The relationship between chi-square statistics from matched and unmatched analyses.
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Chi-Square Distribution↗
Biomedical subjects
R G Newcombe
Publications and source records attributed to R G Newcombe.
Inter- and intra-observer variation in the reporting of cervical smears: specialist cytopathologists versus histopathologists.
One hundred and ten cervical smears were circulated to five specialist consultant cytopathologists and five consultant histopathologists. Of these smears, 100 were randomized and re-circulated. The cytopathologists reported endocervical cells and wart virus infection more frequently than the histopathologists, although neither group showed good inter-observer agreement for either assessment. Apart from smear adequacy and the presence of endocervical cells, both groups showed good intra-observer agreement in all the parameters measured. This suggests that overall individuals were applying their own personal criteria with consistency over time, although a previous study had shown considerable lack of inter-observer agreement among the histopathologists on the grade of dyskaryosis and the management recommendation. The results indicate that specialist cytopathologists bring a different viewpoint to the reporting of cervical smears than histopathologists. They also show a lack of standardization in the reporting of smears despite the guidelines issued by the British Society for Clinical Cytology.
Cytodiagnosis↗
Variations in the clinical sulcus depth of healthy human gingiva: a longitudinal study.
Evidence is currently lacking that sulcus depths of fully erupted teeth remain unchanged in the presence of excellent oral hygiene and absence of overt gingival inflammation. In 44 healthy volunteers (age range 16-34 yr) exhibiting the above criteria, sulcus probing depths (PD) were measured with a flexible measuring strip at 6 mesio-buccal (MB) and 6 bucco-cervical (BC) sites on 6 occasions spanning a total period of 20 weeks. Analysis of the data obtained showed that PD had a total range of 0.5-4.5 mm, varying greatly between subjects, although each had a personally characteristic distribution of PD across different sites. Mean depths of MB sites and variations were greater than at BC sites. Fluctuations at BC sites may, however, be no more than measurement error whereas those at MB sites may be real, or may reflect the greater difficulty of access to MB sites than to BC ones.
Adolescent↗
Comparison of three faecal occult blood tests in the detection of colorectal neoplasia.
METHODS AND AIMS: For the detection of colorectal neoplasia, 192 consecutive patients had colonoscopy to evaluate the sensitivity and specificity of three faecal occult blood tests (FOBT). Of 160 evaluable patients (96 female, mean age 51.9), 21 patients (13.1%) had adenomas and three patients (1.9%) had colorectal carcinoma. RESULTS: When comparing all three faecal occult blood tests for the detection of colorectal neoplasia, the sensitivity of Monohaem (43.8%) was superior to both Hemoccult II (25%) and to BM-Test colon albumin (25%). The specificity of Monohaem (94.6%) was greater than both Hemoccult II (88%) and BM-Test colon albumin (89%). Using McNemar's test, Monohaem was a more accurate FOBT than Hemoccult II and BM-Test albumin (p < 0.05). In the 21 patients with adenomatous polyps, FOBT sensitivity seemed to be dependent on polyp size, but not polyp site. CONCLUSIONS: Monohaem, a feacal occult blood test that uses a monoclonal antibody that is specific for human haemoglobin, is a more accurate test in the detection of colorectal neoplasia and should possibly be used in colorectal cancer screening programmes.
Adenoma↗
A comparison of chlorhexidine, cetylpyridinium chloride, triclosan, and C31G mouthrinse products for plaque inhibition.
There are a large number of mouthrinse products available to the general public for use as adjuncts to oral hygiene. Many have not been evaluated and relatively few comparisons of products have been made. This study compared 4 mouthrinse products containing cetylpyridinium chloride (CPC), chlorhexidine, C31G, or triclosan with saline rinse included as a placebo control. Twenty dentate volunteers took part in this 4-day plaque regrowth study which had a single blind, randomized cross-over design balanced for residual effects. On day 1 of each study period, volunteers were rendered plaque free by a professional prophylaxis, suspended normal oral hygiene measures, and rinsed twice daily for 1 minute with 15 mL of the allocated rinse. On day 5, subjects were scored for disclosed plaque by plaque index and plaque area. By both measures the order of decreasing product efficacy was chlorhexidine, CPC and triclosan, C31G, and saline. All the differences in favor of the chlorhexidine product were highly significant as were those in favor of the other rinses compared to saline. It is concluded that the findings of this study reflect the actual chemical benefits of the products divorced from the indeterminate variable of toothbrushing.
Adult↗
The substantivity of a number of oral hygiene products determined by the duration of effects on salivary bacteria.
The persistence of action, or substantivity, of antimicrobial agents in the mouth appears to be a major variable influencing plaque inhibition. Such substantivity can be assessed by measuring the duration and magnitude of suppression of salivary bacterial numbers produced by antimicrobial agents. Although this has been determined for some agents, there is little information on the substantivity of the numerous products which contain these and other antimicrobial agents. This study was commissioned on the basis that efficacy cannot be assumed merely because a product contains a known active agent. Nine formulations or products were chosen: 2 rinses containing chlorhexidine or C31G, 4 rinses containing cetylpyridinium chloride (CPC) (with and without fluoride and/or alcohol), a minus-CPC control rinse, and 2 toothpastes with and without stannous fluoride. Additionally, water was used as a placebo control. Twenty health dentate volunteers took part in this blind, 10 cell randomized, single rinse, cross-over study, which was balanced for carryover. Mouthrinses were 15 ml volumes and toothpastes 3 gm in 10 ml water slurries rinsed for 60 seconds. On the day of each study volunteers suspended oral hygiene habits and at approximately 9:00 a.m. rinsed with the allocated formulation. Unstimulated saliva samples were obtained immediately before and 30, 60, 180, 300, and 420 minutes after rinsing. The samples were immediately processed for total anaerobic bacterial counts. All rinses except water and the minus CPC control rinse produced significant falls in counts to 30 minutes. Of more relevance in this inter-treatment comparison-designed study, the C31G rinse showed significant substantivity compared to water only for 60 minutes. C31G was highly significantly less substantive than chlorhexidine from 30 minutes to 420 minutes. The CPC rinses were similar and significantly more substantive than their control rinse to between 180 and 300 minutes. The stannous fluoride and control pastes were similarly substantive to 300 minutes, with the stannous fluoride paste remaining substantive compared to water to 430 minutes. Based on antimicrobial action these formulations varied considerably in substantivity and this is likely to reflect their comparative plaque inhibitory properties.
Analysis of Variance↗
Transdermal nicotine compared with oral prednisolone therapy for active ulcerative colitis.
BACKGROUND: Ulcerative colitis is largely a disease of non-smokers. Previous controlled trials have shown benefit with transdermal nicotine when given with 5-aminosalicylic acid in active disease but not when given alone as maintenance therapy. OBJECTIVE: To examine nicotine alone compared with prednisolone in active disease. PATIENTS AND METHODS: Sixty-one patients with active ulcerative colitis were treated with either transdermal nicotine patches or 15 mg prednisolone for 6 weeks in a randomized, double-blind study. Incremental doses of nicotine were given for the first 9 days; patients tolerated between 15 and 25 mg daily. Most patients were taking mesalazine at entry which was discontinued at day 10; a few were taking topical steroids which were discontinued at the onset. Clinical, sigmoidoscopic and histological assessments were made at baseline and 6 weeks, or at premature withdrawal. Symptoms were recorded on a diary card, and the clinician made a global clinical assessment. Side effects and serum nicotine and cotinine concentrations were monitored throughout the study. RESULTS: Forty-three patients completed the 6-week trial; of these, 6 of 19 in the nicotine group achieved full sigmoidoscopic remission compared with 14 of 24 with prednisolone (P = 0.08). In those who completed the 6-week study, there was significant improvement within both the nicotine and prednisolone group for the St Mark's score (P < 0.05 and P < 0.01, respectively), Global Clinical Grade (P < 0.01 for both), blood in the stool (P < 0.05 and P < 0.01), abdominal pain (P < 0.05 and P < 0.01) and sigmoidoscopic score (P < 0.01 and P < 0.001); differences between groups tend to favour prednisolone, but none reach statistical significance. However, on intention-to-treat analyses there is little clear evidence of improvement in either group apart from sigmoidoscopic score in which prednisolone was associated with a significantly greater improvement than nicotine (P < or = 0.05). The nicotine group had more withdrawals than the prednisolone group, 11 versus 7, respectively (P = 0.23), both for deterioration (6 vs. 5) and side effects (5 vs. 2, P = 0.15). Side effects were more frequently reported in the nicotine group (average 1.47 episodes per person) than the prednisolone group (average 0.61; P = 0.03), the most common of which were nausea, light-headedness and tremor. CONCLUSION: In those who managed to complete the 6-week study, nicotine alone appeared to be of only very modest benefit in acute colitis and was not as effective as 15 mg of prednisolone daily.
Administration, Cutaneous↗
Transdermal nicotine as maintenance therapy for ulcerative colitis.
BACKGROUND: Ulcerative colitis is largely a disease of nonsmokers. Having found previously that treatment with transdermal nicotine patches and mesalamine (5-aminosalicylic acid) has a beneficial effect on active colitis, we examined the value of transdermal nicotine for the maintenance of remission. METHODS: We treated 80 patients with ulcerative colitis in remission with either transdermal nicotine or placebo patches for six months in a randomized, double-blind study. Incremental doses of nicotine were given for the first three weeks to achieve a maintenance dose; most patients tolerated 15 mg for 16 hours daily. All patients were taking mesalamine preparations as maintenance treatment at entry into the study; this treatment was stopped once the maintenance dose of nicotine was achieved. Clinical, sigmoidoscopic, and histologic assessments were made at the beginning and the end of the study, or at relapse. Side effects and serum nicotine and cotinine concentrations were monitored throughout the study. RESULTS: There was no significant difference in the number of relapses between the groups. Twenty-two patients in the nicotine group were prematurely withdrawn from the study, 14 because of relapse and 8 for other reasons, including side effects and protocol violations. In the placebo group, 20 patients were withdrawn prematurely, 17 because of relapse and 3 for other reasons. Among patients using 15-mg nicotine patches, serum nicotine and cotinine concentrations were lower than expected and may reflect poor compliance. Side effects were reported by 35 patients--21 in the nicotine group and 14 in the placebo group--the most common of which were nausea, lightheadedness, and itching. CONCLUSIONS: Transdermal nicotine alone was no better than placebo in the maintenance of remission of ulcerative colitis, and premature withdrawal due to side effects was more common in the nicotine group.
Administration, Cutaneous↗
Multiflex versus superelastic: a randomized clinical trial of the tooth alignment ability of initial arch wires.
Two arch wires commonly used for initial tooth alignment were compared with regard to their clinical effectiveness. The two arch wires tested were 0.0155-inch diameter multiple-stranded stainless steel wire (Dentaflex, Dentaurium, Optident, Yorkshire, England) and 0.014-inch diameter nickel-titanium alloy wire (NiTi, ORMCO Co., Monrovia, Calif.). Consecutive patients attending an orthodontic clinic for routine placement of a fixed appliance were randomly assigned one of these two initial arch wires. Good quality alginate impressions of the appropriate dental arch were taken before arch wire placement and also at the subsequent appointment, which was, on average, 6 weeks later. Seventy-four arches were used in this study. The degree of tooth alignment achieved for each wire type was compared with a Reflex Microscope (Reflex Measurement Ltd., Butleigh, England) to make detailed measurements on the resultant casts. The degree of initial alignment achieved with the two wires was similar over this 6-week period. However, some differences were found for the lower labial segment where the interbracket span is usually reduced and where the superelastic nickel-titanium wire was found to give improved alignment. No threshold of crowding was found where one arch wire performed better than the other.
Adolescent↗
An assessment of approximal bone height in the posterior segments of 15-16-year-old children using bitewing radiographs.
The alveolar bone height in a total of 713 15-16-year-old children consisting of 364 males and 349 females was assessed using posterior bitewing radiographs. The distance between the alveolar crest (AC) and amelo-cemental junction (ACJ) on all molar and premolar teeth was determined from magnified images of the radiographs. Analyses of variance models were fitted in order to assess the dependence of the overall ACJ to AC distance on the inter-subject variables of gender and social class and the intrasubject variables of site, missing adjacent tooth, condition of the approximal tooth surface, and for mesial surfaces, gingivitis and pocket depth. The overall geometric mean for bone height for the whole population was 0.542 mm. The ACJ to AC distance for the vast majority of sites was below 2 mm. Site had a highly significant effect on bone height (P < 0.001): ACJ to AC distances were greater in the maxilla compared to the mandible (P < 0.001), greater for distal sites compared to mesial (P < 0.001) and significantly affected by tooth type (P < 0.001). Sites with missing adjacent teeth also had significantly increased distances (P < 0.001). The condition of the approximal tooth surface and the presence of pocketing or gingivitis did not have a significant association with bone height. The geometric mean AC to ACJ distance, adjusted for subject, site and social class was 0.577 mm for males and 0.506 mm for females (P < 0.001), but the main effect of social class was not significant.
Adolescent↗
Radiographic amelocemental junction and alveolar crest: effect of X-ray beam angulation.
The effect of X-ray beam angulation on the radiographic images of the amelocemental junction (ACJ) and alveolar crest (AC) and their positions relative to one another were assessed using a new laboratory model for radiographic studies. A total of 39 teeth with 62 usable approximal surfaces were included in the investigation. When all tooth types were combined, changes in vertical or horizontal angulation from baseline through 20 degrees had no significant effect on the distance between the marked (true) ACJ and marked (true) AC. However, the distance between the apparent (radiographic) ACJ and apparent (radiographic) AC was significantly reduced by varying the beam angulation in either a vertical or horizontal direction. Results for individual tooth types were qualitatively similar but larger discrepancies were found in molars followed by premolars and incisors. The results emphasize the importance of maintaining the ideal X-ray beam, tooth, bone, film relationship when taking radiographs for the assessment of periodontal destruction.
Acrylic Resins↗
Risk estimates for developing motor neurone disease in first-degree relatives.
Patients with motor neurone disease resident in the three counties of South Glamorgan, Mid Glamorgan and Gwent (total population 1,394,400) from 1/11/91 to 31/12/92, were ascertained through general practitioners and neurology department records: 62 out of 71 (51 male, 20 female) index cases ascertained agreed to be visited. These individuals were clinically reviewed, had a detailed family history taken and, after discussion, had a blood sample taken for testing for the X-linked bulbospinal muscular atrophy mutation. The period prevalence of motor neurone disease was 5.02/100,000 with a mean age of onset of 59.4 (S.D. 12.9) years. One 66-year-old male was found to have the X-linked bulbospinal muscular atrophy mutation. A single, definite first-degree relative pair was identified, of whom only one was included in the data. The index cases had a total of 131 offspring and 173 siblings. The risk estimates, by current age, for these first-degree relatives of patients with apparently sporadic motor neurone disease decreased from 1 in 85 at age 20 years to 1 in 1683 at age 80 years. These estimates require confirmation in an independent sample, as they are based on a single "event".
Aged↗
The effect of oxidising mouthrinses compared with chlorhexidine on salivary bacterial counts and plaque regrowth.
For various clinical indications, oxidising agents have been used in dentistry for many years. Little is known, however, of their antibacterial activity and their ability to inhibit plaque formation. In this study, 2 mouthrinses containing peroxyborate (Bocasan) and peroxycarbonate (Kavosan) were compared alongside a negative control saline rinse and a positive control chlorhexidine rinse (Corsodyl) for their ability to inhibit plaque reformation. Employing a randomised four replicate 4 x 4 latin square cross over design and, whilst omitting all other oral hygiene, plaque was measured by area and index after rinsing for 4 days. In a second study, in vivo antibacterial effects of the rinses were assessed by measuring salivary bacterial counts following single rinses with the preparations at various time intervals over 7 h. Plaque inhibition by chlorhexidine was significantly greater than the other rinses. All rinses were significantly better than the saline rinse at inhibiting plaque. For plaque area, the peroxycarbonate rinse was significantly better than the peroxyborate rinse at inhibiting plaque. Salivary bacterial count reductions were significantly greater compared to saline with chlorhexidine at all time intervals up to 7 h. Whilst both peroxyborate and peroxycarbonate rinses produced greater reductions in bacterial counts than saline up to 3 h, at no time interval were the differences significant. The findings of these studies would suggest oxidising mouthrinses may inhibit plaque formation not by a direct antibacterial effect, but by some other mechanism. The magnitude of plaque reductions obtained with the peroxyborate and more so peroxycarbonate rinses would suggest a need for further study of these preparations when used as adjuncts to normal toothbrushing.
Analysis of Variance↗
Comparative staining in vitro and plaque inhibitory properties in vivo of 0.12% and 0.2% chlorhexidine mouthrinses.
The mere incorporation of an active ingredient in an oral hygiene product does not necessarily guarantee efficacy. As new formulations appear, it would seem prudent to at least screen for activity by comparison with an established product. The aim of this study was to compare a new 0.12% chlorhexidine containing rinse with a well researched 0.2% chlorhexidine rinse product. The rinses were firstly compared in vitro for dietary staining effects and in vivo for plaque inhibition. Both formulations in vitro produced progressive staining of acrylic specimens with increasing passages through a standard tea solution. The clinical investigation was a 3-treatment, randomised, double blind, crossover, 4-day plaque regrowth study, balanced for 1st and 2nd order residual effects and involving 24 volunteers. From a zero plaque baseline, volunteers suspended oral hygiene and rinsed 2 x per day with the allocated rinse. The chlorhexidine doses were 18 mg and 20 mg per rinse for the 0.12% and 0.2% formulations, respectively. Plaque was scored by area and index on day 5. The results showed that the 2 chlorhexidine rinses were similar in efficacy by comparison with the control rinse. These studies in vitro and in vivo indicate that the chlorhexidine in the new preparation is available and active and the product could find use in those preventive applications suggested for other chlorhexidine formulations.
Acrylic Resins↗
An approach to efficacy screening of mouthrinses: studies on a group of French products (II). Inhibition of salivary bacteria and plaque in vivo.
The aim of this study was to determine the value of screening studies to assess the efficacy of antiseptic mouthrinse products relative to proven products. The products tested were 6 antiseptic mouthrinses available in France. 4 contained chlorhexidine (Eludril, Hibident, Parodex and Prexidine) with Hibident considered the positive control. 1 product contained cetylpyridinium chloride (Alodont) and 1 hexetidine (Hextril). Saline was used as the negative control. The 1st study assessed the persistence of action of the products by recording salivary bacterial counts before and up to 7 h after single rinses. The 2nd study measured the inhibition of plaque regrowth, from a zero baseline, in the absence of tooth-brushing over a 4-day period. Both studies used blind randomised crossover designs balanced for residual effects. Salivary bacterial count reductions with time were highly significantly greater for Parodex to 5 h and Hibident and Prexidine to 7 h; There were no significant differences between the latter three chlorhexidine rinses except at 3 h, when decrements were significantly less with Parodex. Despite a mean trend in favour, Alodont, Eludril and Hextril were not significantly different from saline. Plaque inhibition by area and index was highly significantly different between products. Hibident, Parodex and Prexidine showed similar plaque inhibition and were significantly more effective than all other rinses. Eludril and Hextril were significantly more effective than saline but Alodont was not. Taken with the associated study in vitro and published reports on the same or similar products, it is apparent that efficacy of a product cannot be assumed merely because it contains a known active plaque inhibitor.(ABSTRACT TRUNCATED AT 250 WORDS)
Anti-Infective Agents, Local↗
Radiographic alveolar bone loss from posterior teeth in young adults over a 4-year period.
The objective of this study was to determine alveolar bone loss from premolar and molar teeth in young adults over a 4-year period between the ages of 15-16 years and 19-20 years. Pairs of posterior bitewing radiographs from 382 subjects aged 15-16 years were examined and the height of the alveolar bone adjacent to mesial and distal tooth surfaces recorded. Repeat radiographs of the same individuals taken 4 years later were then examined and the height of the alveolar bone remeasured. Change in bone height over the study period was computed for individual sites. Clinical data for the cohort were also obtained at both examinations and included plaque score, bleeding on probing and probing depth. Of the 3314 sites, 16.7% exhibited bone gain, 4.5% exhibited no change whilst 78.8% demonstrated bone loss. The overall mean bone loss for all sites combined was 0.407 mm. Bone loss than 0.5 mm was found in 36% of sites, bone loss between 0.5 and 0.99 mm in 33% of sites whilst only 0.5% of sites had bone loss greater than 2 mm. Only one site had bone loss greater than 3 mm. Bone loss was affected significantly by subject (p < 0.001) and by site (p < 0.05) but there was no significant effect for tooth type, whether the surface was mesial or distal or between quadrants. There was significantly more bone loss from around maxillary teeth than mandibular (p < 0.05). There were no significant associations between bone loss and plaque score, bleeding on probing, pocket depth, gender or social class.
Adolescent↗
Residual effect of chlorhexidine gluconate in 4-day plaque regrowth crossover trials, and its implications for study design.
The efficacy of oral hygiene agents in preventing the accumulation of plaque from a zero baseline is conveniently evaluated in the 4-day plaque regrowth model. In many studies a panel of volunteers has been used to compare several agents according to a highly efficient Latin square based crossover design. Often chlorhexidine gluconate is included as a positive control; there is concern that the effect of this potent agent might persist for longer than the 3-day washout period often employed. To test this hypothesis of residual effect, we put together the evidence relating to possible carryover from 12 studies. The residual effect of chlorhexidine differs from that of an inert rinse such as saline or water. Consequently, a longer washout period, such as 10 days, is preferable. Studies omitting chlorhexidine are worth considering. Designs should be balanced for residual effects, at least from the preceding treatment period; several useful designs with this property are presented.
Chlorhexidine↗
Reproducibility of repeat bitewing radiographs determined by measurement of the distance between the amelocemental junction and the alveolar crest: an ex vivo study using human skulls.
OBJECTIVE: To assess the reproducibility of repeat bitewing radiographs. METHODS: Five right and left pairs of posterior bitewing radiographs were taken without the use of beam-aiming or film-holding devices in five dry skulls with complete dentitions. The amelocemental junction (ACJ) and alveolar crest (AC) of every interdental site was traced on projected radiographs and the linear distance between the ACF and AC determined. RESULTS: There was close concordance between the ability to read the ACJ on the approximal tooth surface and the AC. The overall readability of interdental sites was 71% although sites at the extremities of radiographs were often unreadable. Kappa analysis of the readability of alveolar bone height from repeat radiographs was 0.52. There were significant differences in the reproducibility of ACJ and AC measurements from repeated radiographs (p<0.001). Intra-examiner variability was significantly less (p<0.001) than that due to repeat radiography with no significant differences between sites. The standard deviation for all surfaces from repeat readings of the same radiographs was 0.12 mm compared with 0.51 mm from repeat radiography. CONCLUSIONS: In this study a freehand technique produced a degree of imprecision in readings of alveolar bone height from successive films of the same site. In clinical terms, a difference of more than 1.4 mm between pairs of serial measurements from the same site would have to occur in order to be certain that the difference was not measurement error but real bone loss.
Alveolar Bone Loss↗