Showing papers in "Journal of Dental Research in 1981"
TL;DR: Bone morphogenetic protein (BMP) made by the process comprising the steps of demineralizing bone tissue; treating the demined bone tissue under aqueous conditions with a water soluble neutral salt and a solubilizing agent for the BMP, the agent being selected from the group consisting of urea and guanidine, and thereby transforming the bone collagen to gelatin and extracting BMP into the solution of solubiliizing agent as mentioned in this paper.
Abstract: Bone morphogenetic protein (BMP) made by the process comprising the steps of demineralizing bone tissue; treating the demineralized bone tissue under aqueous conditions with a water soluble neutral salt and a solubilizing agent for the BMP, the agent being selected from the group consisting of urea and guanidine, and thereby transforming the bone collagen to gelatin and extracting BMP into the solution of solubilizing agent; and separating the solubilizing agent and neutral salt from the solution, thereby precipitating BMP in the aqueous medium, and the BMP has a molecular weight in the range of 1,000-100,000.
1,292 citations
332 citations
TL;DR: Evaluating the ability of agents used previously for clinical dentin desensitization to reduce the rate of fluid flow through dentin in vitro provided a useful quantitative method for screening a host of preparations that have been used in the past to decrease dentin sensitivity.
Abstract: The hydrodynamic theory of dentin sensitivity states that a stimulus applied at the orifice of exposed dentinal tubules causes movement of tubular fluid which stimulates nerve receptors. The fluid should obey principles of fluid movement through capillary tubes. Any decrease in the functional radius of the dentinal tubules should greatly reduce the rate of fluid flow, thus reducing dentinal sensitivity. The purpose of this study was to evaluate the ability of agents that have been used previously for clinical dentin desensitization to reduce the rate of fluid flow through dentin in vitro. Dentin discs prepared from extracted human third molars were treated with 50% citric acid to remove debris from tubular orifices. After placing the discs in a split chamber device, the rate at which buffer solution could filter across the dentin under 240 cm of water pressure was measured. The occlusal side of the disc was then treated with an agent thought to desensitize dentin to determine if it reduced fluid flow rate. Discs that had more than a 50% reduction in flow rate were examined by scanning electron microscopy to determine if those agents that decreased fluid flow also partially occluded tubular orifices. This in vitro model provided a useful quantitative method for screening a host of preparations that have been used in the past to decrease dentin sensitivity.
285 citations
TL;DR: Of subjects taking medication, post-menopausal women (but not older men) produced stimulated saliva at rates significantly lower than their non-medicated counterparts.
Abstract: The production of stimulated parotid saliva was examined in 208 adults, aged 23-88 yr. Among men and women, taking no prescription medication, there was no diminution of stimulated parotid fluid output with increased age. Of subjects taking medication, post-menopausal women (but not older men) produced stimulated saliva at rates significantly lower than their non-medicated counterparts.
229 citations
TL;DR: A degradation of untreated fillers in composites stored in distilled water was indicated by an increased sodium and hydroxy ion concentration in storage water, and by examination of the fillers with SEM.
Abstract: A degradation of untreated fillers in composites stored in distilled water was indicated by an increased sodium and hydroxy ion concentration in storage water, and by examination of the fillers with SEM. Silane treatment of the fillers retarded the leaching process, while cycling stresses accelerated it.
204 citations
TL;DR: The development, alveolar emergence, and agenesis of the mandibular third molars, in a homogeneous group of French-Canadian children and young adults ranging in age from seven to 25 yr, were evaluated from 4640 panoramic radiographs using the method of Demirjian et al.
Abstract: Bilateral agenesis was encountered in about 9% of the cases, with no significant sexual difference. The right and left mandibular third molars had the same pattern of development and emergence. The slight advance of girls over boys at the crown-completion stage was similar to previous observations on other mandibular teeth, particularly the second molar. The root development course of the third molar was faster in males than in females; this sexual dimorphism was much greater for retarded cases than for advanced cases. At the apex closure, the difference between median ages of males and females was 1.5 yr. Alveolar emergence tended to occur at a lower developmental stage in advanced cases compared with retarded cases.
173 citations
TL;DR: The visible emission spectra and fluorescent lifetimes from decayed and nondecayed regions of teeth were measured and compared and may offer a non-X-ray method for diagnosing dental caries in humans.
Abstract: The visible emission spectra and fluorescent life-time from decayed and nondecayed regions of teeth were measured and compared. The spectrum from carious lesions is different from that of noncarious tooth regions. This may offer a non-X-ray method for diagnosing dental caries in humans.
168 citations
TL;DR: In situ dental amalgams can increase the level of mercury in expired air, and examined subjects with dental amalgAMS had higher pre-chewing mercury levels in their expired air than those without amalgams.
Abstract: The expired air of a group of 48 persons, 40 with and eight without dental amalgam restorations, was analyzed for its mercury content before and after chewing. Expired air samples were collected in polyethylene bags, and a known quantity of each was pumped into the mercury detector for measurement. The results showed that examined subjects with dental amalgams had higher pre-chewing mercury levels in their expired air than those without amalgams. After chewing, these levels were increased an average of 15.6-fold in the former and remained unchanged in the latter group. It was concluded that in situ dental amalgams can increase the level of mercury in expired air.
160 citations
TL;DR: An adhesive opaque resin containing 4-methacryloxyethyl trimellitate anhydride was prepared for use with acrylic veneer crowns, and its bond strength and durability of adhesion with an alloy were studied.
Abstract: 1) A new adhesive opaque resin containing a reactive monomer, 4-methacryloxy-ethyl trimellitate anhydride (4-META), was prepared, and its application to thermosetting acrylic resin veneer crowns was studied. 2) The 4-META opaque resin was applied to a variety of nickel-chromium dental alloy specimens which had undergone different treatment, and endurance tests were conducted to evaluate the durability of adhesion. 3) Stable adhesion against water penetration was achieved with metal surfaces first etched with HCl and then oxidized with HNO3. A bond strength of 250 kg/cm2 was maintained even after immersion in water at 37 degrees C for 30 wk or at 80 degrees C for ten wk. Furthermore, this value did not decrease even after the specimens were subjected to 500 thermal cycles. 4) The 4-META opaque resin studied can eliminate the necessity for retention devices on metal castings. 5) The smooth 4-META opaque resin should have no adverse effects on gingivae.
150 citations
TL;DR: It was observed that the cracks emanating from the comers of an indentation propagated preferentially, with the weakest path of fracture usually extending along the cervical-incisal axis.
Abstract: A microindentation technique was employed to estimate the fracture toughness of human enamel. A pattern of increasing fracture toughness values existed from incisal to cervical in incisor enamel. Statistical analysis indicated that the molar enamel was more brittle than either the canine or incisor enamel. It was observed that the cracks emanating from the comers of an indentation propagated preferentially, with the weakest path of fracture usually extending along the cervical-incisal axis.
138 citations
TL;DR: The contrast ratio, light reflectivity, scattering coefficient, and absorption coefficient of four composites and an unfilled resin were calculated algebraically from reflection spectrophotometric data using Kubelka's equations to derive contrast ratio and values of infinite optical thickness.
Abstract: The contrast ratio, light reflectivity, scattering coefficient, and absorption coefficient of four composites and an unfilled resin were calculated algebraically from reflection spectrophotometric data using Kubelka's equations The correlation coefficient between calculated and experimental values of contrast ratio was 09996 Values of infinite optical thickness ranged from 419 to 670 mm
TL;DR: Comparisons between patients wearing bands and patients just prior to banding on the basis of treatment and/or dental caries history found patients with a history of caries had significantly higher levels of S. mutans in plaque than did their non-banded counterparts.
Abstract: The effect of orthodontic banding on the prevalence of Streptococcus mutans in plaque was evaluated by comparisons between patients wearing bands and patients just prior to banding on the basis of treatment and/or dental caries history. Banded patients had significantly higher levels of S. mutans in plaque than did their non-banded counterparts. Regardless of banding, patients with a history of caries had significantly higher levels of S. mutans in plaque and greater numbers of S. mutans-infected sites than did caries-free patients. Caries-free banded patients had more S. mutans-infected sample sites than did the caries-free non-banded group.
TL;DR: Translucency of human dental enamel was determined by total transmittance of wavelengths from 400 to 700 nm and the decrease in translucency occurred as a result of the replacement of water around the enamel prisms by air during dehydration.
Abstract: Translucency of human dental enamel was determined by total transmittance of wavelengths from 400 to 700 nm. The transmission coefficient at 525 nm was 0.481 mm-1. Total transmission of light through human dental enamel increased with increasing wavelength. Human tooth enamel is more translucent at higher wavelengths. The translucency of wet human enamel and enamel after dehydration was also measured by total transmittance. The transmission coefficient at 525 nm decreased from 0.482 to 0.313 mm-1 after dehydration and was reversed on rehydration. The decrease in translucency occurred as a result of the replacement of water around the enamel prisms by air during dehydration.
TL;DR: Cell kinetics of rat molar periodontal ligament (PDL) during orthodontically-induced osteogenesis revealed that cell death is a characteristic feature of the osteogenic response.
Abstract: Cell kinetics of rat molar periodontal ligament (PDL) during orthodontically-induced osteogenesis revealed: 1) primary growth fraction of 59%, 2) proliferating cells from throughout the PDL migrate toward the bone surface, 3) preosteoblasts, capable of forming osteoblasts without synthesizing DNA, are present in the PDL, 4) osteoblasts are derived from local PDL cells, and 5) cell death is a characteristic feature of the osteogenic response.
TL;DR: DBP did not undergo appreciable resorption prior to bone formation and was a more potent osteogenic stimulus than was BP or lyophilized chips.
Abstract: In order to investigate the repair of mandibular defects, we have devised a nonhealing model in the ramus of the rat mandible. The large full thickness defects, devoid of periosteum, were filled with demineralized bone powder (DBP), lyophilized bone chips, and un-demineralized bone powder (BP) or were irrigated with Ringer's lactate. Healing was judged by gross and histologic examination and by incorporation fo 45 calcium into hydropyapatite. DBP produced more rapid and complete healing than did BP or lyophilized chips. DBP did not undergo appreciable resorption prior to bone formation and was a more potent osteogenic stimulus than was BP or lyophilized chips.
TL;DR: The toxicity of local anesthetic drugs is usually due to inadvertent rapid intravascular injection or extravascular administration of an excessive amount, and signs and symptoms of CNS excitation followed by depression are the most common manifestations.
Abstract: Local anesthetic agents may be classified according to their intrinsic anesthetic potency and duration of activity. Procaine and chloroprocaine are relatively weak, short-acting drugs. Lidocaine, mepivacaine, and prilocaine represent agents of intermediate potency and duration of action. Tetracaine, bupivacaine, and etidocaine are highly potent, long-acting agents. The toxicity of local anesthetic drugs is usually due to inadvertent rapid intravascular injection or extravascular administration of an excessive amount. Intravascular toxicity is correlated with intrinsic anesthetic potency, whereas toxicity following extravascular injections is a function of physiological disposition characteristics of the various agents, such as rate of vascular absorption, rate of tissue redistribution, and rate of metabolism. The central nervous system is most susceptible to the toxic effects of local anesthetic agents. Signs and symptoms of CNS excitation followed by depression are the most common manifestations of local anesthetic toxicity. Cardiovascular depression may also occur following administration of excessive doses of local anesthetic agents or following high spinal or epidural anesthesia.
TL;DR: Dip-slide cultivation for salivary lactobacillus and yeast growths revealed that both stimulatedSalivary flow rate and pH are related to the presence of yeasts.
Abstract: This study demonstrates that the presence of yeast, but not lactobacillus infection, is related to salivary flow rate Salivary pH is correlated with the primary infection of both lactobacilli and yeasts The low output of saliva appears to influence the quantity of lactobacilli more than that of yeasts The flow rate was lower and the presence of yeasts was higher in females than in males
TL;DR: A theoretical investigation has utilized the finite element technique to analyze mechanical stress patterns in a reconstructed maxillary central incisor and results show that minor changes in the stress patterns are produced by the post diameter, length, and taper variations considered.
Abstract: A theoretical investigation has utilized the finite element technique to analyze mechanical stress patterns in a reconstructed maxillary central incisor. A series of designs for endodontic dowel posts incorporated into the prostheses has been comparatively evaluated. For the load condition considered, the results show that minor changes in the stress patterns are produced by the post diameter, length, and taper variations considered.
TL;DR: Loads at the articulating surface of the head of the condyle were recorded in one male adult Macaca arctoides following surgical implantation of the pressure-sensitive foil following hard and soft foods to chew.
Abstract: This paper describes a novel technique of directly measuring loads at the condyle in Macaca arctoides and provides recordings on one animal while measuring loads at the TMJ. This study is the first to actually measure loads directly at the articulating surfaces of the condyle. The data collected in this study confirm Hylander's data that the TMJ is a stress-bearing joint. With this pilot study, observations which can be made are: 1) The loads at the condyle are minimal during posterior chewing of both soft and hard foods (1-3 lb), and 2) during mastication of food the load (3-4 lb) at the condyle is larger than for posterior chewing. It was demonstrated during the calibration of the transducer that as the condyle translates forward over the articulating eminence during opening, a load is produced on it which is as large as the load present during incisal biting. Since recordings were only successfully taken on one animal, the above observations must be confirmed with further experiments.
TL;DR: The relationship between the severity of periodontitis and PMNChemotactic abnormalities in diabetics and nondiabetics was evaluated and the observed PMN chemotactic defects with the degree of gingival inflammation and the amount ofperiodontal attachment loss was correlated.
Abstract: There is widespread belief that diabetes mellitus predisposes to the development of severe periodontitis by reducing the resistance of the periodontium to local irritations. Several investigators (Lavine et al., J Periodont Res 14:10-19, 1979 and Van Dyke et al., Infect Immun 27:124-132, 1980) have demonstrated impairment of the chemotactic response of polymorphonuclear neutrophilic leukocytes (PMN's) in juvenile and rapidly progressing periodontitis patients. These observations have implicated impaired PMN chemotaxis as a major factor in the predisposition of patients to severe periodontal destruction. In contrast, Shurin et al. (N Engl J Med 301:829854, 1979) related the alterations in PMN chemotaxis to the presence of Capnocytophaga species in the dental plaque of a patient with juvenile periodontitis. Impaired PMN chemotaxis in diabetic patients has been reported previously (Mowat, A.G. and Baum, J., N Engl J Med 284:621-626, 1971), and it has been suggested that this impairment is genetically determined (Molenaar et al., Diabetes 25:880-883, 1976). Therefore, this study was undertaken to evaluate the relationship between the severity of periodontitis and PMN chemotactic abnormalities in diabetics and nondiabetics and to correlate the observed PMN chemotactic defects with the degree of gingival inflammation and the amount of periodontal attachment loss. Thirty-two dentulous subjects including 14 insulin-dependent adult onset diabetics and 18 non-diabetics were selected for this investigation. Medical and dental histories were recorded prior to the experiment and complete periodontal examinations were performed; plaque and gingival indices (Loe, H., J Periodontol 38:610, 1967) were recorded. Patients with at least a five-year history of diabetes and fasting blood glucose levels > 140 mg/dl were selected for the study. Non-diabetic subjects demonstrated a normal oral glucose tolerance test and no family history of diabetes. The diabetic group was subdivided into eight subjects with severe periodontitis (mean age 49 yr, range 32-59 yr) and six subjects with absent or mild periodontal disease (mean age 51 yr, range 44-60 yr). The non-diabetic group was subdivided into seven patients with severe periodontitis (mean age 48 yr, range 31-60 yr) and 11 subjects with mild periodontal disease (mean age 32 yr, range 21-50). Subjects in the latter subgroup served as healthy controls to compare the chemotactic response of subjects in the three other subgroups. Severe periodontitis was defined by an average attachment loss of greater than 4 mm and at least six periodontally-affected teeth with more than 50% attachment loss. There was no radiographic evidence or history of past juvenile periodontitis among the subjects. Chemotaxis of purified peripheral PMN's (>98% PMN) was evaluated with a modified Boyden technique as previously described (Baum et al., J Lab Clin Med 77:501, 1971). Briefly, 1.25 x 106 PMN were deposited onto a 3 Mzmillipore filter with a cytocentrifuge. The filter was immediately placed into a Sykes-Moore tissue culture chambert and the upper cell compartment was filled with Hanks' Balanced Salt Solution. § The chemotactic agent was placed in the lower or attractant compartment. The chamber was incubated inverted at 37°C for three h; the filter was removed, stained with hematoxylin, and mounted in the microscopic slide. The chemotactic index (CI) was determined (see Figure). The chemoattractants studied included a) endotoxinactivated sera (EAS) of diabetics, b) EAS of non-diabetics, and c) a synthetic chemotactic polypeptide, n-formylmethionylleucylphenylalanine (FMLP), at 10-7M. Day-to-day variation in the CI of individual subjects was insignificant as previously suggested (Hill et al., JLab Clin Med 86:703710, 1975). In fact, two or three subjects from each subgroup were tested on different occasions yielding similar results. Random migration assessed by chemotaxis toward a buffer control was similar in each subgroup (Table). The CI of diabetics with mild periodontal disease was not significantly different from the CI of non-diabetic controls with either mild or severe periodontal disease, regardless of the chemo-attractant studied. In contrast, the CI of diabetics with severe periodontitis was significantly
TL;DR: Pulpal changes demonstrated evidence of reversibility after 60 d, and hydrogen peroxide alone or with heat caused obliteration of odontoblasts, hemorrhage, resorption, and inflammatory infiltration.
Abstract: Hydrogen peroxide and heat are two components of a technique commonly used to bleach human teeth. The effects of these two components on pulp tissue of dog teeth were evaluated histologically. Hydrogen peroxide alone or with heat caused obliteration of odontoblasts, hemorrhage, resorption, and inflammatory infiltration, while heat alone was not detrimental. Pulpal changes demonstrated evidence of reversibility after 60 d.
TL;DR: In a preliminary investigation, condyle-temporal bone spatial relationships were determined quantitatively in 50 asymptomatic TMJs by making area measurements of the posterior and anterior portions of the joint spaces, indicating that the condyle is normally centered in the joint to a very high degree.
Abstract: In a preliminary investigation, condyle-temporal bone spatial relationships were determined quantitatively in 50 asymptomatic TMJs (25 subjects) by making area measurements of the posterior and anterior portions of the joint spaces. For both right and left sides, the numerical expression of the joint relationship indicated that the condyle is normally centered in the joint to a very high degree. Standard deviations around the mean joint relationship values were large, however, which suggests that the posteroanterior variation of condyle positions in asymptomatic TMJs is greater than commonly thought. In addition, there was only mild correlation between individual joint relationships on right and left sides.
TL;DR: Carbonate increased the reactivity of hydroxyapatite, which resulted in an increased rate of dissolution and a decreased activation energy for dissolution for the carbonated apatites.
Abstract: A series of synthetic carbonated and non-carbonated apatites was investigated using high resolution transmission electron microscopy, and their dissolution behavior was tested under sink conditions, using the rotating disc method. n-Beam lattice images of the apatite samples were of a resolution greater than has been previously reported, and revealed an increase in crystalline disorder with the incorporation of carbonate in the apatite structure. This resulted in an increased rate of dissolution and a decreased activation energy for dissolution for the carbonated apatites. Thus, carbonate increased the reactivity of hydroxyapatite.
TL;DR: Characteristics differentiating two groups of adolescents were identified: those planning orthodontic treatment and a comparison group not planning treatment, and eighty-two percent of the subjects were correctly categorized using the resulting discriminant function.
Abstract: Overall, these results support the view that dental-facial esthetics and self-perceptions of occlusal appearance, as well as attitudes toward malocclusion and orthodontic treatment, are important factors in the individual's decision to obtain orthodontic treatment. The data indicate that psychosocial variables not directly related to occlusal problems and treatment, do not add significantly to the description of differences between those who seek treatment and those who do not. While these analyses did not include a number of variables--such as socioeconomic factors or attitudes of significant others--which may also be important in predicting individual response to malocclusion, they do suggest strongly that psychosocial factors directly related to need for treatment are probably most productively assessed in terms of self-perceptions of occlusal appearance and attitudes regarding dental malrelations and their treatment.
TL;DR: The data presented suggest that the levels of organic phosphates as a limiting factor in the initiation of mineralization of bone in vitro is not as limiting factor as previously thought.
Abstract: Calvarial periostea were dissected from 17-day-old embryonic chicks and folded with the osteogenic cells in apposition. The folded explants were cultured for up to six d on serum and plasma clots or in serum-free hormone-supplemented completely-defined medium. Osteoid consistently formed in such cultures in both types of media, and this osteoid mineralized when appropriate levels of beta-glycerophosphate were added to each type of medium. The data presented suggest that the levels of organic phosphates as a limiting factor in the initiation of mineralization of bone in vitro.
TL;DR: The major role that saliva plays in modifying plaque pH, especially in caries-resistant people, is demonstrated, as the access to saliva was increased and the observed pH minima increased to a significantly greater degree in the CR subjects than in the CS subjects.
Abstract: The effect of saliva on plaque acidogenesis was studied in ten caries-resistant and ten caries-susceptible subjects. Plaque pH was measured in vivo following exposure to a sucrose substrate under varying conditions of salivary access. Our findings demonstrate that when there is no salivary access, plaque pH levels are similar in the CR and CS groups. As the access to saliva is increased, the observed pH minima increased to a greater degree in the CR subjects than was noted in the CS subjects. This indicates that saliva (notably stimulated saliva) plays a major role in modifying plaque pH and quantitatively reflects caries status.
TL;DR: Fluoridated hydroxyapatites were synthesized at 80 degrees C (pH 7.4) to study their crystallinity and solubility in relation to fluoride content and the crystallinity increased initially, then decreased, and finally increased again with the degree of fluoridation.
Abstract: Fluoridated hydroxyapatites were synthesized at 80 degrees C (pH 7.4) to study their crystallinity and solubility in relation to fluoride content. The crystallinity of fluoridated hydroxyapatities increased initially, then decreased, and finally increased again with the degree of fluoridation, whereas the decrease in relative solubility of fluoridated hydroxyapatites at 25 degrees C (pH 4.0) was proportional to the logarithm of the fluoride content.
TL;DR: The results from this study showed a variety of pulpal responses to various calcium hydroxide materials when placed directly on the dental pulp, and two materials proved to be more successful at stimulating reparative dentin bridging and healing of the underlying pulp tissue.
Abstract: The results from this study showed a variety of pulpal responses to various calcium hydroxide materials when placed directly on the dental pulp. Two of the materials proved to be more successful at stimulating reparative dentin bridging and healing of the underlying pulp tissue. The remainder of the pulp capping agents were ineffective at healing the pulp and forming a reparative dentin bridge. When teeth were capped with these other agents, the pulp showed necrosis and chronic inflammation.
TL;DR: The results indicate that the type ofPDL modeling has a significant effect on the nature and magnitude of alveolar stresses, and that the fibrous PDL modeling shows higher and more widely distributed lateral tensile stresses in the alveolars bone than those resulting from the continuous PDL modeled.
Abstract: Finite element analysis is used to determine the physiological stress values in the natural tooth and the underlying bone. In addition to modeling the periodontal ligament (PDL) as a continuous structure as considered in previous studies, the PDL is modeled more accurately in a novel fashion as a fibrous structure. The results indicate that the type of PDL modeling has a significant effect on the nature and magnitude of alveolar stresses, and that the fibrous PDL modeling shows higher and more widely distributed lateral tensile stresses in the alveolar bone than those resulting from the continuous PDL modeling.
TL;DR: The central dark line observed in enamel crystallites has been studied by transmission electron microscopy and microdiffraction and shows it to be a single 100 plane of the hydroxyapatite structure whose appearance depends on specific diffraction conditions.
Abstract: The dark line which is observed in enamel crystallites represents a planar defect involving a single 100 plane of the hydroxyapatite structure. It may occur in the majority of crystals throughout the enamel, although it is only observed in specific diffraction conditions. Its presence may be related both to the formation and growth of crystallites in the developing tooth and to the manner in which the crystallites dissolve during caries. TEM studies show clearly that the central defect is not a dislocation, stacking fault or lattice twin boundary. They further indicate that it cannot represent a structural twin boundary. The remaining possibilities are that it represents a substitution in the HAP lattice, most likely involving carbonate ion, or a separate compatible calcium phosphate phase.