Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Statistics as Topic”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 721 records · Page 40Linked to original sources
PubMed2002

Dynamic viscoelasticity of soft liners and masticatory function.

Soft denture liners are used for edentulous patients to cushion functional forces. We hypothesized that the application of soft liners having viscoelastic properties would lead to the most marked improvement in masticatory function. The shear storage modulus (G'), shear loss modulus (G''), and loss tangent (tan delta) were determined for 6 materials by means of a dynamic viscoelastometer. Masticatory function of ten subjects was evaluated by measurements of maximum bite forces and chewing times and frequencies for 2 food samples, and by the use of visual analogue scales. The acrylic materials exhibited viscoelastic behavior, while the silicones exhibited elastic behavior. The improvement in masticatory function compared with hard resin was found to be in the order: acrylic permanent materials > silicone > acrylic temporary materials. The results suggest that the use of materials with higher tan delta and G' provides the most optimum masticatory function for patients requiring the provision of soft liners on their dentures.

Acrylic Resins↗
PubMed2001

Failure of root coverage of shallow gingival recessions employing GTR and a bioresorbable membrane.

The aim of the present study was to compare the postsurgical outcome of two different modes of surgical root coverage of predominantly shallow, Class I or II, gingival recessions. Fourteen facial recessions in nine patients were subjected to a coronally repositioned flap in combination with a bioresorbable membrane, and 14 sites in 13 patients were treated with a connective tissue graft employing an envelope technique. Immediately before surgery and after 6 and 12 months, gingival dimensions as well as root coverage and attachment gain were assessed. At baseline, mean recession depths amounted to 2.77+/-1.67 mm and 2.49+/-1.07 mm for patients treated with a bioresorbable membrane and a free connective tissue graft, respectively. Acceptable and stable root coverage of 81% to 82% of baseline recession depth and 78% of its width was achieved by grafting. In contrast, guided tissue regeneration (GTR) resulted in only 50% coverage of recession depth and, after 12 months, only 11% of its width (P < 0.01). Logistic regression revealed that the odds of obtaining success, ie, at least 80% root coverage, were 3.3 times greater in cases treated with a connective tissue graft (P < 0.05). In addition, the odds ratio was 2.3 in cases of recessions below 2.5 mm compared to deeper recessions and 2 at canines compared to premolars. It was concluded that shallow recessions in the 1.5 to 3.5 mm range should not be treated with GTR. In these situations, predictable results are achieved with free connective tissue grafts employing an envelope technique.

Absorbable Implants↗
PubMedDate not supplied

The effect of oscillation and low seating forces on pulpward pressure transmission and seating during crown cementation: a laboratory study.

PURPOSE: This study investigated the effects of low seating force (5 N) with and without oscillation on pulpward pressure transmission during crown cementation. MATERIALS AND METHODS: Thirty human premolars received standardized complete-crown preparations. They were randomly allocated into three experimental groups of ten: group 1 = 100-N static load; group 2 = 5-N static load; and group 3 = 5-N load with oscillation. Crowns were constructed of base-metal alloy and attached to a purpose-built loading device. Pulpal pressures were recorded using a 0- to 104-kPa pressure transducer that was connected via the sectioned root of the premolar to the pulp chamber, which was perfused with saline driven by nitrogen gas at 83 kPa until a steady rate was achieved. The crowns were cemented using zinc phosphate cement, and postcementation elevations were measured with a linear variable differential transformer. An amalgam condenser provided oscillation for 1 minute. RESULTS: The pulpal pressures were: group 1 = 455 Pa; group 2 = 26 Pa; and group 3 = 76 Pa. The postcementation crown elevations were: group 1 = -48 microm; group 2 = 362 microm; and group 3 = 26 microm. CONCLUSION: Acceptable crown seating can be obtained using low force (5 N) combined with oscillation, and lower pressure pulses are generated compared to using high force (100 N) alone.

Bicuspid↗
PubMedDate not supplied

Severity, distribution, and correlates of occlusal tooth wear in a sample of Mexican-American and European-American adults.

PURPOSE: The objective of this study was to determine the severity, distribution, and correlates of tooth wear in a sample of Mexican-American and European-American adults drawn from a community-based longitudinal aging study on oral health. MATERIALS AND METHODS: The maxillary teeth of 71 subjects enrolled in a longitudinal aging study were assessed using a previously introduced five-point (0 to 4) ordinal scoring system in which each tooth is given a score describing the severity of wear. The tooth wear scores were compared with data concerning demographic factors, functional/parafunctional habits, soft drink consumption, and bite force measurements to determine specific correlates of tooth wear. RESULTS: The mean wear score for all teeth was 1.50 on the five-point scale. There was a significant difference between the mean wear score of anterior teeth (1.85) and posterior teeth (1.17). Bivariate analyses detected a moderate degree of correlation between maxillary tooth wear and age and bite force. Maxillary tooth wear was significantly greater in males and in subjects with reported teeth clenching/grinding. Multivariate analyses revealed that age, gender, bite force, self-reported teeth clenching/grinding, and number of daily meals/snacks had significant correlations with maxillary tooth wear. CONCLUSION: The overall severity of maxillary tooth wear in this sample of Mexican-American and European-American adults was low, with anterior teeth having a greater degree of wear than posterior teeth. Age, gender, bite force, teeth clenching/grinding, and number of daily meals/snacks are potential factors that may have contributed to tooth wear in the study sample.

Adult↗
PubMedDate not supplied

Short-term clinical evaluation of inlay and onlay restorations made with a ceromer.

PURPOSE: This prospective clinical trial evaluated the clinical acceptability of a new material, ceromer, used for inlay and onlay restorations in single- or multisurface cavities of posterior teeth. MATERIALS AND METHODS: Forty-three Targis inlay and onlay restorations were placed in 25 patients and evaluated using the United States Public Health Service criteria. The laboratory work was conducted by three dental technicians according to the manufacturer's recommendations. Twenty-five restorations were luted with Syntac bonding system and Variolink II, and 18 were luted with Scotchbond Multi Purpose and Opal Luting Composite. The recalls were done at 6, 12, and 18 months. Restorations were evaluated for six parameters and scored as ideal (A), clinically acceptable (B), or clinically unacceptable (C). RESULTS: Indirect restorations received, after 18 months, scores of A at the following rates: color match 77%; marginal discoloration 93%; secondary caries 100%; anatomic form 93%; and marginal integrity 95%. For these parameters, statistical analysis indicated no significant differences at baseline and after 18 months. Postoperative hypersensitivity was reported by seven patients at baseline, but it decreased and there was no hypersensitivity at 12- and 18-month follow-ups. CONCLUSION: Over an 18-month period the Targis restorative system yielded good clinical service.

Adult↗
PubMed2002

Dental treatment, dental fear and behaviour management problems in children with severe enamel hypomineralization of their permanent first molars.

OBJECTIVES: To assess the demand for restorative treatment, dental anxiety and dental behaviour management problems among children with severe hypomineralization of their first molars (MIH). DESIGN: Case control study. SAMPLE AND METHODS: Data were compiled from the dental records of 32 9-year-old children with severe enamel hypomineralization of their first molars and from 41 controls of the same age group concerning dental health, a number of restorative treatments, use of local anaesthesia and clinical behaviour management problems (BMP). A questionnaire containing specific questions on children's experiences of dental care and the Children's Fear Survey Schedule-Dental Subscale (CFSS-DS), was answered by the parents. RESULTS: The children in the study group had undergone dental treatment of their first molars nearly 10 times as often as the children in the control group. Repeated treatments of these teeth at brief intervals were common. The dental treatment was often undertaken without the use of local anaesthesia, and BMP, and dental fear and anxiety (DFA) were more common than in the controls. CONCLUSIONS: Children with severe enamel hypomineralization of their first molars had had to undergo a considerable amount of dental treatment. It is reasonable to assume that experiences of pain and discomfort on repeated occasions were related to the occurrence of BMP in patients with MIH. An early treatment planning and prognostication based on increased knowledge of hypomineralized first molars is desirable. Local anaesthesia and other pain-reducing techniques, e.g. sedation, should be used when treating these teeth. Extraction should be considered in cases of extensive disintegration of the crown, in cases of frequently repeated treatments or when pulpal symptoms are hard to cure.

Anesthesia, Dental↗
PubMedDate not supplied

Dental disease indices and caries related oral microflora in children with phenylketonuria.

The purpose of this study was to investigate the dental caries, plaque and gingivitis indices and caries related oral flora in children with classic phenylketonuria. Forty-one children at The Great Ormond Street Hospital for Children and controls were included in the study. The main findings were: No significant difference in the decayed, missing and filled surfaces of the primary and permanent teeth between the phenylketonuria children and the controls. A significantly greater mean plaque score for the control children compared with the phenylketonuria children (p < 0.01) for the permanent teeth only. A significantly greater number of white opacities in the permanent teeth of the phenylketonuria group compared with the control group (p < 0.02). No significant differences in the caries related microflora.

Candida albicans↗
PubMed2001

[Comparison of the cephalometric characteristics of snoring patients and apneic patients as a function of the degree of obesity. Apropos of 162 cases].

BACKGROUND: The purpose of our study was to compare cephalometric analysis of craniofacial features in normal weight or obese subjects who are habitual snorers or apneic. We conducted a retrospective comparison of their clinical and cephalometric features by degree of obesity. PATIENTS AND METHODS: One hundred and sixty two male subjects with obstructive sleep apnea syndrome (OSAS) diagnosed by conventional polysomnography were included in the study. Patients were divided into four groups according to their body mass index (BMI) and their apnea/hypopnea index (AHI: Group 1 = normal-weight snorers (34 patients), Group 2 = normal-weight apneic subjects (40 patients), Group 3 = obese snorers (20 patients), Group 4 = obese apneic subjects (68 patients). Lateral cephalometry was performed in all patients. Intergroup comparisons (2/4, 1/2, 3/4) were made using 32 parameters to study the influence of the size of bone structures, their relationships, and size of the upper airways. RESULTS: The four groups were comparable for age. AHI was higher for group 4 (obese apneic) compared with group 1 (normal-weight snorers). Compared with group 3 (obese snorers), group 1 (normal-weight snorers) had a retroposition of the mandible (smaller SNB and ANB angle), an accentuated facial divergence and a narrower pharyngeal space at the hyoid bone level. Compared with group 1 (normal-weight snorers), group 2 (normal-weight apneic) had a narrower pharyngeal space at different levels. Compared with group 3 (obese snorers), group 4 (obese apneic) had a lower hyoid bone evaluated with different cephalometric variables. CONCLUSION: This study mainly shows that apneic patients exhibit craniofacial differences when divided into two groups according to their body mass index. Our findings are consistent with previous reports and could suggest a dual etiology of OSAS.

Body Mass Index↗
PubMed2001

Effectiveness of three root canal medicaments to eliminate Actinomyces israelii from infected dentinal tubules in vitro.

The persistence of anaerobic bacteria in the root canal system often leads to treatment failure. One possible reason for this may be the retention of micro-organisms in the dentinal tubules of root canal walls. This study was performed to compare the effectiveness of two root canal medicaments and a chlorhexidine solution in disinfecting Actinomyces israelii-infected root canal walls and dentinal tubules in vitro. Dentinal tubules of root canal walls of human teeth were experimentally infected with A. israelii. The root canals were exposed to either iodine potassium iodide, calcium hydroxide or 2% chlorhexidine for periods of 3, 7 and 60 days. At the end of the medication periods samples were removed at different depths and tested for A. israelii viability. Chlorhexidine was the only disinfectant that was able to eliminate A. israelii from all the samples after 3, 7 as well as 60 days while 25% of the specimens treated with iodine potassium iodide and 50% of the specimens treated with calcium hydroxide still had viable A. israelii after treatment. It is clear from this study that 2% chlorhexidine is superior to iodine potassium iodide and calcium hydroxide in its ability to remove A. israelii from infected dentinal tubules. However, in vivo trials need to be undertaken before its clinical use can be recommended.

Actinomyces↗
PubMed2002

Microleakage of a packable composite associated with different materials.

The aim of this in vitro study was to evaluate the extent of marginal leakage with class II composite resin restorations associated with different materials. Twenty extracted sound molars were disinfected and stored in 0.9% saline solution. Four standardized class II cavities were prepared in each tooth, with the gingival margin 1 mm below the cementum-enamel junction. The teeth were then randomly divided into five groups of 16 restorations each: 1) Prime & Bond NT + Surefil; 2) Prime & Bond NT + Dyract Flow + Surefil; 3) Prime & Bond NT + Flow-it + Surefil; 4) Prime & Bond NT + Dyract AP + Surefil; and 5) Fuji II LC + Prime & Bond NT + Surefil. After a storage time of seven days, the restorations were finished and polished. Then specimens were submitted to thermocycling (500 cycles, 5 degrees-55 degrees C, 15 s-dwell time) and immersed in 0.5% methylene blue solution for 24 hours. They were washed and vertically sliced through the middle of the restoration. Both surfaces were evaluated in the gingival margin and one score (0-3) was assigned under a stereomicroscope (40x magnification) by two examiners. The frequency of the scores was evaluated by Kruskal-Wallis and Mann-Whitney tests for pairwise comparisons. None of the associations prevented dye penetration. The statistical analysis showed similar dye penetration among groups 1, 2, 3 and 4 (p > 0.05). The results of penetration in group 5 were significantly lower compared to the other groups (p < 0.05). It was concluded that the use of Fuji II LC as a base material led to the best sealing of the gingival margins based upon the lowest degree of microleakage observed.

Coloring Agents↗
PubMed2002

Comparative efficacy of two battery-powered toothbrushes on dental plaque removal.

A number of clinical studies have consistently demonstrated that power toothbrushes deliver superior plaque removal compared to manual toothbrushes. Recently, a new power toothbrush (Crest SpinBrush) has been marketed with a design that fundamentally differs from other marketed power toothbrushes. Other power toothbrushes feature a small, round head designed to oscillate for enhanced cleaning between the teeth and below the gumline. The new power toothbrush incorporates a similar round oscillating head in conjunction with fixed bristles, which allows the user to brush with optimal manual brushing technique. The objective of this randomized, examiner-blind, parallel design study was to compare the plaque removal efficacy of a positive control power toothbrush (Colgate Actibrush) to an experimental toothbrush (Crest SpinBrush) following a single use among 59 subjects. Baseline plaque scores were 1.64 and 1.40 for the experimental toothbrush and control toothbrush treatment groups, respectively. With regard to all surfaces examined, the experimental toothbrush delivered an adjusted (via analysis of covariance) mean difference between baseline and post-brushing plaque scores of 0.47, while the control toothbrush delivered an adjusted mean difference of 0.33. On average, the difference between toothbrushes was statistically significant (p = 0.013). Because the covariate slope for the experimental group was statistically significantly greater (p = 0.001) than the slope for the control group, a separate slope model was used. Further analysis demonstrated that the experimental group had statistically significantly greater plaque removal than the control group for baseline plaque scores above 1.43. With respect to buccal surfaces, using a separate slope analysis of covariance, the experimental toothbrush delivered an adjusted mean difference between baseline and post-brushing plaque scores of 0.61, while the control toothbrush delivered an adjusted mean difference of 0.39. This difference between toothbrushes was also statistically significant (p = 0.002). On average, the results on lingual surfaces demonstrated similar directional scores favoring the experimental toothbrush; however these results did not achieve statistical significance. In conclusion, the experimental Crest SpinBrush, with its novel fixed and oscillating bristle design, was found to be more effective than the positive control Colgate Actibrush, which is designed with a small round oscillating cluster of bristles.

Adult↗
PubMed2001

Diffusion model of pain language and quality of life in orofacial pain patients.

AIMS: To address the following questions: (1) Which words are preferred by different groups of orofacial pain patients to describe their pain experience? (2) Is it possible, based on such descriptions, to obtain a clinical differential diagnosis in these patients? (3) Is there any relationship between the verbal description of pain and self-rated quality of life (QOL)? (4) Can a pattern of modulation of pain language by affective variables (diffusion model) be recognized in orofacial pain patients, as it has in other chronic pain patients? and (5) If so, what might be the clinical usefulness of assessing pain language in these patients? METHODS: A total of 332 consecutive orofacial pain patients filled out an Italian Pain Questionnaire (the Italian analog of the McGill Pain Questionnaire) and were then divided into 6 diagnostic subgroups (sample 1) based on history and clinical findings. In a double-blind setting, the distribution of pain descriptors and indexes was statistically evaluated. From sample 1, a randomly selected sample of 121 patients (sample 2) also filled out a QOL categorical scale. The results of both tests in this sample were compared statistically. RESULTS: Some significant differences among diagnostic subgroups were found for choice of descriptors and for pain intensity. When a patient's pain description was compared to the corresponding self-evaluation of QOL, a self-perceived worsening of QOL revealed a good correlation with an increase in the number of words chosen, pain intensity, and affective and sensory pain descriptors. A similar significant association was found between self-assessed anxiety and/or depression and the same items. CONCLUSION: Although trends in patients' choice of descriptors were evident, differential diagnosis based on only a pain questionnaire was not possible in the different groups of orofacial pain patients examined in this study. The present study suggests the presence of a phenomenon of diffusion in the language of those patients who were experiencing a worsening of their QOL as a result of pain and consequent psychologic distress. This observation can be of clinical usefulness by enhancing the sensitivity of the clinician to the suffering and affective distress experienced by the patient, and it also can be helpful in refining the therapeutic approach for each individual patient.

Adolescent↗
PubMed2001

Lack of associations between occlusal and cephalometric measures, side imbalance in striatal D2 receptor binding, and sleep-related oromotor activities.

AIMS: First, to evaluate possible orofacial morphologic differences between sleep bruxers and non-bruxers, and second, to determine possible correlations between morphologic factors and striatal D2 receptor expression in persons with sleep-related oromotor activities. METHODS: Twenty subjects were included in this study; half of them had polysomnographically confirmed oromotor values above the cutoff points for sleep bruxism. For all participants, 26 standard occlusal measures were recorded clinically and from dental study casts. In addition, 25 standard angular and linear measures were taken from standardized cephalometric films, and variables were derived to evaluate dental and skeletal relationships. Fourteen of the 20 participants had also participated in a previous study that included iodine-123-iodobenzamide (I-123-IBZM) and single-photon emission-computed tomography (SPECT). For them, the side-to-side difference in striatal D2 receptor binding was determined as the neurochemical outcome measure. RESULTS: Following the classical Bonferroni adjustment for multiple testing, no morphologic differences were found between the sleep bruxers and the non-bruxers. In addition, none of the morphologic variables were significantly associated with the neuroimaging data. CONCLUSION: Taking into account the low power of this retrospective, exploratory study, the results suggest that the orofacial morphology of sleep bruxers does not differ from that of non-bruxers. In addition, morphologic factors are probably not involved in the asymmetry in striatal D2 receptor distribution that was previously observed in association with sleep bruxism.

Adult↗
PubMed2002

The influence of orthodontic bracket base diameter and mesh size on bond strength.

Previous studies have shown that the size of the foil mesh and surface area of the bracket base correlated to bond strength to tooth enamel. The purpose of this study was to investigate the in vitro shear bond strength (SBS) of orthodontic brackets with 80 and 100 gauge mesh bases as well as mini and standard size bases. Eighty extracted human premolar teeth were randomly allocated into four groups of twenty teeth each. Premolar brackets of different mesh and bracket base area sizes were bonded to the enamel with a conventional 'two paste' orthodontic bonding agent. The SBS was determined and the bond failure sites were assessed using light-optical microscope and SEM. Bond failure occurred in all groups primarily at the bracket/adhesive interface. Mean values for SBS were 9.97 +/- 2.94 MPa and 10.72 +/- 2.54 MPa for 80 gauge mini and standard size respectively, and 10.45 +/- 3.27 MPa and 11.39 +/- 3.32 MPa for 100 gauge mini and standard size. A one-way ANOVA and an unpaired t-test revealed no significant difference in mean SBS (P > 0.05) between 80 and 100 gauge mini and standard size brackets, and no significant difference in mean SBS between brackets of the same surface area with a different gauge mesh size. The clinical relevance of this finding is that the clinician can select smaller brackets with no reduction in effectiveness of the treatment procedure.

Adolescent↗
PubMed2002

[Meta-analyses of quarks, baryons and mesons--a "Cochrane Collaboration" in particle physics].

Within the last 20 years meta-analysis has become an important research technique in medicine for integrating the results of independent studies. Meta-analytical techniques, however, are much older. In particle physics for 50 years now the properties of huge numbers of particles have been assessed in meta-analyses. The Cochrane Collaboration's counterpart in physics is the Particle Data Group. This article compares methodological and organisational aspects of meta-analyses in medicine and physics. Several interesting parallels exist, especially with regard to methodology.

Elementary Particles↗
PubMedDate not supplied

Mutans streptococci and lactobacilli in saliva after the application of fissure sealants.

Because dental fissures may serve as reservoirs for mutans streptococci, preventive measures should be taken to control microbial concentrations at these sites. This study estimated the influence that sealing permanent first molars would have on the levels of mutans streptococci and lactobacilli in saliva of healthy seven-year-old schoolchildren. Permanent first molars were sealed in 31 children without caries (NC group) and in 32 children with caries (C group). None of the children had caries in their permanent first molars. Conventional methods were used to count mutans streptococci and lactobacilli in saliva before applying the sealant and again at 4 and 12 weeks after application. Baseline counts of lactobacilli and mutans streptococci were significantly higher in the C group. A significant reduction in mutans streptococci was observed in the NC group at 4 and 12 weeks. It was concluded that fissure sealants in permanent first molars can help reduce salivary levels of mutans streptococci in children without caries.

Child↗
PubMedDate not supplied

Penetrability of dentinal tubules in adhesive-lined cavity walls.

This study investigated the penetrability of dentinal tubules in cavity walls lined with different dentin bonding systems. Occlusal Class I cavities were prepared in 93 premolars. The cavities in the control group had an intact smear layer without a lining, while those in the experimental group were lined with Gluma CPS, Scotchbond Multi-Purpose Plus or One-Step. The penetrability of the dentinal tubules was tested with a dye (basic fuchsin) or bacteria (S faecalis) immediately after adhesive lining and after one-month storage in water at 37 degrees C. Some of the lined samples were sectioned and examined under the SEM. In some samples in the experimental group, the dye penetrated to the pulp and bacteria up to 125 microm into the dentinal tubules immediately after lining. The Kruskal Wallis ANOVA and Tukey test showed the depth of dye and bacterial penetration to be significantly less in teeth with bonding systems than those in the control group (p<0.05). However, there was no statistically significant difference between the control and experimental groups after storage in water (p>0.05). SEM examination showed that the hybrid layer and resin tags were present in the cavity walls immediately after lining but absent after storage in water. Therefore, adhesive linings under the experimental conditions were ineffective in preventing dye or bacterial penetration of the dentinal tubules.

Analysis of Variance↗
PubMed2002

Postoperative mandibular stability after orthognathic surgery in patients with mandibular protrusion and mandibular deviation.

Skeletal stability and temporomandibular joint (TMJ) signs and symptoms were analyzed in 23 patients in whom mandibular protrusion and mandibular deviation had been corrected using bilateral sagittal split ramus osteotomy (BSSRO group, n = 10) and unilateral SSRO and intraoral vertical ramus osteotomy (USSRO+IVRO group, n = 13). Miniplate fixation was used in SSRO but no fixation was used in IVRO. The ratio of condylar bony change was 30.4% (7/23) and all condylar bony changes were seen on the deviated side. All preoperative signs and symptoms of TMJ disorders (4/13 patients in the USSRO+IVRO group and 2/10 patients in the BSSRO group) disappeared after surgery. Comparing the USSRO+IVRO group and the BSSRO group, in patients without condylar bony change, the mandible in both groups was stable anteriorly and horizontally after surgery, even though there was a larger horizontal mandibular movement in the USSRO+IVRO group during surgery. Comparing patients with condylar bony change versus no condylar bony change in the USSRO+IVRO group, postoperative horizontal mandibular displacement was significantly larger in the condylar bony change group than in the no condylar bony change group. These results support the idea that USSRO+IVRO can be useful in correcting mandibular deviation as well as improving signs and symptoms of TMJ disorders. However, it also seems important to be aware of the possibility of horizontal mandibular relapse in patients with condylar bony change.

Adolescent↗