Prevalence of deep periodontal pockets in New Mexico adults aged 27 to 74 years

The purpose of this study was to describe the distribution of advanced periodontal destruction (pocket depth equal to or deeper than six mm) in continuous residents, aged 27 to 74 years, of Lordsburg and Deming, New Mexico. The distance from the free gingival margin to the base of the gingival crevice or pocket was measured on the facial and mesiofacial sides of six index teeth. The presence of supragingival calculus, subgingival calculus, and plaque, as well as gingival bleeding around the index teeth, also were evaluated. Of the 372 examinees, only 46 individuals (12.4 percent) had at least one deep pocket equal to or deeper than six mm on at least one site on the six index teeth. Age was significantly associated with prevalence of deep pockets, although about 80 percent of those aged 47 to 74 years did not have deep pockets. Of those with deep pockets, 89.1 percent had fewer than four tooth sites (out of 12) affected. The only significant risk factor of the presence of deep pockets, other than age, was the number of teeth with plaque accumulations. Age and the number of teeth with plaque explained only 10.5 percent of the variability in the prevalence of deep pocketing, suggesting that risk factors other than those included in this study may be important. The results of this study indicate that destructive periodontal disease occurs at selected sites within the mouth, and that about 87 percent of the adults over age 27, in this population, do not have deep pockets in the six index teeth examined.     

Development of dental Pd-Ti alloys

Alloys, in which the main constituents are palladium and titanium, have the following potential advantages for dental application: corrosion resistance, biocompatibility and acceptable casting temperatures for porcelainfused-to-metal dental prostheses. Alloy compositions chosen for investigation were as follows: 30 w/o Ti which lies in the 5% single-phase region near TiPd, 50 w/o Ti which lies near the 1120°C melting temperature minimum of the Pd?Ti system, and 70% Ti which minimizes Pd content while still in a relatively low melting range (1300°C). Analysis of the X-ray diffraction of 70%Pd30%Ti showed mostly PdTi with some Pd₅Ti₃; in 50%Pd50%Ti mostly PdTi₂ was observed with some PdTi; in 30%Pd70%Ti mostly PdTi₂ was found with some alpha Ti and PdTi₄. The amounts of the minor phases in each of the 3 alloys depended on heat treatment. The Knoop hardness of the alloys ranged from 300–500 KHN for the as-melted condition; after heat treatment the maximum hardness values were 400 KHN. After centrifugal casting, hardness values increased to a range of 350 to 560 KHN, depending on composition. These values exceed those obtained for the pure metals which were in the neighborhood of 100 KHN. From anodic potentiodynamic scans the breakdown potentials in Ringer's solution for 70%Pd30%Ti, 50%Pd50%Ti and 30%Pd70%Ti were 600, 650 and 500 (SCE); the repassivation potentials for the same alloys are 450, 300 and 350 (SCE), respectively. These are all above oral potential. The Pd?Ti system investigated was, thus, found to have adequate corrosion resistance and hardness. Therefore, it can be considered of good potential as a dental prosthetic alloy.     

Inferior joint space arthrography and characteristics of condylar paths in internal derangements of the TMJ.

Inferior joint space arthrography and measurements of the condylar path provide scientific documentation of derangement of the TMJ disc and condyle. These derangements are described as an anterior displacement of the disk associated with posterior-superior displacement of the condyle when the teeth are closed into the intercuspal position. Clinical studies demonstrate that approximately 70% of a TMJ patient population present with some type or stage of these derangements. These observations have far-reaching implications regarding contemporary dental curriculum, particularly concerning exegesis of the MPD syndrome theory and concepts of dysfunctional dental occlusion.     

Taste acuity of the human palate. III. Studies with taste solutions on subjects in different age groups.

The taste acuity at the midline of the hard and soft palate near their junction and, for comparison, on representative areas of the tongue was determined in 80 subjects aged 11-79 years by applying test solutions of the four basic tastes. Twenty-one subjects (26%) could identify at least one taste on the hard palate but none could recognize all four tastes. Seventy subjects (87%) could identify at least one taste on the soft palate and 37 subjects (46%) could recognize all four tastes. Taste thresholds were much higher on the hard palate than on the tongue and were in most cases higher on the soft palate than on the tongue. The ability to recognize all four tastes was less frequent in older than in younger subjects and the difference was greatest on the soft palate and least at the foliate papillae. The differences were greatest for citric acid and least for sucrose. There was a tendency to lower thresholds for women compared to men for all four tastes on all areas examined which was most pronounced on the soft palate. No differences in taste thresholds were found between denture wearers and subjects with natural dentition. Smokers had higher thresholds than non-smokers only for salt on the soft palate and the base of the tongue.     

The effect of the operator on the clinical performance of amalgam.

In this study, the effect of the operator on the clinical performance of amalgam was examined by evaluating the marginal fracture characteristics of four alloys placed by four operators. The results were as follows: --Marginal fracture was influenced by the operator. Therefore, careful attention should be given to the cavity design and the placement technique. --The interaction between operators and alloys was such that, for the worst alloy, there was no difference caused by the operators; for the intermediate alloys, there were large differences caused by the operators; and for the best alloy (a non-gamma 2 system), there was almost no difference caused by the operators. --The difference in marginal fracture characteristics among alloys was greater than the difference attributed to operators. --It appears that all practitioners should use non-gamma 2 amalgams because such amalgams perform better clinically and are less susceptible to variations in operators.     

The surgical-orthodontic correction of mandibular deficiency. Part II

As discussed in Part I of this study, persons with mandibular deficiency and Class II malocclusions exhibit a wide spectrum of esthetic, cephalometric, and occlusal characteristics. In many such patients optimal overall results are best obtained via a combined orthodontic-surgical approach. In such patients a critical evaluation is essential to decide (1) the optimal operation and (2) the appropriate orthodontic-surgical sequencing. Our method of making these two basic decisions was presented in Part I. In this article the indications for mandibular advancement with or without genioplasty, total subapical mandibular advancement, superior repositioning of the maxilla, and inferior repositioning of the maxilla are discussed in detail. These alternatives are illustrated with representative cases, and the results are discussed. The intention of these two presentations is to illustrate an orthodontic-surgical approach to the correction of mandibular deficiency and Class II malocclusion that is predicated on a systematic evaluation of the individual patient rather than a standard approach.     

An evaluation of commercial pastes for finishing composite resin surfaces

A study was conducted to determine the effectiveness of several commercial pastes in polishing the surfaces of composite resin material. Five samples of Concise composite resin contained within Plexiglas block holders were prepared using Mylar matrices. One block was disked only; three blocks were disked and polished, each with a different paste. The remaining block was the control. The surface roughness of all samples was measured with a stylus profile instrument. Five extracted teeth were prepared in the same manner with Concise composite resin and Mylar strip matrix. In each tooth, the surface was finished by disking only or by disking followed by polishing with one of three pastes. The fifth tooth was the control. The samples were examined by use of a scanning electron microscope. Quantitative evaluation of over-all computer data indicated that the smoothest surface was found immediately ater removal of the Mylar matrix and that pastes leave a rougher surface than is left with a disc.     

A longitudinal study on the effect of unilateral extraction of primary molars.

The effect of unilateral extraction of the first or second primary molar on space conditions, need for orthodontic treatment, and eruption stage of permanent canines and second molars has been studied longitudinally in two groups. In Group 1 the first primary molar had been extracted early in 13 cases in the maxilla and in 14 cases in the mandible. In Group 2 the corresponding figures for the second primary molar were 14 and 24 for the maxilla and mandible, respectively. The space on the extraction side in Group 1 was significantly less than on the control side at the age of 9 but not at the age of 13. In Group 2 there was significantly less space on the extraction side than on the control side at the two registration ages (10.5 and 12 years). Need for orthodontic treatment was low in Group 1 and high in Group 2. As for eruption stage of permanent canines and second molars, no significant differences were found between the extraction side and the control side in the two groups.     

Composite shrinkage stress as a function of specimen dimensions and compliance of the testing system.

OBJECTIVES: Verify the influence of specimen dimensions on composite shrinkage stress in testing systems of known compliance and in situations where axial strain of bonding substrates was suppressed. Stress distribution was evaluated using finite element analysis (FEA). METHODS: A chemically activated composite (Bisfill 2B, Bisco) was inserted between the flat surfaces of two glass rods (2, 4 or 6mm diameter, D) attached to a universal testing machine. Specimen height (H) was defined by adjusting the distance between the rods (0.5, 1, 2 or 4mm). An extensometer was used to monitor the distance between them. Maximum force after 30min of polymerization was divided by the cross-sectional area of the rod to obtain nominal stress (sigma(n)). Mathematical equations were employed in order to estimate the 'corrected nominal stress' (sigma(cor)) that would be obtained in ideally rigid systems. Data were analyzed by two-way ANOVA/Tukey test (alpha=0.05) and regression analysis (stress versus 'C factor' and stress versus specimen volume). Axysimetrical 2D models were used to evaluate X-component stress distribution (sigma(x)) in the zero compliance condition. RESULTS: The interactions between D and H were significant for sigma(n) and sigma(cor) (p<0.001). For D=2mm, height influenced only sigma(cor) values. A direct correlation was found between stress and C factor (sigma(n):R(2)=0.959; sigma(cor):R(2)=0.923), but not between stress and volume. FEA evidenced the effect of boundary restraints on sigma(x). SIGNIFICANCE: Specimen dimensions influenced test results, mostly regarding sigma(cor). Stress values strongly increased with the confinement of the specimen probably due to stress concentration adjacent to the bonded interface.