PubMed Health⌕ Search

Biomedical subjects

P L Sadowsky

Publications and source records attributed to P L Sadowsky.

12 recordsLinked to original sources
PubMed1992

Temporomandibular joint sounds and condyle/disk relations on magnetic resonance images.

This study compared the condyle/disk relationships on magnetic resonance images (MRIs) in a group of subjects with completely silent temporomandibular joints (TMJ) when tested clinically with those in subjects with readily discernible TMJ sounds. The sounds were recorded with an accelerometer as the transducer. Selected degrees of jaw separation were electronically determined and recorded with interocclusal wafers for use with the imaging process. Of the "silent joints" 89% were found to have sounds when tested with the accelerometer. These "subclinical" sounds tended to be of shorter duration and occurred at a greater degree of vertical opening than the clinically discernable sounds. The MRIs of the group with clinically discernable sounds tended to show a change in the relationship between the head of the condyle and the intermediate zone of the disk, at the degree of jaw separation of the sound occurrence, whereas no condyle/disk change occurred in the group with "clinically silent joints." It is likely that all joints create sound during function. The different characteristics of the subclinical sounds versus the clinical sounds may indicate differing sound origins.

Adult↗
PubMed1990

Effects of etchant concentration and duration on the retention of orthodontic brackets: an in vivo study.

Etching of enamel before the bonding of orthodontic attachments is usually done with a solution of 37% H3PO4 for 60 seconds. The purpose of this study was to evaluate the effects of etchant concentration and duration on the clinical retention of bonded orthodontic attachments. Two randomly selected groups of orthodontic patients participated in the study. In both groups, teeth in contralateral quadrants, excluding the molar teeth, were bonded. In the first group, 158 teeth were etched with a solution of 37% H3PO4 for 60 seconds, and 155 teeth were etched with 37% H3PO4 for 15 seconds. In the second group, 196 teeth were etched with 37% H3PO4 and 196 teeth with 15% H3PO4, both for 60 seconds. Conventional edgewise mechanotherapy was used in both groups of patients. After 24 months of treatment, in the first group, 8 brackets were dislodged when etched with 37% H3PO4 for 60 seconds and 9 when etched with 37% H3PO4 for 15 seconds. In the second group, 6 brackets were dislodged when etched with 37% H3PO4 for 60 seconds and 13 were dislodged when etched with 15% H3PO4 for 60 seconds. Reducing the etching time of 37% H3PO4 from 60 seconds to 15 seconds or reducing the acid concentration from 37% to 15% H3PO4 applied for 60 seconds had no significantly different effect on the retention of bonded orthodontic attachments. The results suggest that the reduction of etchant concentration and the duration of etching in orthodontic bonding should be considered.

Acid Etching, Dental↗
PubMed1989

Effects of phosphoric acid concentration and etch duration on the shear bond strength of an orthodontic bonding resin to enamel. An in vitro study.

The purpose of this in vitro study was to determine the effects of phosphoric acid (H3PO4) concentration and duration of etching on the shear bond strength of an orthodontic bonding resin to enamel. Nine bonding procedures, each involving 18 extracted human maxillary permanent canines, were used. Ground enamel surfaces were etched with a 37% H3PO4 solution, a 15% H3PO4 gel, or a 5% H3PO4 solution for 60, 30, and 15 seconds, respectively. Cylinders of an orthodontic bonding resin, Concise, were prepared in a special device. The test specimens were disassembled 15 minutes after preparation and stored in distilled water at 37 degrees C for 24 hours. A shear load was applied to the bonded cylinders at a crosshead speed of 0.02 in.min-1 in an Instron testing machine, and the shear bond strengths were calculated and expressed in MN.m-2. A two-factor analysis of the data showed that the H3PO4 concentration had no significant effect on the shear bond strength, but the duration of etching affected shear bond strength significantly. The enamel aspects of the fractured test specimens were examined microscopically and the percent failure within the bonding resin at the bonding sites estimated. The correlation between shear bond strength and percentage failure within the bonding resin was not significant. The effects of the nine etching procedures on ground and unground enamel surfaces were studied by scanning electron microscopy. The etching procedures produced well-defined etching patterns on both ground and unground enamel surfaces.

Acid Etching, Dental↗
PubMed1984

Variability in three morphologic features of the permanent maxillary central incisor.

Variability in tooth morphology can play a significant role in appliance design and the achievable results of orthodontic treatment. This investigation was undertaken to determine quantitatively the variation in three anatomic features of the maxillary central incisor. The three features are the crown-root angulation in a labiolingual direction, the angle formed by a tangent to the middle of the labial surface of the crown and the long axis of the crown from a proximal view, and the lingual curvature of the crown from a proximal view. Tracings of maxillary central incisors were made from two different sources. The first source consisted of radiograms of 98 extracted central incisors, and the second source was a group of 100 cephalometric radiograms which were part of pretreatment records of patients in the Orthodontic Department. The cephalometric radiograms included 25 Angle Class I, 25 Class II, Division 1, 25 Class II, Division 2, and 25 Class III malocclusions. The first measurement taken was the angle formed by the long axis of the crown and the long axis of the root. The second measurement was the angle formed by the long axis of the crown and a tangent to the midpoint of the labial surface of the crown. For the third measurement, the lingual curvature of the crown was described by a mathematical equation whose parameters were used for comparisons. The results revealed a wide range of variation in the three features measured. The mean crown-root angle for Class II, Division 2 malocclusions differed significantly from that for Class II, Division 1 and Class III malocclusions.(ABSTRACT TRUNCATED AT 250 WORDS)

Cephalometry↗
PubMed1983

Acid resistance of enamel exposed to fluoride-containing orthodontic cements.

In a previous study enamel fluoride uptake from fluoride-containing orthodontic cements was evaluated after a 21-day period. The enamel fluoride uptake from a zinc phosphate cement (A), a zinc phosphate cement containing 5 per cent stannous fluoride by weight (B), and a silicophosphate cement (C) was compared. The results indicated that there was a net loss of fluoride from enamel beneath the orthodontic bands cemented with A while the enamel beneath B and C acquired significant amounts of fluoride. The purpose of the present study was to evaluate enamel fluoride uptake after 12 weeks and the effect of the fluoride uptake or loss by the enamel on acid resistance. Five teeth each had bands cemented with cements A, B and C, respectively, and were individually suspended in synthetic saliva for 12 weeks at 37 degrees C. Following this period the bands were removed, the cements were carefully cleaned off the teeth, and the crowns of the teeth were individually suspended in a lactic acid buffer at pH 4 for 4 weeks. Each tooth crown was then sectioned longitudinally and examined microradiographically to study the degree of enamel demineralization. Characteristic subsurface enamel carieslike lesions were noted on all the specimens studied. The carieslike lesions in the enamel exposed to the fluoride-containing cements were considerably reduced. The enamel which had acquired fluoride from the fluoride-containing cements was apparently more resistant to artificial caries attack.

Acids↗
PubMed1976

A comparative study of some dental cements used in orthodontics.

It is suggested that decalcification occurring beneath orthodontic bands is, among other factors, related to the tensile bond strength of the cement to the enamel surface, its marginal leakage at the enamel-cement interface, and its solubility and and disintegration. Under the laboratory conditions described in this study the composite cement exhibited the greatest tensile bond strength to both enamel and band material. The composite cement also displayed no marginal leakage at the enamel-cement interface and showed no solubility or disintegration under the experimental conditions. It could therefore be anticipated that, of the four cements evaluated in this study, the composite cement would have the greatest potential for eliminating pathologic enamel decalcification occurring beneath orthodontic bands.

Composite Resins↗
PubMed1975

Clinical experience with the acid-etch technique in orthodontics.

The acid-etch technique and the development of improved composite resin systems have made the direct bonding of orthodontic attachments an accepted clinical procedure. This technique can be used with confidence as an adjunct in the armamentarium of the orthodontist.

Adolescent↗