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PubMed2006

Chemical factors.

pH value, calcium, and phosphate and to a lesser extent fluoride content of a drink or foodstuff are important factors explaining erosive attack. They determine the degree of saturation with respect to tooth minerals, which is the driving force for dissolution. Solutions oversaturated with respect to dental hard tissue will not dissolve it. Addition of calcium (and phosphate) salts to erosive drinks showed protection of surface softening. Today, several Ca-enriched soft drinks are on the market or products with naturally high content in Ca and P are available (such as yoghurt), which do not soften the dental hard tissue. The greater the buffering capacity of the drink or food, the longer it will take for the saliva to neutralize the acid. The buffer capacity of a solution has a distinct effect on the erosive attack when the solution remains adjacent to the tooth surface and is not replaced by saliva. A higher buffer capacity of a drink or foodstuff will enhance the processes of dissolution because more ions from the tooth mineral are needed to render the acid inactive for further demineralization. Further, the amount of drink in the mouth in relation to the amount of saliva present will modify the process of dissolution. There is no clear-cut critical pH for erosion as there is for caries. Even at a low pH, it is possible that other factors are strong enough to prevent erosion.

Beverages↗
PubMed2003

Periodontal regeneration in humans using recombinant human platelet-derived growth factor-BB (rhPDGF-BB) and allogenic bone.

BACKGROUND: Purified recombinant human platelet-derived growth factor BB (rhPDGF-BB) is a potent wound healing growth factor and stimulator of the proliferation and recruitment of both periodontal ligament (PDL) and bone cells. The hypothesis tested in this study was that application of rhPDGF-BB incorporated in bone allograft would induce regeneration of a complete new attachment apparatus, including bone, periodontal ligament, and cementum in human interproximal intrabony defects and molar Class II furcation lesions. METHODS: Nine adult patients (15 sites) with advanced periodontitis exhibiting at least one tooth requiring extraction due to an extensive interproximal intrabony and/or molar Class II furcation defect were entered into the study. Eleven defects were randomly selected to receive rhPDGF-BB. Following full-thickness flap reflection and initial debridement, the tooth roots were notched at the apical extent of the calculus, the osseous defects were thoroughly debrided, and the tooth root(s) were planed/prepared. The osseous defects were then filled with demineralized freeze-dried bone allograft (DFDBA) saturated with one of three concentrations of rhPDGF-BB (0.5 mg/ml, 1.0 mg/ml, or 5.0 mg/ml). Concurrently, four interproximal defects were treated with a well accepted commercially available graft (anorganic bovine bone in collagen, ABB-C) and a bilayer collagen membrane. Radiographs, clinical probing depths, and attachment levels were obtained preoperatively (at baseline) and 9 months later. At 9 months postoperatively, the study tooth and surrounding tissues were removed en bloc. Clinical and radiographic data were analyzed for change from baseline by defect type and PDGF concentration. The histologic specimens were analyzed for the presence of regeneration of a complete new attachment apparatus coronal to the reference notch. RESULTS: The post-surgical wound rapidly healed and was characterized by firm, pink gingivae within 7 to 10 days of surgery. There were no unfavorable tissue reactions or other safety concerns associated with the treatments throughout the course of the study. In rhPDGF/allograft sites, the vertical probing depth (vPD) reduction for interproximal defects was 6.42 +/- 1.69 mm (mean +/- SD) and clinical attachment level (CAL) gain was 6.17 +/- 1.94 mm (both P < 0.01). Radiographic fill was 2.14 +/- 0.85 mm. Sites filled with ABB-C had a PD reduction and CAL gain of 5.75 +/- 0.5 and 5.25 +/- 1.71, respectively. Furcation defects treated with rhPDGF/allograft exhibited a mean horizontal and vertical PD reduction of 3.40 +/- 0.55 mm (P < 0.001) and 4.00 +/- 1.58 mm (P < 0.005), respectively. The CAL gain for furcation defects was 3.2 +/- 2.17 mm (P < 0.030). Histologic evaluation revealed regeneration of a complete periodontal attachment apparatus, including new cementum, PDL, and bone coronal to the root notch in four of the six interproximal defects and all evaluable (four of four) furcation defects treated with PDGF. Two of the four interproximal intrabony defects treated with ABB-C and membrane exhibited regeneration. CONCLUSIONS: Use of purified rhPDGF-BB mixed with bone allograft results in robust periodontal regeneration in both Class II furcations and interproximal intrabony defects. This is the first report of periodontal regeneration demonstrated histologically in human Class II furcation defects.

Adult↗
PubMed2005

The treatment of deep dentine caries lesions.

UNLABELLED: This paper discusses the excavation of deep caries lesions, focusing on indirect pulp-capping and the stepwise excavation approach. The concept of a modified and less invasive stepwise excavation is presented, based on considerations of caries pathology. The aim of the first excavation is primarily to make a change within the cariogenic environment, and not to remove carious dentine close to the pulp because this risks an iatrogenic pulp exposure. Microbiological and clinical studies have shown that the number of bacteria decrease during stepwise excavation procedures, and that lesions clinically arrest. The active, soft-yellowish, demineralized dentine turns into a darker, harder and drier demineralized dentine, resembling a slowly progressing lesion, where the carious dentine is easier to remove at the final visit. The final excavation has two aims: (i) to verify that arrestation has taken place, ie a clinical control of the tooth reactions and (ii) to remove the slowly progressing but still slightly infected discoloured demineralized dentine, before carrying out the permanent and final restoration. CLINICAL RELEVANCE: Knowledge of guidelines for treatment of deep dentine caries may reduce the risk of pulpal exposure.

Dental Caries↗
PubMed1999

Clinical evaluation of the treatment of class II furcation involvements with bioabsorbable barriers alone or associated with demineralized freeze-dried bone allografts.

BACKGROUND: Class II furcation lesions are a challenging scenario for periodontal therapy and a serious threat for tooth prognosis. Guided tissue regeneration represents a viable treatment option, but some aspects remain to be clarified as to the efficacy of bone substitutes used in GTR procedures. The clinical efficacy of demineralized freeze-dried bone allografts (DFDBA) for regenerative procedures is presently under scrutiny. METHODS: This study evaluated the adjunctive clinical effects of DFDBA associated with a bioabsorbable (polylactic acid) barrier membrane in the regenerative treatment of human Class II furcation lesions as compared to the same type of barrier alone. Twelve patients with bilateral Class II furcation defects on lower first molars participated in the study. In each patient, one tooth was randomly assigned to treatment consisting of open surgical debridement followed by the placement of DFDBA (GTR+DFDBA, or test group) and a bioabsorbable barrier, while the contralateral side received the same flap surgery followed by use of the bioabsorbable membrane alone (GTR, or control group). The clinical efficacy of the 2 treatment modalities was evaluated at 6 and 12 months postoperatively. Measurements included vertical probing depth (VPD), horizontal probing depth (HPD), clinical attachment level (CAL), amount of gingival recession (GR), and change in class of clinically detectable furcation involvement (FC). RESULTS: Both treatments yielded significant improvements for all clinical parameters between baseline and 6 and 12 months (P<0.05). The comparison between test and control groups revealed significantly greater reduction in HPD (P=0.01) and higher values of GR (P=0.008) for the test group. The mean gain in HPD for test sites was 2.3 mm, while it amounted to 1.7 mm for controls. A significantly greater proportion of test sites could be classified postoperatively as Class I defects compared to controls (91% versus 50%, respectively). CONCLUSIONS: The results of this study indicate that significant improvements from baseline occurred in VPD, HPD, CAL, and clinically detectable furcation involvement after the treatment of Class II furcation lesions with a bioabsorbable membrane with or without the adjunctive use of DFDBA. In addition, the placement of DFDBA in the furcation defect under the bioabsorbable membrane resulted in a greater mean reduction of horizontal probing depth when compared to the regenerative therapy alone.

Absorbable Implants↗
PubMed1997

Bone regeneration around an osseointegrated implant. A simultaneous approach in a fenestrated defect: a case report.

The use of a barrier membrane, with or without osseous allograft, has been shown to establish regeneration of osseous tissue around dental implants. Following three episodes of persistent symptomatic failed apicoectomy and subsequent tooth extraction, an osseointegrated implant was placed in a wide fenestrated defect. Demineralized freeze-dried bone allograft was covered by an occlusive expanded polytetrafluorethylene membrane. The reentry procedure revealed complete bone fill that followed the texture of the augmentation material beyond the previous buccal bony envelope.

Adult↗
PubMed2006

Effect of tumor therapeutic irradiation on the mechanical properties of teeth tissue.

Tumor irradiation of the head-neck area is accompanied by the development of a so-called radiation caries in the treated patients. In spite of conservative therapeutic measures, the process results in tooth destruction. The present study investigated the effects of irradiation on the demineralization and remineralization of the dental tissue. For this purpose, retained third molars were prepared and assigned either to a test group, which was exposed to fractional irradiation up to 60 Gy, or to a non-irradiated control group. Irradiated and non-irradiated teeth were then demineralized using acidic hydroxyl-cellulose gel; afterwards the teeth were remineralized using either Bifluorid12 or elmex gelee. The nanoindentation technique was used to measure the mechanical properties, hardness and elasticity, of the teeth in each of the conditions. The values were compared to the non-irradiated control group. Irradiation decreased dramatically the mechanical parameters of enamel and dentine. In nonirradiated teeth, demineralization had nearly the same effects of irradiation on the mechanical properties. In irradiated teeth, the effects of demineralization were negligible in comparison to non-irradiated teeth. Remineralization with Bifluorid12 or elmex gelee led to a partial improvement of the mechanical properties of the teeth. The enamel was more positively affected by remineralization than the dentine.

Elasticity↗
PubMed2002

Peroxide interactions with hard tissues: effects on surface hardness and surface/subsurface ultrastructural properties.

Laboratory studies were performed to assess the impact of peroxide bleaching on enamel surface and subsurface physical and ultrastructural properties. Human enamel blocks were prepared, polished, and measured for native color. Cyclic bleaching treatments were carried out with soaks in whole stimulated saliva interspersed with bleaching treatments using bulk bleaching gels from commercial bleaching systems including Opalescence (20% and 10% carbamide peroxide systems) and Crest Whitestrips, a hydrogen peroxide gel formula, at doses of 5.3% and 6.5% hydrogen peroxide. Treatments ranged from conditions of normal use (14 hours as recommended for Crest Whitestrips) to excessive bleaching (70 hours). Controls included nontreated as well as treatments with placebo (not containing peroxide) gels. Surface hardness and confocal laser scanning microscopy (CLSM) techniques were used to characterize the effects of bleaching on the physical properties and ultrastructure of the teeth. Tooth color measurements revealed dose-response bleaching in vitro with the increases in L* and decreases in b* normally expected with effective bleaching. Placebo control treatments did not bleach. Surface hardness measurements showed no decreases associated with tooth bleaching. CLSM measurements also showed no effects from tooth bleaches on the surface or subsurface prism architecture of enamel. This was opposed to significant changes seen with even moderate levels of demineralization associated with the caries process. These studies support: (1) the safety of Crest Whitestrips formulas for enamel surfaces and tooth subsurfaces; and (2) the generic safety of peroxide bleaching of hard tissues associated with conditions of both recommended use and overuse.

Acrylic Resins↗
PubMed1989

[Effects of Er:YAG laser irradiation on human extracted teeth].

The ablation effects of the Erbium:YAG laser (wave length: 2.94 microns) on the human extracted teeth were examined histopathologically. The enamel surface of the human extracted tooth was irradiated by the laser at 500 mJ, 1 pps or 3 pps: 3, 15, 30, 50 and 100 shots. After observation under a dissecting microscope, the teeth were placed in a demineralizing solution of 0.1 M lactate buffer with 6% hydroxyethyl cellulose (pH 4.5) in order to evaluate the acid resistance of the enamel adjacent to the ablated area. After 4 days, the degree of demineralization of the surrounding enamel was assessed by contact microradiography. The result showed that every irradiated tooth had a clear-cut defect, and almost all the teeth had acquired acid resistance at the enamel surrounding the ablated portion. The other experiment was carried out to estimate the effects of the Er:YAG laser through a contact probe. The enamel, dentin and cementum of the extracted teeth were irradiated at 39 mJ or 74 mJ, 10 pps; 10 shots. The teeth were observed under a dissecting microscope. The result clearly indicated that the Er:YAG laser guided by the contact probe could also produce a defect in the dental hard tissue. The above-mentioned findings suggested that the Er:YAG laser could pave the way for the cavity preparation with acid-resistant cavity margin.

Dose-Response Relationship, Radiation↗
PubMed1995

Orthodontic movement through a repaired buccal alveolar fracture: a case report.

Orthodontic treatment in adults often involved the extraction of a lower central incisor. The extraction of these teeth can be problematic. Some factors that can influence successful treatment include: difficult access for actual tooth removal; the existing contour and bulk of the alveolar ridge; the buccal tooth position; and the inclination of the tooth in the alveolus. A patient who had a lower central incisor removed experienced a buccal alveolar fracture because of thin buccal plate. Upon healing there was a buccal defect that prevented the later tooth movement that would have closed the extraction site. The area was grafted with a demineralized freeze dried bone allograft to provide a matrix for osteoinduction. Gore-Tex was used as the physical barrier. After 6 months, the extraction side was closed by passing the lateral incisor through the graft site. The result was good tooth alignment and slight horizontal bone loss in the defect area.

Adult↗
PubMed1984

The in vivo corrosion of Dispersalloy.

The in vivo corrosion of Dispersalloy amalgam restorations was characterized by scanning electron microscopy and energy dispersive X-ray analysis. It was observed that the corrosion of CuSn resulted in pitting on the restoration surface. Corrosion of Sn-rich grain boundaries led to intergranular separation of gamma 1 grains. The tin released through corrosion reacted with Ca, P, Cl and O forming various insoluble complexes on the external surface, at the tooth-amalgam interface, and within the interior of the restoration. The demineralization of the amalgam-adjacent margin has been attributed to corrosion.

Chemical Phenomena↗
PubMedDate not supplied

[Changes in the microhardness of the enamel and dentin in pulp inflammation].

Clinical and experimental studies of the dental enamel and dentin microhardness were carried out. A comparative analysis has made it possible to detect parallels in the changes of dental tissue microhardness in humans and dogs. The studies have revealed a focal pattern of demineralization, with the foci located mainly in the neck of the tooth and the pericervical portion of the root, indicating a considerable reduction of the functional resistance of pulpless teeth.

Adult↗
PubMed1989

In vitro interaction between gingival fibroblasts and various root surfaces.

The objective of the present in vitro study was to examine the effect of various root surface treatments on the initial attachment of gingival fibroblasts. Cultured fibroblasts were well spread and attached to demineralized dentin with citric acid, superficially curetted cementum, and root surface with periodontal ligament, while those on the planed dentin showed a poorly spread appearance. The first three root surfaces exhibited rough and irregular surface appearances with a well-developed filopodia and the latter root surface exhibited a smooth appearance, suggesting the texture of the root surface is closely associated with cell attachment. Interiorized collagen fibrils and numerous cytoplasmic vesicles were seen along the cell membrane of fibroblasts facing the root surfaces of the planed dentin, demineralized dentin, and superficially curetted cementum. Thus even the artificially exposed tooth surface with citric acid may be subjected to further alteration by fibroblasts.

Animals↗
PubMed2004

Effect of acid etching time and technique on interfacial characteristics of the adhesive-dentin bond using differential staining.

Dentin bonding using the total-etch method has been claimed to be technique-sensitive. The aim of this study is to examine the effect of acid-etch variations on the dentin demineralization and interfacial structure of the adhesive-dentin bond using a differential staining technique. Single Bond adhesive with 35% phosphoric acid gel was used. The occlusal one-third of the crown was removed from 60 extracted, unerupted human third molars. Smear layers were created by abrading the dentin with 600 grit SiC under water for 30 s. The prepared teeth were randomly assigned to four groups according to etching time (Group 1, 10 s; Group 2, 15 s; Group 3, 30 s; Group 4, 60 s). In each group, the etching gel was: (i) applied and spread to the dentin surface and left to stand undisturbed; (ii) applied and gently agitated during etching; (iii) applied without using dispensing tips for the syringe and left for the same period as above. After rinsing, the etched dentin was then treated with the adhesive per manufacturers' instructions. 3-5 micro m thin sections of the adhesive/dentin (a/d) interface were cut with a microtome and stained with Goldner's trichrome. Stained, thin sections from each prepared tooth were imaged with light microscopy. The depth and extent of dentin demineralization, and the a/d interdiffusion zone were clearly visible by this differential staining microtechnique. The thickness of the interdiffusion zone increased as a function of etching time. However, the etchant gel application methods have a significant influence on dentin demineralization. Although agitating acid gel facilitates the penetration and etching into dentin, it should not be recommended, especially for longer etching time. These results indicated that the etching technique has a large effect on the profile of both dentin demineralization and interfacial structure.

Acid Etching, Dental↗
PubMed1989

Attachment to and phagocytosis of mineral by alveolar bone osteoclasts.

The mechanisms by which the osteoclast attaches to and resorbs bone are not fully understood. Morphologic techniques have primarily been used to examine these mechanisms, but many studies have been based on decalcified material. In this study, the attachment of the osteoclast to alveolar bone and its relationship to the mineral component during the active resorption associated with tooth eruption in the rat was examined using transmission electron microscopy and techniques designed to minimize demineralization effects during processing. Large conglomerates of bone mineral were found within both the ruffled border and the vacuoles adjacent to this area. These deposits were clearly more extensive than the isolated mineral fragments described in other sites by previous investigators. Examination of demineralized sections showed that collagen was largely absent within the ruffled border, and not present within vacuoles. These observations suggest that phagocytosis of bone mineral may supplement its extracellular dissolution in situations associated with rapid bone turnover, such as tooth eruption. Two types of clear zone attachment to mineral were also observed, permitting further speculation on the mechanism by which osteoclasts attach to and move along the bone surface.

Animals↗
PubMed1984

The effect of citric acid on repair after delayed tooth replantation in dogs.

An experimental study of maxillary incisors in dogs was carried out to test the hypothesis that demineralization of denuded root surfaces by citric acid to expose collagen matrix fibrils might improve the rate of periodontal regeneration after replantation of traumatically avulsed and dried teeth, provided that the root surface is not traumatized during replantation or postoperatively. Experimental teeth (group 4) were allowed to dry in air for 45 min. A mid-portion of the root was then root-planed extensively, treated with citric acid for 3 min, rinsed with saline, and replanted. The apical region and a cervical collar were not instrumented, ensuring precise reseating and stability of the tooth during the postoperative period. Control teeth were either replanted immediately (group 1), bench-dried for 45 min and replanted (group 2), or bench-dried and the entire root surface root-planed and acid-treated before replantation (group 3). Histological examination of block specimens after 21 days of healing showed complete periodontal regeneration in group 1 and, by contrast, a high rate of ankylosis, inflammatory resorption, and surface resorption in group 2. Root planing and acid treatment of bench-dried teeth (group 3) did not improve the healing response, whereas the mid-root region of teeth in group 4 showed an absence of inflammatory resorption and less ankylosis than groups 2 and 3. These preliminary observations indicate that the frequency of adverse healing results after delayed replantation can be reduced by removing nonvital soft tissue remnants, demineralizing the root surface, and preventing mechanical trauma to the root surface in the postoperative period.

Animals↗
PubMed2001

[The experimental study of the delayed replantation after cryopreservation of mature tooth in dogs].

OBJECTIVE: To study the conditions of healing of mature tooth in dogs after long cryopreservation followed by replantation. METHODS: The tooth was extracted after filling the root canals and then preserved for one week and three months respectively by Schwartz's method of cryopreservation of periodontal membrane. The specimens were took out eight weeks after replantation. It was demineralized in a 5% solution of formic acid,and then sectioned perpendicular to the long axes of tooth at a thickness of 5microm. The tooth were sectioned in step-serial sections at 500 microm intervals. The sections were stained with hematoxylin-eosin and followed by evaluation according to Andreasen. RESULTS: The percentage of healing of periodontal membrane (PHPM) of the group of cryopreservation for one week was 64.53%. It was lower than the PHPM of the group of immediate replantation (85%), but the difference demonstrated no significance (P>0.05). The PHPM of the group of cryopreservation for three months was 50.3%. It was lower than the PHPM of the group of immediate replantation significantly (P<0.05). CONCLUSION: The human's periodontal membrane may be cryopreserved longly and heals after the replantation of tooth as the human's tissues of corneas, skin, islets, et al may be done. The alveolar cavities to be newly made affect the healing of periodontal membrane in some degree.

English Abstract↗
PubMed1977

Identification of four extracellular-matrix enamel proteins during embryonic-rabbit tooth-organ development.

1. Investigations were designed to identify the proteins which characterize the ameloblast phenotype, and to determine to what extent these extracellular-matrix proteins were degraded as a function of enamel matrix mineralization and maturation. 2. The identification of enamel proteins was based on comparisons between the electrophoretic patterns of enamel-containing and non-enamel-containing matrix extracts isolated from specific regions within 26-day embryonic New Zealand White rabbit incisor and molar tooth organs. 3. Since enamel proteins become mineralized on secretion, matrix specimens were demineralized in cold 5% (w/v) trichloroacetic acid, extracted with buffered 6M-urea and reduced with mercaptoethanol, and then the solubilized proteins were fractionated by urea/polyacrylamide-gel electrophoresis. 4. Three enamel-specific electrophoretic components were identified in newly secreted enamel-matrix specimens and this number increased as a function of mineralization and maturation. 5. Antibodies were prepared against embryonic rabbit extracellular matrix containing enamel. Comparison between immunoelectrophoretic patterns demonstrated that two of the three enamel components were antigenic. 6. Polyacrylamide-gel electrophoresis in sodium dodecyl sulphate was used to identify four enamel proteins of mol.wts. (1) 65 000 (2) 58000 (3) 22 000 and (4) 20 000, localized within enamel matrix. Enamel proteins (1) and (3) were phosphorylated, whereas (2) and (4) did not contain detectable phosphate. Labelled proline, leucine, tryptophan and glucosamine were incorporated into each of the four enamel proteins extracted from tooth explants incubated in the presence of radioactive precursors for 6 h. Whereas four proteins were identified in newly secreted enamel matrix, the concentrations of high-molecular-weight proteins (1) and (2) were found to decrease and the number (greater than 10) and concentration of low-molecular-weight polypeptides increased as a function of advanced enamel-matrix mineralization and maturation.

Animals↗