[Memorandum on metallic removable prosthesis. Fundamental principles of the casting technique on the model].
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Dental Casting Technique↗
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Evaluation of orthodontists' perception of treatment need and the peer assessment rating (PAR) index.
This paper examines the relationship between orthodontists' subjective assessment of treatment need and objective measurements obtained during standardized intra- and extraoral examinations. Logistic regression modeling was used to develop predictive models of treatment need. Data were obtained from 1155 eighth-grade students by four orthodontists who used standardized examination forms to assess demographics, trauma, skeletal relationships, morphologic malocclusion traits, and mandibular function. At the conclusion of the examination, the orthodontist rated the subjective treatment need as none, elective, recommended, soon, or immediate. For some analyses, the categories were collapsed to represent no need and need. The peer assessment rating (PAR) index (American validated version) was computed from the clinical exam findings and scoring of dental models; PAR scores were used to document malocclusion severity and treatment difficulty. Spearman rank correlation coefficients quantified the relationship between PAR scores and need categories. Logistic regression analysis modeled treatment need using components of the PAR index as well as other variables. The components of these models, as well as sensitivity and specificity, were compared with malocclusion severity/treatment difficulty scores obtained from malocclusion assessments using the PAR index. The five subjective treatment need categories and the PAR index scores were significantly correlated (rho = 0.62, p<0.001). Significant differences were detected between the need and no need groups for all PAR components (p<0.001). PAR index scores and predicted probabilities from logistic regression models performed equally well for classification purposes (no need, need). The data suggest that the PAR index is highly correlated with orthodontists' subjective assessment of treatment need when that assessment is made in the absence of financial considerations and patient desires.
Adolescent↗
Pont's Index as applied on Indians.
One hundred dental models of normal occlusion were evaluated to check the reliability of Pont's Index on a North Indian population. It was concluded by the present study that significant correlations were found to exist between the combined maxillary incisor widths and the maxillary intermolar and interpremolar arch widths.
Bicuspid↗
Orthodontic camouflage versus orthognathic surgery in the treatment of mandibular deficiency.
Clearly, there are postpubertal patients with Class II malocclusions for whom orthognathic surgery combined with orthodontics is the "best" option, but epidemiologic information suggests they are a relatively small percentage of the potential patient pool. The majority of patients fall into either an orthodontic treatment group or a borderline category. Many of these can be treated successfully with orthodontic camouflage. Research has shown psychosocial factors play a major role in determining the patient's selection of a treatment option. This emphasizes the need for careful attention to global psychologic factors, with special emphasis on patient concerns regarding body image. Morphometric criteria have been offered describing appropriate candidates for orthodontic camouflage. These are supported by a combination of research and clinical experience. Patients who do not fit these criteria should not automatically be considered candidates for surgery. Psychosocial research suggests a percentage of these individuals place less importance on facial change and are content to improve dental esthetics and function to the degree possible. To assist in the decision-making process, patients should be given the best information available regarding potential outcome. Currently this may involve treatment simulation using a combination of computer images and dental models. Caution has been suggested, given the variability associated with predicting soft tissue change. There are additional legal concerns regarding the implied guarantee of treatment outcome. Correspondingly, the influence of this technology must be kept in perspective. Recent research on the decision-making process found computer imaging to be an important factor in only 24% of the patients studied.(ABSTRACT TRUNCATED AT 250 WORDS)
Decision Making↗
[The influence of antiseptic solutions used against AIDS on dental waxes, shellac bases, impression compound and zinc-oxide eugenol paste].
The influence of four antiseptic solutions on some dental materials was examined in this study. The antiseptic solutions were sodium chloride 10%, alcohol 75%, Cidex and Sterile pack fluid, whereas the dental materials were dental modelling wax, impression compound, shellac base plate and zinc-oxide eugenol paste. The change of weight and the change of length which were observed in 40 minutes were measured. According to our results the modelling waxes, as well as the impression paste are not influenced by the antiseptic solutions. The impression compound must not be sterilised in Sterile pack fluid, which dissolves it, but it can be floated in the rest of the solutions. The shellac base plates are influenced by all the antiseptic solutions studied, especially by alcohol 75% and Sterile pack fluid.
Acquired Immunodeficiency Syndrome↗
Immediate versus delayed midface distraction in a primate model using a new intraoral internal device.
The theoretic advantage of distraction osteogenesis of the craniofacial skeleton, especially in cases of severe midface retrusion and in the presence of maxillary scarring, is prevention of relapse following significant advancements. The purpose of this study is to demonstrate the utility of a new low-profile, intraoral, internal device for midface distraction at the conventional or high Le Fort I level. In addition, the present study compares the efficacy of immediate versus delayed distraction on subsequent maxillary relapse. Four adult rhesus Macaca mulatta monkeys were divided into two groups. Group 1 underwent immediate midface distraction; group 2 underwent delayed distraction. All four monkeys underwent a modified Le Fort I osteotomy through an upper buccal sulcus incision and bilateral application of the intraoral midface distraction devices. No other osteotomies or incisions were necessary. Immediate distraction, performed in group 1, entailed intraoperative activation of the devices and distraction of 10 mm followed by a 5-day lag period before postoperative activation and distraction of an additional 10 mm at the rate of 1 mm/day. Delayed distraction, performed in group 2, entailed a 5-day postoperative lag period before device activation and distraction of 20 mm at the rate of 1 mm/day. Both groups thus underwent 20 mm of midface distraction. All devices were removed 6 weeks after completion of distraction. All monkeys tolerated the devices and daily distraction uneventfully. On the basis of serial cephalograms and dental models obtained throughout the experimental period, there was no evidence of relapse in either the immediate or delayed groups 6 months after distraction. In addition, on the basis of histologic, ultrastructural, and dry skull analysis, no significant differences were observed in the quality of regenerate bone obtained when comparing the immediate and delayed distraction groups. Significant midface advancement is thus feasible using this new internal, intraoral distraction device, which presents several advantages over other internal devices that require coronal incisions and additional osteotomies to achieve midface advancement. In addition, immediate distraction may abbreviate the distraction period without adverse sequelae.
Animals↗
A relationship measurement method for the analysis of complete unilateral cleft lip and palate cases.
A new graphic method, easily applicable, for the geometric analysis of the dental models of complete unilateral cleft lip and palate cases was developed. Twenty-five unilateral cleft lip and plate patients, in the age group six to twenty years, who had all been surgically corrected by the Lannelongue-Pichler vomer-flap for the hard palate, were analysed with this new method, as well as with two other known methods, the Index System and the Direct Measurement System. The results of all 3 analyses were discussed and compared. No significant differences in the results could be distinguished between these three methods. The advantages of this new method are mentioned, and the geometric data, regarding the influence of the Lannelongue-Pichler surgical technique on arch form, are listed.
Adolescent↗
The effect of extracellular polysaccharides from Streptococcus mutans on the bactericidal activity of human neutrophils.
Extracellular polysaccharides (PS) synthesized by oral bacteria constitute one of their major virulence factors. The PS, synthesized from sucrose, facilitate adhesion and colonization by bacteria to tooth surfaces. The study was designed to test the effect of in situ production of extracellular PS by Streptococcus mutans on the bactericidal activity of human neutrophils. These effects were tested on bacteria pre-exposed to sucrose (PS-positive Strep. mutans) and compared to bacteria not exposed to sucrose (PS-negative Strep. mutans). The interactions between neutrophils and Strep. mutans were tested in suspension and on bacteria in an experimental model of dental plaque. Viability of Strep. mutans was measured by [3H]-thymidine incorporation into the bacteria. Degranulation of neutrophils was evaluated by the release of lysozyme, and the production of reactive oxygen products was measured by chemiluminescence. When neutrophils were incubated with suspended bacteria, the viability of PS-negative Strep. mutans was 20% of that of bacteria not incubated with neutrophils (control), while the viability of PS-positive Strep. mutans was 40% of the control. In the experimental dental-plaque model, 50% of the PS-negative Strep. mutans were killed by neutrophils while the viability of PS-positive Strep. mutans was not different than of the control. Degranulation of neutrophils was not affected by the presence of extracellular PS of Strep. mutans. Artificial stimulation of neutrophils with phorbol myristate acetate also did not enhance the bactericidal effect of neutrophils on PS-positive Strep. mutans. However, PS-positive Strep. mutans elicited oxygen-reactive products from neutrophils, 2-fold less than with PS-negative Strep. mutans. The results indicate that in situ production of bacterial extracellular polysaccharides might be a major virulence factor of Strep. mutans, enabling PS-positive Strep. mutans in the dental-plaque biofilm to evade killing by human neutrophils.
Anti-Bacterial Agents↗
Stereophotogrammetric analysis of casts of normal and abnormal palates.
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Acrocephalosyndactylia↗
A cost analysis of orthodontic in-office and commercial laboratory output.
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Costs and Cost Analysis↗
A subcortical approach to swallow pattern therapy.
The neuromuscular facilitation technique was experimentally used with tongue-thrust patients in order to examine the results of application of this technique to such a population. Four boys and seven girls with a mean age of 116 months were referred by orthodontists in the greater Detroit area to Children's Hospital of Michigan. Each had previously been diagnosed as manifesting tongue thrust. Brushing, icing, and pressure were applied in a home training program for 6 months. Serial dental models were made at 0,3,6 and 12 months, the latter being used to detect regression 6 months after termination of the therapy regimen. Results are presented to support the contention that neuromuscular facilitation is a useful technique in swallow pattern therapy. Ancillary findings are presented which support the contention that mouth breathing and thumb and finger-sucking precede the onset of tongue thrust.
Adolescent↗
Tooth morphology and lower incisor alignment many years after orthodontic therapy.
The dental models of seventy-seven orthodontically treated patients were evaluated to determine the contribution of lower incisor tooth dimensions to their alignment many years after treatment. Tooth dimensions included the maximum mesiodistal (MD) and faciolingual (FL) dimensions and the shape ratio represented by MD/FL. Incisor alignment was assessed by means of Little's irregularity index, and all measurements were recorded to the nearest 0.1 mm with modified dial calipers. Multiple regression analysis revealed that the total contribution of all these lower incisor dimensions accounted for only 7.4% of the variability in their alignment, which was not statistically significant. A similar lack of association between lower incisor tooth dimensions and their alignment was found in a sample of eighty-six adults with untreated malocclusions. It therefore appears that the size and shape of the lower incisors do not significantly contribute to their alignment many years after orthodontic treatment.
Adult↗
Tumors of the facial skeleton in children. Growth patterns after maxillectomy and mandibulectomy.
Thirteen children who had major extirpative surgery of the maxilla or the mandible were followed up an average of five years postoperatively. They ranged in age from three months to eleven years. Facial and oral photographs, cephalograms and cephalometric analysis, and plaster dental models were used to document longitudinal and cross-sectional growth patterns; Our experiences in this limited number of cases has indicated the following: (1) Extensive extirpation of facial bones may be performed in children without significantly jeopardizing function or growth. (2) The roots of healthy teeth may be resected without fear of their noneruption or early loss; loss of sensation with continued viability is the rule. (3) The use of an iliac bone crib with particulate grafts has proved a highly successful means of reconstruction of the mandible in children. (4) Particulate bone has proved to be an effective means of reconstructing large contour defects of the mandible caused by enucleating large tumors in children.
Cephalometry↗
Transfer records for transmitting casts to the laboratory.
Accurate cast relationships are necessary to send a cast to the laboratory when transfer records are used. The technique described eliminates errors which might develop when unstable materials are used for record making and cast relating. The disadvantage is increased laboratory time. Approximately 45 minutes are required to fabricate each record.
Denture Design↗
The relationship between open margins and margin designs on full cast crowns made by commercial dental laboratories.
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Crowns↗
Saw modification for underside die cutting.
A simple modification of a standard laboratory saw and the work bench surface enhances the saw's overall usefulness for sectioning casts. When using these modifications, the operator has a clear view of the preparation margin and the saw blade at all times, thereby permitting accurate, controlled cuts to be made from the underside of a removable pinned die section.
Denture Design↗
Removable prosthodontic laboratory survey.
This article presents a brief review of the literature concerning the curriculum deemphasis for removable prosthodontics, especially on the subject of complete dentures. The authors surveyed commercial dental laboratories specializing in removable dental prosthetics in three major Texas cities to determine whether dentists were submitting adequate records and information with their complete denture work authorizations. Results indicate that dentists are requesting services from their laboratories without providing adequate records.
Dental Occlusion↗
Dynamic mechanical analysis of two crosslinked copolymer systems.
OBJECTIVES: This research investigated the dynamic mechanical properties of two model dental restorative copolymers to elucidate the influence of pendent group length and addition of crosslinking agent. METHODS: Two different monomethacrylate resins [(methyl methacrylate (MMA) or 2-ethoxyethylmethacrylate (EEM)] were added to various molar fractions (0, 5, 10, 20, 40, 60, 80 and 100%) of a difunctional monomer [triethylene glycol dimethacrylate (TEGDMA)], resulting in two different copolymer systems (TMMA and TEEM). Bar-shaped specimens were heat-cured and tested for their dynamic mechanical properties at a fixed frequency (1Hz): flexural storage modulus and loss factor. Transition temperatures associated with peaks were determined using tan delta, phase angle and loss factor. The properties of one specimen were also examined using a range of applied frequencies. RESULTS: Below the Tg, all resin systems had similar storage moduli. An increase in pendent group length lowered transition temperatures and demonstrated greater influence on temperature changes than did a change in crosslinker content. With increasing crosslinker, the transition temperatures increased. The values ascribed to transition temperatures were dependent upon the analysis method used: tan delta gave highest values, followed by phase angle, with loss factor values the lowest. Storage and loss moduli values and their ratio increased with increasing frequency of applied signal. Loss factor analysis provided the most elucidation of sub-Tg transitions. SIGNIFICANCE: Restorative polymers with specific desired physical and mechanical properties can be achieved by both judicious selection of monomer structure as well as by the controlled addition of the crosslinking agent.
Analysis of Variance↗