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Biomedical subjects

R S Nanda

Publications and source records attributed to R S Nanda.

At least 37 records · Page 2Linked to original sources
PubMed1998

Orthodontists' assessment and management of patient compliance.

This study was designed to evaluate the use of predictors and methods of improving patient compliance. A survey of 118 items was developed by searching the literature for items that other researchers have found to be significant. The new questionnaire contained six sections. Sections 1 and 2 pertained to predictors of patient compliance; sections 3 and 4 related to methods of improving compliance. In section 5, the respondents were asked to evaluate patient personality traits that might be important in evaluating compliance, and in the last section, demographic background information on the respondents was collected. Questionnaires were mailed to 1,262 practicing orthodontists in the United States, and 429 responses were received. Patient-related items, such as desire for treatment and relationship with parents, were ranked as important factors motivating patients to comply. Verbal praise and communication were rated as important methods for improving compliance. Personality traits that orthodontists found to be predictive of patient compliance were: high self-esteem; obedient; accommodating; and self-confident. Patients' perceptions of their malocclusions, combined with their desire for orthodontic treatment, may be good indicators of compliance. Doctor-patient rapport and verbal praise may be useful ways to improve compliance.

Appointments and Schedules↗
PubMed1998

Effect of behavior modification on patient compliance in orthodontics.

The purpose of this study was to evaluate the effects of a reward system for improving patient compliance in orthodontic treatment. The sample consisted of 144 orthodontic patients (63 male, 81 female, average age 12.8 years), 6 to 12 months into their treatment. The sample was divided into above-average and below-average compliers, based on the orthodontic patient cooperation scale (OPCS). Each group was further divided into three subgroups: (a) a control group, which received only standard instructions; (b) an award group, which received compliance instructions and a written evaluation of compliance; and (c) a reward group, which received compliance instructions, a report card, and eligibility to receive rewards for adherent behavior. Two measurements of patient compliance were used: (1) the OPCS, which divided the sample into high and low compliers and was used to compare compliance before and after the 6-month experimental period; and (2) a clinical evaluation of compliance that was based on oral hygiene, appointment punctuality, appliance wear, and appliance maintenance. Evaluations were completed at each monthly appointment. Average compliance scores of above-average compliers showed no significant improvement with rewards. The average scores of patients with below-average compliance did not improve significantly. Only oral hygiene scores in the low compliance reward group were better than in the low compliance control group. Academic performance in school was found to be correlated (p < 0.001) with compliance. Above-average compliers remained above average in their compliance. The award/reward system may help motivate below-average compliers to comply with prescribed instructions.

Achievement↗
PubMed1997

In vitro evaluation of matrix-bound fluoride-releasing orthodontic bonding adhesives.

Sustained fluoride-releasing composite resins have the potential to prevent decalcification of enamel that may occur during the course of orthodontic treatment. The purpose of this study was to evaluate the potential of matrix-bound fluoride-releasing adhesives (MBF) for orthodontic use by comparing the shear bond strengths (in MPa) and remnant adhesive on debonding (ARI scores) of these resins with commercially available orthodontic adhesives. Two types of resins were evaluated in separate groups: The light-cured resins (group I) consisted of two light-cured MBF, designated resins LA and LB, and five nonfluoride releasing resins, designated LC, LD, LE, LF, and LG. The self-cured resins (group II) consisted of one MBF, designated resin SA, and six nonfluoride releasing resins, designated resins SB, SC, SD, SE, SF, and SG. These resins were used to attach upper right central incisor metal (foil mesh based) orthodontic brackets to 210 freshly extracted bovine incisors in groups of 15 each. Student-Newman-Keuls multiple comparison tests were performed at p < 0.05 to determine significant differences among the resin types. Resin LA was significantly higher in bond strength (mean = 27.4 MPa) compared with LD and LG (mean = 18.9, 10.7 MPa, respectively). Further, LA demonstrated a higher mean bond strength compared with LB, LC, LE, and LF (mean = 21.9, 24.1, 24.3, and 20.8 MPa, respectively). Resin LB had significantly lower ARI scores (mean = 0.33) compared with LF and LG (mean = 1.20 and 1.80). LA, LB, LC, LD, and LE (mean = 0.47, 0.33, 0.60, 0.73, and 0.73, respectively) were not significantly different in their ARI scores. Resin SB demonstrated significantly lower bond strength (mean = 17.2 MPa) compared with SC, SD, SE, SF, and SG (mean = 23.9, 23.7, 23.4, 23.8, and 22.9 MPa, respectively). Resin SA (mean = 19.0 MPa) was not significantly different in bond strength from SB, SC, SD, SE, SF, and SG. Resin SA demonstrated significantly lower ARI scores (mean = 0.73) compared with SD and SE (mean = 2.13 and 1.87). Resin SA had lower mean ARI scores compared with SB, SC, SF, and SG (mean = 1.00, 1.27, 1.13 and 0.87, respectively). Sustained fluoride-releasing (matrix-bound) orthodontic adhesive systems demonstrated bond strength and ARI scores that compared favorably with commercially available orthodontic adhesives.

Adhesiveness↗
PubMed1997

The effect of different bonding and debonding techniques on debonding ceramic orthodontic brackets.

Previous studies have indicated that different bonding and debonding techniques affect the removal or detachment of polycrystalline ceramic brackets that use a mechanical mechanism of bonding to resin. The delamination type debonding forces have been shown to be more effective, compared with twisting and tensile type forces. Further, polycrystalline brackets bonded by the indirect techniques debond leaving minimal filled resin on the tooth surface and hence cleanup and enamel damage are minimized. The purpose of this research was to compare the effects of three bonding and debonding techniques on debonding two types of ceramic brackets, using different modes of bonding. The monocrystalline bracket used the chemical and the polycrystalline bracket used the mechanical mechanisms for bonding respectively. Brackets were bonded to 180 freshly extracted bovine teeth, divided into two groups of 90 each, based on the bracket employed, i.e., monocrystalline and polycrystalline brackets. These brackets were bonded with the direct and two different indirect bonding methods: the conventional indirect method (modified Thomas) and the indirect technique that used a thermally cured resin. Each bonding group was further divided into three groups of 10, based on the type of debonding technique used, i.e., lift off, delamination, and twisting. The variables evaluated were bracket failure and remnant adhesive on debonding. The data were subjected to an analysis of variance to determine existence of significant differences, followed by multiple comparisons of means. Bracket failure or fracture was significantly affected, based on the bonding technique and the debonding technique for the monocrystalline at p < 0.0001 and the polycrystalline ceramic brackets at p < 0.001 and p < 0.05, respectively. Remnant adhesive was significantly affected by bonding and debonding techniques for the polycrystalline brackets at p < 0.0001. Remnant adhesive was significantly (p < 0.01) affected by the bonding technique for the monocrystalline brackets. The delamination debonding technique combined with the thermal-cured indirect bonding technique was shown to be a safe combination for debonding both types of ceramic brackets. Therefore both bonding and debonding techniques significantly affect bracket failure or fracture and remnant adhesive of ceramic orthodontic brackets during the debonding procedure.

Analysis of Variance↗
PubMed1997

Evaluation of frictional resistance in esthetic brackets.

The purpose of this study was to measure the frictional forces generated between composite, ceramic, and metal brackets and selected wire alloy-size combinations with elastomeric and stainless steel ligatures in a dry environment. Four types of composite, one ceramic, one sapphire, and one metal bracket were tested with stainless steel, nickel-titanium, and beta-titanium wires. The testing was performed with two wire sizes in the 0.018-inch slot brackets and three wire sizes in the 0.022-inch slot bracket. The recently introduced composite brackets were found to offer lower frictional resistance than the ceramic and stainless steel brackets, regardless of the wire size, wire alloy, and type of ligation. The wire alloy with the least friction was stainless steel, followed by beta-titanium and nickel-titanium. Mean variability in friction, as reflected by the magnitude of the standard deviations, was 2.7 to 3 times more with the stainless steel ligation than the elastomeric ligation.

Bicuspid↗
PubMed1997

Forces produced by lip bumpers on mandibular molars.

The purpose of this study was to measure the forces produced by a lip bumper on the mandibular permanent first molars. The forces in a sample of 38 patients were measured bilaterally with specially designed gauges at rest but with their lips lightly touching, speaking the words church, phone, and pop, and swallowing water. Forces were compared between two types of lip bumpers, i.e., wire or shield, and between various anteroposterior and vertical positions of the lip bumper. The resting forces produced by the wire lip bumper 2 mm anterior to the incisors and vertically positioned at the middle of the incisor crown were 5.93 +/- 4.84 gm for the left side and 4.66 +/- 4.8 gm for the right. The forces were found to be significantly higher when the wire lip bumper was placed 4 mm anterior to the incisors and at a more gingival position, measuring 16.68 +/- 8.7 gm for the left side and 13.88 +/- 8.28 gm for the right. The shield lip bumper had higher forces both at the center of the incisor as well as when it was positioned gingivally. A large individual variation was observed. There were no statistically significant differences in force levels between male and female subjects. Speaking the words church, pop, and phone, produced forces between 11 and 23 gm, using a wire lip bumper. Swallowing produced the highest forces, between 32 and 36 gm. Lip thickness and height did not appear to affect the force levels.

Acrylic Resins↗
PubMed1997

Stiffness-deflection behavior of selected orthodontic wires.

Treatment of horizontal and vertical tooth discrepancies requires wires of low stiffness to produce forces as the teeth are leveled and aligned. In this investigation, the stiffness characteristics of several solid and multistrand nickel-titanium and stainless steel orthodontic wires were determined at selected clinically relevant deflections. Twenty specimens of 24 different wires were tested in both three-point and three-bracket bending modes. The unloading force deflection plot of each wire was described by a polynomial regression from which wire stiffnesses were obtained by mathematical differentiation. Graphs of the functional relationship between stiffness and deflection are presented. The results of this investigation show that wire stiffness can be altered not only by changing the size, but also by varying the number of strands and the alloy composition. An equally important finding was the dependence of stiffness on deflection for most of the wires measured. Comparisons were also made between the stiffness values obtained in three-point bending and the three-bracket bending systems.

Dental Alloys↗
PubMed1997

Esthetic orthodontic appliances and bonding concerns for adults.

This article has described application of bonding procedures for adults in everyday practice. Depending on the materials and the technique employed, one can achieve satisfactory bonding. The techniques used to debond orthodontic brackets safely have been described. The bonded retainer, particularly in the mandibular arch, can easily be applied using the technique described. These retainers offer an advantage because of the high patient acceptance owing to convenience and esthetic reasons. Bonding on porcelain veneers and gold crowns has been described. Although silane pretreatment to the porcelain surface yields satisfactory results, the technique for bonding to gold has not yet been fully perfected.

Adult↗
PubMed1996

Perceived orthodontist behaviors that predict patient satisfaction, orthodontist-patient relationship, and patient adherence in orthodontic treatment.

Orthodontist-patient relationships have significant effects on the success of orthodontic treatment. The purpose of this study was to evaluate the effects of patient-perceived orthodontist behaviors on (a) patient perceived orthodontist-patient relationship, (b) patient satisfaction, and (c) orthodontist-evaluated patient adherence or compliance in orthodontic treatment. The sample consisted of 199 orthodontic patients, 94 boys and 105 girls, ages 8 to 17 years, who were recruited at the beginning of orthodontic treatment by a member of the research team who was not involved in treating the patients. The patients were asked to complete standardized questionnaires in a room away from the orthodontic clinic, 8 to 12 months into treatment. At the same time, the orthodontic resident treating each patient completed a standard instrument that evaluated patient compliance. Orthodontist behavior items such as politeness, friendliness, communicativeness, and empathy were evaluated by the patients. Stepwise multiple regression analyses (p < 0.05) showed that eight behaviors predicted perception of the orthodontist-patient relationship (final model R2 = 0.7930 and 0.7333) as well as patient satisfaction (final model R2 = 0.7952) and two behaviors predicted patient compliance (final model R2 = 0.0986). Of the 24 orthodontist behaviors, 22 were significantly correlated (p < 0.0001) with favorable orthodontist-patient relationship and patient satisfaction. Of the 24 behaviors, 10 were significantly correlated (five at p < 0.01 and five at p < 0.05) with patient compliance. Patient-perceived orthodontist behaviors are related to and predict (1) patient perceived orthodontist-patient relationship, (2) patient satisfaction, and (3) orthodontist-evaluated patient adherence or compliance.

Adolescent↗
PubMed1996

Frictional resistances in stainless steel bracket-wire combinations with effects of vertical deflections.

This research evaluated the effects of different bracket-wire combinations and second-order deflections on kinetic friction. Thirteen different brackets, six with 0.018 x 0.025 inch slots and seven with 0.022 x 0.028-inch slots were evaluated with six different sizes and shapes of stainless steel orthodontic wire, i.e., 0.016, 0.016 x 0.022, 0.017 x 0.025, 0.018, 0.018 x 0.025 and 0.019 x 0.026 inch for four second order deflections of 0.00, 0.25, 0.50, and 0.75 mm. The wires were ligated into the brackets with elastomeric modules. Bracket movement was implemented by means of an Instron universal testing instrument (RMO, Denver, Colo.), and frictional forces were measured by a tension load cell and recorded on an X-Y recorder (Hewlett-Packard, Anaheim, Calif.). Second-order deflection was created by a specially designed and machined testing apparatus that allowed two alternate pairs of the four total brackets to be offset in increments of 0.25 mm. The kinetic frictional force increased for every bracket-wire combination tested as the second-order deflection increased. Friction also increased with an increase in wire size, whereas rectangular wires produced greater friction than round wires. Bracket designs that limited the force of ligation on the wire generated less friction at low second-order deflections (0.00 and 0.25 mm).

Dental Stress Analysis↗
PubMed1996

The effects of exogenous prostaglandin E2 on root resorption in rats.

This study evaluated the amount and depth of root resorption associated with varying concentrations and frequencies of injectable, exogenous prostaglandin E2 (PGE2) in conjunction with orthodontic tooth movement in rats. The sample consisted of 155 maxillary right and left first molars from 88, 8-week old, male Sprague-Dawley rats. The animals were divided into three control groups and two experimental groups. The control animals were divided into one nonappliance and two appliance groups. The experimental animals were divided into 2- and 4-week experimental time periods that were further subdivided based on single and weekly injection intervals of PGE2 and four different injectable concentration levels, i.e., 0.1, 1.0, 5.0, and 10.0 micrograms. A fixed orthodontic appliance was ligated between the maxillary incisors and maxillary first molars with closed-coil nickel-titanium springs. The appliance had an initial activating force of 60 gm. Serial histologic sections of the mesial root of the maxillary first molar were made, and a quantitative histomorphometric analysis of root resorption on the mesial and distal surfaces was performed. This study demonstrated increased root surface resorption when using exogenous PGE2 injections to enhance orthodontic tooth movement over a 2-week period with increasing root resorption on the mesial surface as compared with the distal surface in PGE2 treated teeth. No differences in root resorption were found with either multiple injections or increasing concentration in the 4-week experimental group. Local injection of PGE2 appeared to have no effect on the number or depth of resorption lacunae in either the 2- or 4-week groups.

Analysis of Variance↗
PubMed1996

A study of force application, amount of retarding force, and bracket width in sliding mechanics.

We investigated the relationship of the retraction force to the location of force application, retarding force and bracket width during simulated sliding tooth movement along an arch wire. Point 1 for retraction was located at the center of the bracket, and points 2 and 3 were at 4.0 mm and 6.0 mm from the bracket slot, respectively. Weights of 100 gm, 200 gm, and 400 gm were suspended at 9.0 mm from the bracket slot as the point of simulated center of resistance. Stainless steel standard edgewise wide, medium, and narrow twin brackets were engaged with two elastomeric ligatures on a stainless steel wire (0.016 x 0.016 inch). The bracket was retracted at the rate of 0.1 mm per second for a distance of 2.0 mm. Measurements were repeated six times, and the results were compared with multiple ANOVA tests. For all brackets, with an increase of the retarding weight, the mean retraction force at points 1 and 2 increased but decreased at point 3. The mean retraction force at point 1 for the narrow twin bracket was significantly (p < 0.05) higher than that for the wide twin bracket at all retarding force levels. However, the mean retraction force at points 2 and 3 for the narrow twin bracket was significantly (p < 0.05) lower than for the wide twin bracket at all retarding force levels. These findings indicated that the point of force application, the resistance force of a tooth, and the width of the bracket are crucial in consideration of the tipping moments on the bracket.

Analysis of Variance↗
PubMed1996

A longitudinal cephalometric study of the soft tissue profile of short- and long-face syndromes from 7 to 17 years.

The longitudinal growth and development of the soft tissue drape for boys and girls with long and short vertical patterns was examined from age 7 to 17 years. The sample was taken from the Denver Growth Study and consisted of 32 subjects who were selected on the basis of their percentage of lower anterior vertical face height. All subjects were of northern European ancestry, and none had undergone orthodontic treatment. The sexual dimorphism was evident as anticipated for several soft tissue measurements. The boys showed continued growth through age 16 years in contrast to the girls who attained the adult size of the soft tissue integument around 14 years. A significant difference between vertical facial patterns was reported for all soft tissue variables with the exception of the soft tissue thickness at A point and the upper lip height. The boys and girls with long vertical patterns exhibited a thicker and longer soft tissue drape for the most variables when compared with those with short facial patterns. These soft tissue differences are believed to be compensatory mechanisms in long-face subjects, which may attempt to mask the vertical dysplasia, thereby producing a more normal facial profile. Individual growth assessments revealed that the perioral soft tissues follow a pattern similar to that of the mean group patterns. The subjects with long vertical facial patterns experienced their pubertal growth spurt earlier than the short-face subjects. This may have clinical implications in the timing of orthodontic intervention and treatment.

Adolescent↗
PubMed1996

Evaluation of an intraoral maxillary molar distalization technique.

The purpose of this study was to determine the effects of the pendulum appliance on distalization of maxillary molars and the reciprocal effects on the anchor premolars and maxillary incisors. Initial and follow-up cephalometric radiographs were obtained on 41 subjects (26 girls and 15 boys) who were treated with the pendulum appliance for bilateral distalization of the maxillary first molar teeth, for correction of the Class II molar relationship or for gaining space in the maxillary arch. Dental casts were available on 31 patients. Dental, skeletal, and soft tissue changes were determined. The mean maxillary first molar distalization was 3.37 mm, with a distal tipping of 8.36 degrees. The mean reciprocal mesial movement of the first premolar was 2.55 mm, with a mesial tipping of 1.29 degrees. The maxillary first molar position intruded 0.1 mm, whereas the first premolar extruded 1.7 mm. The transverse width between the mesiobuccal cusps of the first molars increased 1.40 mm. The maxillary second molars were also distalized 2.27 mm, tipped distally 11.99 degrees, and moved buccally 2.33 mm. The effect of distalization on the maxillary third molars was extremely variable. The eruption of maxillary second molars had minimal effect on distalization of first molars. The lower anterior face height increased by 2.79 mm. This increase was greater in patients with higher Frankfort-mandibular plane angle measurements. The pendulum appliance is an effective and reliable method for distalizing maxillary molars, provided the anchor unit is adequately reinforced. Its major advantages are minimal dependence on patient compliance, ease of fabrication, one-time activation, adjustment of the springs if necessary to correct minor transverse and vertical molar positions, and patient-acceptance.

Adolescent↗
PubMed1996

Class II, Division 1 malocclusion treated with molar distalization therapy.

A case report of an 11-year-old black girl with a Class II, Division 1 malocclusion is presented. There was associated lip incompetence and excessive display of gingiva on smiling. Nonextraction treatment was undertaken with distalization of maxillary molars to correct the Class II relationship. [This case was presented at the annual session of the American Association of Orthodontists held in Orlando, 1994. This was part of the University of Oklahoma, Department of Orthodontics participation in the display of patients treated by graduate students sponsored by the College of Diplomates, American Board of Orthodontics.]

Cephalometry↗
PubMed1996

Tomographic assessment of temporomandibular joints in patients with malocclusion.

There is a paucity of information on the morphological assessment of the temporomandibular joint in relation to varying skeletal and dental relationships. The purpose of this study was to evaluate the morphologic relationship of the condyle and fossa in patients with different malocclusions and skeletal relationships. Pretreatment records of 232 orthodontic patients, 95 males and 137 females, of Caucasian descent and ranging in age from 9 years 4 months to 42 years 6 months, were examined. Records included dental casts, lateral cephalometric radiographs, hand-wrist radiographs, and corrected tomograms of right and left TM joints. Nonconcentricity and mild asymmetry of the condyle-fossa relationship were commonly observed. The left condyle was found to be more anteriorly positioned than the right, with the mean percentage of joint space being 6.93% on the left side and -1.24% on the right. Skeletal and dental Class III patients demonstrated significantly more anteriorly positioned condyles (P < 0.05). There were no significant differences in condylar position between Class I and Class II groups based on ANB or Angle's classification. Further, no significant difference in condylar position was observed between groups based on overbite or crossbite.

Adolescent↗
PubMed1996

Three-dimensional facial analysis using a video imaging system.

The purpose of this article was twofold: (1) to provide an estimate of error in the digitization of various soft tissue landmarks using a video imaging system, and (2) to evaluate the relationships of various soft tissue measurements in balanced young adult faces. A video imaging system was used to digitize frontal and lateral soft tissue landmarks on 25 male and 25 female Caucasian young adults with Class I occlusion and esthetically pleasing and balanced soft-tissue profiles. Twenty subjects were redigitized and only two measurements showed a statistically significant error. Large variabilities were found for several measurements. Males, in general, had greater soft tissue thickness, facial depth and width, and lip length than females. The measurements were found to compare favorably with previous reports. Imaging systems were seen to have the advantage of providing reliable measurements in all three dimensions without the potential hazards of ionizing radiation.

Adult↗