical loop was due to a divergence in Fgf10 and Fgf3 expression patterns at E16. Furthermore, we estimated the growth of dental epithelium from incisor explants of FGF10-null mice by organ culture. The dental epithelium of FGF10-null mice showed limited growth, although the epithelium of wild-type mice appeared to grow normally. In other experiments, a functional disorder of FGF10, caused by a neutralizing anti-FGF10 antibody, induced apoptosis in the cervical loop of developing mouse incisor cultures. However, recombinant human FGF10 protein rescued the cervical loop from apoptosis. Taken together, these results suggest that FGF10 is a survival factor that maintains the stem cell population in developing incisor germs.

Animals↗
PubMed2006

Factors affecting treatment outcomes following complicated crown fractures managed in primary and secondary care.

The aims of this retrospective observational study were to determine the factors which affect treatment provision and the Median Survival Time (MST) for maintenance of tooth vitality following complicated crown fracture. The survey was carried out for patients treated at Newcastle Dental Hospital (NDH) according to departmental guidelines over a 2-year period following the introduction of a new protocol for management of these types of injuries. Seventy-three cases of complicated crown fracture were identified in 69 children with a mean age of 10.3 years (SD = 2.5 years). Seventy-one percent of the fractures occurred in males (M:F ratio was 2.5:1). Fifty-one percent of the complicated crown fractures were in immature teeth. Of the 73 traumatised teeth, 45% presented initially in general dental practice (GDP), 37% at the dental hospital and 8% at local accident and emergency departments with the remaining 10% seen at other or unrecorded locations. Of the 41 fractures, which presented initially at a location other than the dental hospital, 38% were referred to the dental hospital without the provision of an emergency pulp bandage. The overall definitive treatments provided for the 37 open apex teeth included pulp cap (19%), partial pulpotomy (32%), cervical pulpotomy (8%) and pulpectomy (35%), while for the 36 closed apex teeth it was pulp cap (28%), pulpotomy (11%), and pulpectomy (61%). Of the 30 teeth, which underwent vital pulp therapy (18 open and 12 closed apex), the MST for the 15 teeth treated with pulp caps was 1460 days (95% CI: 1067, 1853) while for the 15 teeth treated with pulpotomies it was 1375 days (95% CI: 964, 1786). There was no statistically significant difference in the MST between teeth treated with pulp caps and pulpotomies. In conclusion, the proportion of patients referred to secondary care with complicated crown fractures without provision of a pulp bandage is of some concern. More conservative treatment of closed apex teeth sustaining complicated crown fractures, utilizing vital pulp therapy techniques would appear to be appropriate.

Adolescent↗
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↗
PubMed1992

[The use of orthodontic goniometry to study apical expansion, using Pr. Planas' method: neuro-occlusal rehabilitation].

In this work, the method of orthodontic goniometry is used, which is a simple technique and not expensive, that allows us to determine the apical expansion in the studied models. 42 patients are studied by means of the techniques of Neuro-Occlusal Rehabilitation. We reach by this method expansion to the level of the apex as far as 12 mm in the lower arch and 11 mm in the upper arch. A simple statistic analysis is made which shows an average of expansions of 7.76 mm at crown level of the upper arch and 8.11 mm at apex level; at the crown level of lower arch we get 6.43 mm and apex level 5.8 mm. We think these results are interesting and they should make us study in depth the Neuro-Occlusal Rehabilitation and its principles.

Cephalometry↗
PubMed2005

[The effect of maxillary and mandibular lip bumper on teeth and dental arch in late mixed dentition].

PURPOSE: To study the effect of maxillary and mandibular lip bumper on tooth and dental arch in late mixed dentition. METHODS: Twelve subjects with mild or moderate crowding were selected. They were treated with maxillary and mandibular lip bumper for eight months. Analysis of cephalometrics and model measurements were done before and after treatment and paired t test were performed respectively for their changes. RESULTS: After treatment, SNA and SNB increased by 1.02 degrees and 0.97 degrees (P<0.05). Upper and lower incisor both had controlled tipping movement. The crown of incisor moved mesially and had root apex were fixed relatively. The center of rotation was close to root apex. The upper and lower molar moved differently. Upper molar was upright distally and the center of rotation was close to the crown. However, the lower molar tipped distally and the center of rotation was close to the center of resistance.The width between the first molars and length of maxillary dental arch increased by 4.12 mm and 5.09 mm (P<0.01). The width between the first molars and length of mandibular dental arch increased by 4.07 mm and 6.86 mm (P<0.01) CONCLUSION: Clinical application of lip bumper could cause transverse and vertical changes in dental arch ,which help to decrease or remove crowding.

Dental Arch↗