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At least 577 records · Page 32Linked to original sources
PubMedDate not supplied

Healing of mandibular body osteotomies after plate and intramedullary pin fixation.

Osteotomies were created in the left body of the mandible of nine dogs and immediately stabilized with either a six hole dynamic compression bone plate or an intramedullary pin. Cortical bone healing and vascular supply were evaluated at weeks 2, 5, and 10 by microradiography, microangiography, and correlated histology of selected mandibular slices. Perforating arterioles from the buccal mucosa maintained vascular supply to rostral mandibular segments. The mandibular body rostral to the osteotomy site and caudal to the canine tooth suffered an interruption of vascular supply that was replaced by a temporary extraosseous supply during healing of the osteotomy. Intramedullary pin placement resulted in destruction of rostral teeth. There was an inflammatory response around the rostral portion of all intramedullary pins. Osteotomy sites involving tooth roots resulted in no disruption of the normal vascular or neural structures of the tooth pulp.

Animals↗
PubMed1994

Effect of root canal status on periodontal healing after surgical injury in dogs.

This study was carried out to observe if the status of the root canal might influence the healing process of surgically prepared experimental periodontal lesions. Forty tooth roots from four dogs were divided into four different groups: a) root canals with vital pulps, b) root canals open to the oral environment, c) root canals infected and filled with zinc oxide eugenol cement, and d) root canals infected and filled with calcium hydroxide. By means of a surgical intervention, a cavity was prepared in the medium portion of the roots. Six months later, the specimens were removed and prepared for histological analysis. The results, which were submitted to statistical analysis, showed that the status of the root canals influenced the healing process of the experimental periodontal lesions. In the groups where the root canals were filled, calcium hydroxide gave the best results. In the group with root canals left open to the oral environment, resorption of the dentin of the experimental cavities, was the most obvious observation. However, it did not prevent the repair process, only slowed it down.

Analysis of Variance↗
PubMed2004

Effect of enamel matrix derivative on collagen guided tissue regeneration-based root coverage procedure.

BACKGROUND: Enamel matrix derivative (EMD) has been shown to promote periodontal wound healing and/or regeneration when applied to tooth root surfaces in soft tissue dehiscence models. In addition, guided tissue regeneration (GTR)-based root coverage using collagen membrane (GTRC) has shown promising results. However, limited information is available regarding how EMD may influence GTRC outcome. METHODS: Twenty-six patients with Miller's Class I or II gingival recession defects of 2.5 mm were recruited for the study. Subjects were randomly assigned to receive either EMD + collagen (EMDC; test group) or collagen membrane (GTRC; control group). Clinical parameters, including plaque index (PI), gingival index (GI), relative clinical attachment levels (RCAL) to the stent, recession depth (RD), recession width (RW), probing depth (PD), gingival tissue thickness (GTT), and width of keratinized gingiva (KG) were assessed at baseline, and 3 and 6 months after surgery. A repeated measure of analysis of variance (ANOVA) was used to determine differences between treatment groups and time effect. RESULTS: Both treatments (GTRC and EMDC) resulted in a statistically significant decrease in RD and RW between baseline and 6 months (P <0.05). However, no difference was noted between treatment groups. The percent of root coverage after 6 months was 75% for GTRC and 63% for EMDC. Complete 100% root coverage was achieved in five patients in the GTRC group, compared to only one patient in the EMDC group. There was a statistically significant gain (P <0.05) in the clinical attachment level (CAL) between baseline and 6 months in both groups, as reflected on the RCAL data. No other significant differences were noted on other clinical parameters (PD, GTT, KG, GI, and PI). CONCLUSIONS: GTR-based root coverage utilizing collagen membrane, with or without enamel matrix derivative, can be successfully used in obtaining gingival recession coverage. The application of EMD during GTRC procedures did not add additional benefit to the final clinical outcome.

Absorbable Implants↗
PubMed2003

Orbital penetration associated with tooth extraction.

Three cats and 2 dogs were evaluated for ophthalmologic complications associated with tooth extraction procedures. Orbital penetration leading to ocular and, in one case, brain trauma was secondary to iatrogenic injury from a dental elevator. Outcomes included enucleation of the affected eye in 3 cases, and death from brain abscessation in 1 case. Early treatment or, preferably, referral to a veterinary ophthalmology specialist may prevent such outcomes. Awareness of the anatomical proximity of caudal maxillary tooth roots and the orbit, appropriate interpretation of diagnostic intraoral dental radiographs, and technical proficiency in tooth extraction techniques will minimize these complications in veterinary dental practice.

Animals↗
PubMedDate not supplied

[Experiments to determine the time dependent material properties of the periodontal ligament].

The periodontal ligament is a tissue that attaches the tooth (root) to its alveolar socket, and thus plays an important role in the regulation of tooth movements. Detailed knowledge of the material properties of the periodontal ligament is therefore essential to an understanding of tooth reaction to forces applied during orthodontic treatment. A knowledge of material parameters can also be used in simulations of long-term tooth movements with the aim of improving orthodontic treatment. To this end, this study investigated time-dependent material properties, namely the hysteresis behaviour of the periodontal ligament under constant-velocity loading, the influence of loading velocity on the hysteresis, and its failure under constant loading. Specimens obtained from pigs were used for testing purposes, and the experiments were conducted in a special test setup using a material testing device. The material behaviour of the periodontal ligament was shown to be viscoelastic, and the elastic parameters of material behaviour were also determined. Under constant-velocity loading, material behaviour showed a nonlinear course of the stress-strain curve, also known as hysteresis. When loading was repeated several times, the maximum stress of the hysteresis decreased with each cycle. Determination of the deflection of the specimen at different velocities showed maximum stress to be dependent on the loading rate. The measured stress-strain curves were approximated by bilinear behaviour, permitting the use of finite element calculations. Also investigated was the failure behaviour of the periodontal ligament, which revealed tissue rupture to be inconstant.

Animals↗
PubMed1996

[Characterization of rat periodontal ligament cells in culture].

It has been reported that periodontal ligament cells (PDLC) show osteoblastic phenotypes in culture. In most previous studies, PDLC have been obtained from the tooth root surface, however, a new method in which PDLC are obtained from the coagulum after tooth extraction has been proposed recently. To compare PDLC from tooth surface with these from coagulum, PDLC from both sources were cultured and examined. PDLC from both sources responded to PTH or PGE2 increasing cAMP and showed high alkaline phosphatase (ALP) activity. Some PDLC cultures produced mineralized tissues and these mineralizing cultures showed high ALP activity with high gene expression level of type I collagen, bone sialoprotein, and osteopontin in comparison with non-mineralizing cultures. PDLC from both sources expressed various osteoblastic or cementoblastic phenotypes and seemed to contain heterogenous mesenchymal cell population with various differentiation potentials. However, the frequency of cellular transmigration, rate of mineralized tissue formation, increased level of cAMP that responded to PTH or PGE2, and osteopontin expression pattern were different between PDLC from both sources. These differences indicate that PDLC cultures from coagulum contain more immature cells than PDLC from tooth surface.

Animals↗
PubMed1989

[Analysis of movement in partial prostheses and abutment teeth with differences in retainer].

When designing a prosthesis in a clinical setting that takes into consideration the protection of the abutment teeth and alveolar ridge, it remains difficult to carry out a method of connecting the abutment tooth and prosthesis based on objective grounds. This is because there are still many matters that remain unclear about dynamics of the stomatognathic system, including the prosthesis, when attached in the oral cavity. The author created the following three prostheses on a stimulation model of a tooth bone saddle that included an artificial mucous membrane and periodontal membrane: (1) A fixed bridge, (2) A telescopic denture (Konuskronen Telescope), (3) An Akers clasp denture. Following this, flat-controlled random noise was applied to each denture to create a dynamic load that exhibits a state closer to a clinical situation. Modal analysis was carried out with a laser doppler vibrometer and observations were made of the prosthesis and the abutment tooth apex to obtain visual clarification of dynamics, The following results were obtained. 1. As far modal resonant frequency, in mode #1, the bridge measured at 483 Hz and 561 Hz, the Telescope at 452 Hz and 600 Hz and the clasp at 581 Hz and 596 Hz. In mode #2 the bridge measured at 1,355 Hz and 1,370 Hz, the Telescope at 1,343 and 1,040 Hz and the clasp at 1,114 Hz and 1,079 Hz. In mode #3, only the bridge was detected and the recorded values 1,906 Hz and 2,026 Hz. 2. The influence on the modal resonant frequency due to the difference in abutment devices was limited. 3. Observation of animation indicated that the tendency for lateral movement of the abutment teeth increased going from the bridge to the Telescope to the clasp. 4. Displacement of the abutment tooth root apex decreased in reverse proportion to the strength of the connection between the abutment tooth and the abutment device.

Dental Abutments↗
PubMed1979

Bone maintenance: implant versus transplant.

Bone maintenance based on various attachment mechanisms is the key to tooth-root replacement safety and efficacy. The dental implant has broad applicability based on design, but demonstrates progressive peri-implant bone loss. The allogeneic tooth transplant, significantly less applicable because of size, is antigenic and rejected by bone-replacement root resorption. Since the predictability and survival times of these implant and transplant modalities are similar and there is less residual bone loss with the transplant, it is suggested that for clinical situations such as the fresh extraction socket, where there is room, the allotransplant, rather than implant, is the root-replacement of choice.

Alveolar Process↗
PubMed1994

A possible explanation for the response characteristics of multi-tooth periodontal ligament mechanoreceptors in the cat.

During the course of a study on the morphology of periodontal ligament mechanoreceptors it was observed that a direct relation, without intervening bone, existed between the mandibular canine and first premolar tooth roots in the cat. An area, representing a window in the alveolar septal bone, extended 2-3 mm from the apex towards the tooth crown. Ruffini nerve terminals were observed amongst the collagen bundles in the ligament between the roots of the two teeth. Light and electron microscopy were used to identify the receptors. It is proposed that a periodontal ligament mechanoreceptor can respond to forces applied to adjacent teeth; movement of both teeth need not occur. This may explain the observation made in the past that single periodontal ligament mechanoreceptors respond to forces applied to more than one tooth.

Alveolar Process↗
PubMed1999

Effect of recombinant human platelet-derived growth factor-BB and bone morphogenetic protein-2 application to demineralized dentin on early periodontal ligament cell response.

The purpose of this study is to investigate the early responses of human periodontal ligament cells attached to recombinant human platelet-derived growth factor-BB and bone morphogenetic protein-2 applied EDTA-demineralized dentin. One hundred and seventy-four root-planed flat dentin blocks were prepared from the mid-third of periodontally diseased human tooth roots. After demineralization with 24% EDTA (pH 7.02) 120 dentin blocks were treated with 0.5 and 1 microgram/ml rhPDGF-BB, 1 and 3 micrograms/ml rhBMP-2 and only MEM as control (24/group). Human periodontal ligament cells (HPLC) were seeded on these dentin surfaces and incubated. The alkaline phosphatase (ALP) activity and protein concentration of the attached cell were assessed at d 2, 4 and 7. Fifty-four dentin blocks were seeded with HPLC after application of 1 microgram/ml rhPDGF-BB, 3 micrograms/ml rhBMP-2 and MEM (18/group) and then incubated. At d 2, 4 and 7, the attached cells were stained and counted under light microscope. The results showed a significant increase of protein concentration and cell number in PDGF-BB treated groups than control (p < 0.05, p < 0.01) but not the ALP activity, and a significant increase of ALP activity was observed in BMP-2 treated groups than control (p < 0.05) but protein concentration and cell number remained almost the same over time. Thus, rhPDGF-BB and rhBMP-2 application to EDTA demineralized dentin surfaces promote the early human periodontal ligament cell responses by increasing cell proliferation and differentiation, respectively, which would ultimately enhance periodontal regeneration.

Adolescent↗
PubMed1982

The distribution of mechanoreceptors in the periodontal ligament of the mandibular canine tooth of the cat.

1. Periodontal mechanoreceptor activity has been recorded from fibres in the inferior alveolar nerve. 2. A method has been developed for punctate and electrical stimulation of the periodontal ligament mechanoreceptors through a thin layer of bone overlying the labial aspect of the left mandibular canine tooth root. 3. The distribution of periodontal mechanoreceptors in the labial aspect of the left mandibular canine tooth has been described. 4. All receptors located responded maximally when that part of the ligament in which they lay was in tension. 5. It is suggested that there may be only one type of mechanoreceptor and that the rate of adaptation is dependent on the location of the receptor within the periodontal tissues.

Animals↗
PubMedDate not supplied

Effect of core bonding on fatigue failure of compromised teeth.

PURPOSE: This study determined the effect of bonding a composite core on the number of load cycles to cement failure for teeth restored with complete crowns. MATERIALS AND METHODS: Ten extracted human maxillary central incisors were divided into two groups of five each. The tooth roots were at least 11 mm long, allowing an 8-mm post. Under copious irrigation, each tooth was cut to a flat plane 1 mm coronal to the buccal cementoenamel junction, perpendicular to the long axis of the tooth. The canal space was prepared to a final diameter of 1.25 mm, 8 mm deep. Each tooth was rebuilt with a 050 Parapost and Corestore. Final preparation height was 7 mm, including a 1-mm ferrule. For group 1, the core was bonded to the dentin using autocured Scotchbond Multipurpose Plus. For group 2, the core was not bonded. Following crown cementation, all teeth were subjected to a fatigue load of 4 kg at a rate of 280 cycles per minute. RESULTS: One tooth with a bonded core failed at 19,880 cycles, and the other four in this group did not fail after 100,000 cycles. All of the teeth without a bonded core failed at a cycle count of less than 100. The Mann-Whitney nonparametric test showed a significant difference between the two groups (P < .01). CONCLUSION: Bonding of a composite core to dentin prior to crown cementation provided a significantly stronger crown retention under fatigue loading.

Composite Resins↗
PubMed2006

Labiomandibular paresthesia caused by endodontic treatment: an anatomic and clinical study.

Labiomandibular paresthesia after root canal treatment is an accident that is still too frequent despite the development of new endodontic techniques. The aim of this anatomical and clinical study is to advance the understanding of how accidents occur so as to avoid them. This anatomical study made it possible to determine the variability of proximity of the apex of the tooth root to the mandibular bundle, as well as the relationship between the nerve and its satellite artery, and to understand how endodontic filling material spreads into the cancellous bone. The clinical study, which included examination with conventional radiology as well as with imaging techniques, enabled us to identify the exact location of the filling material in relation to the mandibular bundle and to correlate this to the occurrence of clinical symptoms and their diverse manifestations.

Cranial Nerve Injuries↗
PubMed1987

The effect of an antibiotic/corticosteroid paste on inflammatory root resorption in vivo.

Progressive external inflammatory root resorption, a result of persistent inflammation within the periodontal membrane, will cause eventual destruction of the tooth root if the inflammation is not eradicated. This study examined the effects of an antibiotic/corticosteroid paste on experimental inflammatory resorption induced in monkeys in vivo. Histologic evaluation of results with the use of a morphometric technique revealed that the paste eliminated inflammatory root resorption and had no damaging effects upon the periodontal membrane. It was concluded that this antibiotic/corticosteroid combination is an effective medication for use in the treatment of progressive root resorption in traumatically injured teeth.

Animals↗
PubMed1984

Endodontic treatment of a cementoblastoma.

The benign cementoblastoma (true cementoma, osteoblastoma, giant osteoid osteoma) appears to be a true neoplasm of functional cementoblasts which proliferate at the apex of teeth to form an expansile tumor. It remains intimately attached to the tooth roots and occasionally involves the root canals themselves. Although the pulpal tissue remains vital, treatment has historically consisted of extraction of the involved tooth along with extirpation of the tumor. This mode of therapy for the benign cementoblastoma should not be confused with the entity called periapical cemental dysplasia (that is cementoma, periapical osteofibroma or osteofibrosis, cementifying fibroma, localized fibro-osteoma, and periapical fibrous dysplasia). In this latter lesion the treatment consists of simply recognizing the condition and establishing a schedule for periodic evaluation of the patient. In the case presented here enucleation of the cementoblastoma and endodontic therapy were selected as treatment modalities, despite the presence of buccal and lingual expansion of the cortical plates. There has been no recurrence of this growth during the 4-year follow-up period.

Adult↗
PubMed2005

[Association between Bacteroides forsythus in the infected root canals and clinical symptoms of chronic apical periodontitis].

OBJECTIVE: To investigate the distribution of Bacteroides forsythus in root canals with chronic apical periodontitis and to determine its associations with clinical symptoms. METHODS: Thirty-eight tooth root canals from 31 subjects were studied with a 16S rDNA-directed polymerase chain reaction (PCR). These teeth were classified into symptomatic and asymptomatic groups according to the clinical symptoms and signs, including spontaneous pain, percussion pain, sinus tract and swelling, respectively. RESULTS: Ten of the 38 root canal samples were positive for B. forsythus. The prevalence of B. forsythus was 26.3% for 38 root canals, 45.5% for spontaneous pain group, 39.1% for percussion pain group, 29.4% for sinus tract group, 42.9% for swelling group, respectively. Significant positive associations were observed between B. forsythus in infected root canals and the spontaneous pain, percussion pain, and swelling of apical periodontitis, respectively (OR=infinity, 9, 12; P<0.05). There was no significant association between B. forsythus and sinus tract of apical periodontitis (OR=1.33). CONCLUSION: B. forsythus colonized in the infected root canals. It is the putative pathogen of apical periodontitis.

Adolescent↗
PubMed1994

In vitro studies on laser scaling of subgingival calculus with an erbium:YAG laser.

The effectiveness of a newly-developed Er:YAG laser with a fiber delivery system to remove subgingival calculus was examined in vitro. Fifty-three (53) periodontally-involved human extracted teeth with a band of subgingival calculus were used. Two experiments were conducted: in experiment 1, laser scaling was performed with water irrigation on a straight line and on a broad area, against the subgingival calculus at the energy levels of 10 to 120 mJ/pulse (3.5 to 42.4 J/cm2/pulse) and the pulse repetition rate of 10 pps. The morphological changes of the laser-scaled site were observed by SEM, and the efficiency of laser scaling was determined. In experiment 2, laser scaling was performed with and without water irrigation at 30 mJ/pulse and 10 pps. The morphological changes, the efficiencies, and temperature changes with and without water irrigation were compared. The pulsed Er:YAG laser used with water irrigation was able to remove the subgingival calculus from the tooth root effectively at the energy level of about 30 mJ/pulse (energy density: 10.6 J/cm2/pulse) and 10 pps, under in vitro conditions. Ablation of the tooth substance on laser scaling was generally observed within the cementum. There was little increase in temperature on the root surface during laser scaling. This study suggests the potential for the clinical application of the Er:YAG laser in subgingival scaling.

Analysis of Variance↗