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PubMedDate not supplied

Inhibition of pure cultures of oral bacteria by root canal filling materials.

This study compared the antimicrobial effectiveness of nine dental materials and a negative control agent against 21 strains or species of bacteria using an agar diffusion assay. The materials were: 1. Camphorated parachlorophenol mixed with calcium hydroxide (CPC + Ca(OH)2). 2. CPC mixed with zinc oxide (CPC + ZnO). 3. Formocresol mixed with zinc oxide and eugenol (FC + ZOE). 4. Chlorhexidine mixed with ZOE (CHX + ZOE). 5. Kri paste. 6. ZOE. 7. Zinc oxide mixed with sterile water (ZnO + H2O). 8. Calcium hydroxide mixed with sterile water (Ca(OH)2 + H2O). 9. Vitapex. 10. Vaseline (control). The test bacteria represented species commonly isolated from nonvital primary and permanent tooth root canals. The antimicrobial effectiveness of the materials was divided into five groups based on the diameters of the zones of inhibition against all test bacteria and distribution of the data. All materials except Vaseline showed antimicrobial activity against some of the 21 organisms. Generally, all materials inhibited gram-negative anaerobic bacteria more effectively than aerotolerant gram-negative or gram-positive bacteria. Materials containing CPC or FC (except Kri paste) produced strong or medium strong inhibition against most bacteria. CHX + ZOE, Kri paste, ZnO + H2O, and ZOE inhibited all or most bacteria, but to lesser extent than CPC + Ca(OH)2, CPC + ZnO, or FC + ZOE. Ca(OH)2 + H2O, Vitapex, and Vaseline generally were nonihibitory. The findings should allow a comparative evaluation of antimicrobial effectiveness to be made of materials commonly used in pulpectomy procedures with primary teeth.

Anti-Infective Agents, Local↗
PubMed2005

Radiodensity evaluation of seven root post systems.

PURPOSE: To compare through digital radiographic analysis the radiodensity levels of seven prefabricated post systems inserted in root canals of bovine extracted incisors. METHODS: 21 bovine teeth were cut 15 mm from the apical limit. The canals were prepared according to the manufacturer's instructions using specific bur of each post system analyzed: three metallic posts: Flexi-Flange, Radix-Anker, and FKG post; one zirconium ceramic post: Cosmopost; one carbon fiber post: C-Post; one carbon fiber post system covered with quartz fiber: AEsthetic Post; and one glass fiber reinforced post: FibreKor Post. Root tooth digital analyses were made with Digora system with and without the insertion of post. Their variations were obtained subtracting radiodensity of the post from radiodensity of the root canal, in cervical, medium, and apical thirds of the root canal. Two-way ANOVA and Tukey test (P< 0.05) were used to analyze the data. RESULTS: This study showed that the radiopacity of post systems is dependent on their composition. Statistical differences were found among radiodensity levels in apical third, medium and cervical thirds for all post systems inside the root canals. Statistical differences were also found among the post systems: ceramic posts showed the highest radiodensity level, followed by metallic posts, carbon fiber posts, glass fiber posts, and the carbon fiber post covered with quartz fiber. These results indicate that biomechanical post systems have low radiodensity levels.

Absorptiometry, Photon↗
PubMed2006

A new method for the automated age-at-death evaluation by tooth-cementum annulation (TCA).

A valid age at death estimation is required in historical and also forensic anthropology. Tooth cementum annulation (TCA) is a method for age at death estimation of adult individuals. The method is based on light microscope images taken from tooth-root cross sections. The age is then estimated by manually counting the cementum incremental lines and adding this to the chronological age at the assumed point of tooth eruption. Manual line counting, however, is time consuming, potentially subjective and the number of individual counts is insufficient for statistical evaluations. Software developed for the automated evaluation of TCA images, that uses Fourier analysis and algorithms for image analysis and pattern recognition is presented here. It involves "line-by-line" scanning and the counting of gray scale peaks within a selected region-of-interest (ROI). Each scanning process of a particular ROI yields up to 400 counts that are subsequently statistically evaluated. This simple and time saving program seeks to substitute manual counting and supply consistent and reproducible results as well as reduce the demand of human error by eliminating unavoidable factors such as subjectivity and fatigue.

Age Determination by Teeth↗
PubMed1989

The blood flow in the periodontal ligament regulated by the sympathetic and sensory nerves in the cat.

This study was carried out to investigate the nervous control of the blood flow in the periodontal ligament measured by laser Doppler flowmeter. Ten adult cats were anesthetized with pentobarbital sodium (initial dose of 30 mg/kg, i.v. and maintenance dose of 5 mg/kg, i.v.). After enucleating the left eye ball, the superior alveolar nerve was exposed. The bone overlying the labial aspect of the left maxillary canine tooth root was pared away until a transparent layer of bone was left covering the periodontal ligament. A laser light from a probe of the flowmeter fixed at the tooth was beamed through the thinned bone. Three different patterns of responses were observed following the electrical stimulation of the distal end of the cut superior alveolar nerve: an increasing, a decreasing and a biphasic change of blood flow. The application of capsaicin onto the superior alveolar nerve reduced the response of blood flow increase but had no effect on the response of blood flow decrease. On the other hand, the response of blood flow decrease was completely inhibited by the pretreatment with phentolamine while the response of blood flow increase was not affected. The present results suggest that blood flow in the periodontal ligament of cats is controlled by sympathetic alpha-adrenergic fibers for vasoconstriction and by sensory fibers for vasodilation.

Animals↗
PubMed1995

Orthodontic tooth movement and root resorption with special reference to force magnitude and duration. A clinical and histological investigation in adolescents.

The purpose of orthodontic treatment is to move teeth as efficiently as possible with least damage to teeth and their supporting tissues. Root resorption may occur as an unwanted side effect and may in some instances jeopardize an otherwise successful treatment. The general aim of this series of clinical investigations was to study the association between applied force, achieved tooth movement and related root resorptions. In 144 adolescents, the maxillary first or second premolar was buccally moved with a fixed orthodontic appliance. The variables studied were duration, magnitude and type of force. Moreover, both the occurrence of orthodontically induced root resorptions and the reparative potential were investigated in histological preparations of the teeth. When a continuous force of a clinically relevant magnitude (50 cN approximately 50 g) was applied, tooth movement increased gradually over time. Root resorptions were recorded in all test teeth but 4 (93%). After 3 weeks a few teeth revealed root resorptions extending half way to the pulp or more in the apical third of the root. No association was found between root resorptions and tooth movement. Doubling the force magnitude (100 cN approximately 100 g) affected neither the tooth movement nor the severity of root resorptions. However, when the force was increased 4 times (200 cN approximately 200 g), tooth movement increased 50% but still with no significant increase in the occurrence or severity of root resorptions. Tooth movement was achieved more efficiently with a continuous force than with an interrupted type of force of the same magnitude (50 cN). Root resorptions, though, did not seem to be affected differently by the two types of forces. Reduction of all types of applied forces was considerable, about 25-30%, already within one week. Repair with secondary cementum was recorded almost 3 times more often after 8 weeks (75%) of retention than after 1 week (28%). Irrespective of magnitude and type of force, large individual variations were observed regarding tooth movements and root resorptions as well as their reparative potential. The possible clinical consequences of the results obtained are discussed with regard to cost-benefit effects, convenience to the patient and risk of complications.

Adolescent↗
PubMed1996

Rigidity and retention of carbon fibre versus stainless steel root canal posts.

Two of the main requirements of a root canal post are that it is rigid so as to resist flexing under functional load, and that it is well retained in the root. This study compared these properties in two different 1-mm diameter root canal posts--smooth carbon fibre posts (Endopost) and serrated stainless steel posts (Parapost). Ten posts of each type were tested for rigidity in a three-point bend test. Ten posts of each type were cemented with resin cement into the roots of endodontically treated, extracted teeth. The tensile force required to remove the posts was recorded. The Paraposts proved to be significantly more rigid under load (P < 0.001) and significantly more strongly retained in the tooth roots (P < 0.005). The Parapost appears to be a mechanically superior post for the restoration of root-filled teeth with narrow diameter root canals.

Carbon↗
PubMed1999

Factors influencing the diagnosis and management of teeth with pulpal and periradicular disease by general dental practitioners. Part 2.

OBJECTIVE: To identify techniques commonly used in the management of periradicular disease by general dental practitioners and to ascertain views on continuing professional education in endodontics. DESIGN: Data was collected via a postal questionnaire distributed to 617 general dental practitioners in Scotland (33% of practitioners registered with the Dental Practice Board). RESULTS: 417 (69%) questionnaires were completed and returned. Only 24.9% of respondents used rubber dam routinely. The majority of respondents used hand instruments for preparation with either sodium hypochlorite or local anaesthetic being used most frequently for irrigation. The mean time for treatment of a single rooted tooth was 71 minutes. The demand for continuing education courses was high with 340 and 197 respondents requesting endodontic and rubber dam courses, respectively. CONCLUSIONS: Traditional methods for preparing the root canal using hand instruments were favoured by most dentists. The major disincentive to the use of rotary instruments and new techniques for obturating with thermally softened gutta-percha was expense. The importance of rubber dam isolation requires reiteration and more continuing education courses are required to update clinical skills.

Dental Pulp Diseases↗
PubMed1982

Holographic measurement of incisor extrusion.

A technique based on pulsed laser hologram interferometry was used to study the dynamics of incisor extrusion. Maxillary central incisors of four subjects were loaded with forces acting along the long axis of the tooth, and the resulting motions were measured noninvasively in three dimensions. The incisor translations and rotations were used to determine centers of rotation. The experimentally determined centers of rotation are shown to depend on tooth root geometry and are found to lie at a vertical level coincident with the centroid of the root.

Adult↗
PubMed2000

Development of multi-species consortia biofilms of oral bacteria as an enamel and root caries model system.

The aim was to establish defined-species consortium plaque biofilms to investigate enamel and root caries in an artificial mouth. Strains of the putative enamel and root caries pathogens, Streptococcus mutans, Strep. sobrinus, Actinomyces naeslundii and Lactobacillus rhamnosus, were screened in batch culture for potential cariogenic properties: a low terminal pH, ability to aggregate, and catabolic diversity. The strains selected were grown as monoculture biofilms and as consortium plaque biofilms in a multiplaque artificial mouth. The biofilms were supplied with a constant flow of a simulated oral fluid and were given periodic sucrose (and in some instances glucose) to simulate meals. All the bacteria except L. rhamnosus formed large, monospecies biofilms with resting pH in the range 5.3-5.8. The consortia biofilms were larger and had a resting pH of 4.9-5.3. The consortia biofilms supplied with 8-hourly carbohydrate comprised mainly 'mutans' streptococci (58, SD 5.5%) and L. rhamnosus (42, SD 5.7%). A. naeslundii characteristically was absent or present in a low percentage (up to 4% colony-forming units). All biofilms demineralized polished bovine enamel and dentine blocks, as assessed by microradiography and enamel-surface microhardness measurement. The consortia also demineralized intact enamel and tooth roots; they were more cariogenic to enamel than any of the monoculture biofilms, as measured by enamel-surface softening, but variation in lesion depth was proportional to biofilm wet weight irrespective of acidogen composition (r = 0.93, p < 0.05). Enamel lesions had a well-mineralized intact surface and a zone of subsurface demineralization, typical of early natural lesions. Dentine and root lesions showed extensive demineralization but lacked a pronounced surface mineralized zone. Substitution of glucose for sucrose had no effect on the cariogenicity of the consortium to bovine enamel or human roots and had no major effect on the plaque composition. Continuously supplied fluoride (19 parts/10(6)) resulted in a substantially reduced enamel surface softening and subsurface demineralization of intact roots. It was concluded that consortia biofilms of selected caries pathogens generate realistic caries lesions in all tooth hard tissues under controlled growth conditions in the artificial mouth. This in vitro caries experimental model may prove useful for the study of interrelations between the plaque biofilm, tooth tissues and the oral environment, and for the development of procedures to modify the course of caries development.

Actinomyces↗
PubMed2003

Sympathectomy causes increased root resorption after orthodontic tooth movement in rats: immunohistochemical study.

Accumulating evidence suggests that the sympathetic nervous system modulates inflammatory responses and bone remodeling. We have studied the effects of sympathectomy and orthodontic tooth movement (OTM) on root resorption, immunocompetent cell recruitment, neuropeptide, neurokinin-1 receptor (NK1-R), and interleukin 6 (IL-6) expression. Experimental rats (n=8) had the right superior cervical ganglion surgically removed, whereas control rats (n=6) underwent sham surgery. Three days later, all rats had the right maxillary first molar moved mesially by an orthodontic appliance. The rats were perfused 13 days later, and the right maxillae were processed for immunohistochemistry by using primary antibodies directed against ED1 antigen, CD43, substance P (SP), NK1-R, neuropeptide Y (NPY), and IL-6. Following OTM, sympathectomized (SCGx) rats had significantly more root resorption (P<0.01) and SP-immunoreactive (IR) fibers (P=0.01) in the compressed periodontal ligament (PDL) compared with control rats. There was a significant decrease in recruitment of CD43+ cells in the pulp after OTM in SCGx rats compared with control rats (P=0.02). An upregulation of NK1-R immunoreactivity was observed surrounding the hyalinized tissue, and an increase in the number of NK1-R IR cells and density of SP-IR fibers was present in first molar pulp of all rats. NPY-IR fibers were absent in the compressed PDL of SCGx and control rats. Thus, OTM induces remodeling not only around the periodontal tissues, but also in the dental pulp. The sympathetic nerves have an inhibitory effect on hard tissue resorption and a stimulatory effect on CD43+ cell recruitment after OTM.

Animals↗
PubMed2001

Cervicofacial subcutaneous emphysema after lower root canal therapy.

Subcutaneous emphysema can occur when high-speed, air-cooled, rotary cutting instruments are used near open wounds and introduce air into subcutaneous or facial spaces of the face and neck. The case reported here describes an episode of cervicofacial subcutaneous emphysema after lower tooth root canal therapy.

Adult↗
PubMed1979

The orthodontic center of rotation of the maxillary central incisor.

The cephalometric records of sixty-four Class II, Division 1 cases treated exclusively with removable orthodontic appliances have been used in a study of the manner in which maxillary central incisors tilt. The center of rotation was most frequently located in the middle third of the incisor root. The longer the time interval between the pre- and posttreatment cephalograms, the more apical was the rotation axis likely to be, an effect ascribed to growth changes in the maxilla. If the effects of growth are taken into account, it seems that the maxillary central incisor seldom, if ever, tilts about the apical third of its root when force levels customarily recommended for tipping movements are employed. The results suggest that the instantaneous and orthodontic centers of rotation are one and the same and support the view that the manner in which incisor teeth move in response to a single applied force depends principally on the physical properties of the tooth root, supporting bone, and periodontal membrane. An unexplained correlation was found between the rate of incisor movement measured at the cervical margin of the tooth and the level of the rotation center.

Adolescent↗
PubMed1992

Effect of precurving endosonic files on the amount of debris and smear layer remaining in curved root canals.

Endosonic files are prone to constraint; this reduces their efficiency, particularly in the apical third and in curved root canals. Precurving the file may reduce constraint, thereby improving the file's ability to debride. This investigation was undertaken to compare both straight and precurved endosonic files as to debris and smear layer removal. Thirty-six curved root canals were randomly allocated into six groups. Each group was prepared using a step-down technique, then instrumented with either a straight or precurved endosonic file of size 15, 20, or 25. The tooth roots were split and examined under the scanning electron microscope. Blind examinations were made for debris and smear layer removal and evaluation scores were analyzed using a log linear approach. The root canals instrumented with the precurved files had a significantly lower debris score than those prepared with straight files. Precurving did not affect smear layer removal. In conclusion, precurving of files decreased the amount of debris but did not affect smear layer removal.

Dental Cavity Preparation↗
PubMedDate not supplied

Long-term results of bovine mandibular fractures involving the molar teeth.

OBJECTIVE: To evaluate postoperative complications and long-term outcome of simple mandibular fractures involving the molar teeth in cattle. ANIMAL POPULATION: Seventeen cattle with mandibular fractures involving the molar teeth with disruption of the occlusal surface. METHODS: Treatment consisted of application of AO/ASIF-Pinless External Fixators (Synthes, Paoli, PA) in 14 cows, interdental wire stabilization in 1 cow, and conservative treatment in 2 cows. Long-term outcome was determined by telephone contact with the owners, and whenever possible, cows were reevaluated by physical, intraoral, and radiographic examination of the fracture site. RESULTS: Loosening of the fixation device (4 cattle) and bone sequestration (11 cattle) were the most commonly encountered complications. Oral incontinence during rumination was a minor complication in 1 cow. The mean (+/- SD) time the cattle were in production was 26 (+/- 14) months, with 10 cows still alive at follow-up examination; 9 cows were reevaluated. On intraoral examination there was a step in the occlusal surface at the level of the healed fracture site in 3 cows, wave and shear mouth formation in 3 cows, and enamel point formation in 1 cow. Radiographically, all the reevaluated fractures had healed, and there were no signs of tooth root infection. CONCLUSIONS: Complications during healing were bone sequestration and loosening of the fixator. None of the cows was removed from production because of fracture-associated complications, but decreased milk yield occurred in 2 cows. Tooth abnormalities developed in 6 cows, but function of the mandible was not altered. CLINICAL RELEVANCE: Mandible fractures involving the molar teeth carry a good prognosis for return to normal function. Radiographic follow-up is necessary to detect bone sequestration.

Animals↗
PubMed1996

A new challenge--root caries in mature people.

The future will bring many more root surface carious lesions in mature adults. Although traditional materials and procedures are acceptable for some patients, most are served best by use of cariostatic resin-modified glass ionomer materials, followed by additional fluoride augmentation for optimum tooth root surface caries prevention.

Adult↗
PubMed1997

Custom-made root analogue titanium implants placed into extraction sockets. An experimental study in monkeys.

The aim of this investigation was to evaluate clinically and histologically a new custom-made, root analogue titanium implant placed into extraction sockets in monkeys (Macaca fascicularis). Three adult monkeys were used in this investigation. After raising full thickness flaps on the buccal and lingual side, the upper central and lateral incisors were extracted. Each tooth root was machine copied to 1 titanium analogue using a new CAD/CAM-system. The implants were installed in the respective extraction sockets and the flaps sutured back. After 6 months of healing biopsies were taken and processed according to the cutting-grinding technique. The percentage of mineralized bone-to-implant contact was measured as a fraction of the rough implant surface using computer-assisted analysis. The main clinical problem that occurred during implant placement was the fracture of the buccal alveolar wall. The histometric evaluation showed a mean mineralized bone-to-implant contact of 41.2 +/- 20.6%. In this investigation it could be shown that implants fabricated by laser copying will osseointegrate. The presented data encourage the performance of clinical and experimental trials evaluating the new system utilizing improved second generation CAD/CAM equipment. Such studies are currently underway.

Animals↗
PubMed2006

Establishment of immortalized dental follicle cells for generating periodontal ligament in vivo.

The dental follicle is a mesenchymal tissue that surrounds the developing tooth germ. During tooth root formation, periodontal components, viz., cementum, periodontal ligament (PDL), and alveolar bone, are created by dental follicle progenitors. Here, we report the presence of PDL progenitors in mouse dental follicle (MDF) cells. MDF cells were obtained from mouse incisor tooth germs and immortalized by the expression of a mutant human papilloma virus type 16 E6 gene lacking the PDZ-domain-binding motif. MDF cells expressing the mutant E6 gene (MDF( E6-EGFP ) cells) had an extended life span, beyond 150 population doublings (PD). In contrast, normal MDF cells failed to proliferate beyond 10 PD. MDF( E6-EGFP ) cells expressed tendon/ligament phenotype-related genes such as Scleraxis (Scx), growth and differentiation factor-5, EphA4, Six-1, and type I collagen. In addition, the expression of periostin was observed. To elucidate the differentiation capacity of MDF( E6-EGFP ) cells in vivo, the cells were transplanted into severe combined immunodeficiency mice. At 4 weeks, MDF( E6-EGFP ) cell transplants had the capacity to generate a PDL-like tissue that expressed periostin, Scx, and type XII collagen and the fibrillar assembly of type I collagen. Our findings suggest that MDF( E6-EGFP ) cells can act as PDL progenitors, and that these cells may be a useful research tool for studying PDL formation and for developing regeneration therapies.

Alkaline Phosphatase↗