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Biomedical subjects

H P Lawrence

Publications and source records attributed to H P Lawrence.

At least 19 recordsLinked to original sources
PubMed2006

Associations between xerostomia and health status indicators in the elderly.

AIMS: This study investigated the associations between xerostomia (dry mouth) (low, moderate and high) with other categorical variables (e.g. demographic and health status indicators). This paper aims to report on the severity of xerostomia in the elderly population and investigate the relationship with other aspects of perceived health. METHOD: Data were obtained from a cross-sectional survey of 225 elderly people from a large multilevel geriatric care centre. The centre consists of three levels of care: an apartment building in which residents live more or less independently, a home for the aged, and a chronic care hospital. Participants in the study were recruited when they attended the dental care facility. Data were collected by means of a personal interview conducted either at the dental care facility or the participant's residence. RESULTS: The mean age was 83 years. Most were females (72%) and almost all (99%) reported one or more chronic medical conditions; 88% had physical disabilities. Xerostomia was recorded on a seven-point scale. Scores were categorised as low, medium or high and the proportions were 49.3%, 30.3% and 20.4% respectively Bivariate analysis showed no association between dry mouth and sex, age, general health change or life satisfaction. However, when the high xerostomia group was separated out and odds ratios calculated they were 2.3 to 4.9 times more likely to experience a negative impact on health than the low group. Xerostomia did not have a significant impact on chewing capacity, morale or stress, although it contributed to the variability of the oral health-related quality of life measures. It was the only variable with a significant effect (OR 2.55) for the Oral Health Impact Profile-14 and displayed a higher odds ratio (2.76) for the Geriatric Oral Health Assessment Index. Self-reported xerostomia in the elderly population can be categorised into a severity scale. Those suffering most from xerostomia are more likely to experience a negative impact on general health. CONCLUSION: The key finding in this study is that xerostomia has a significant and negative impact on the quality of life of elderly individuals, though oral function may be less affected.

Aged↗
PubMed2005

The relationship between mouthrinse matrix metalloproteinases (MMP-1, 8, 13) and albumin levels with the degree of oral mucositis in allogeneic stem cell transplant patients.

Our aim was to examine the relationship between mouthrinse matrix metalloproteinases (MMPs) and whole albumin levels (AL) relative to oral mucositis (OM) in allogeneic stem cell transplant (alloSCT) patients. Mouthrinse vertebrate collagenase levels are positively correlated with connective tissue destruction (CTD) in periodontitis and may also be involved in CTD associated with OM. Increases in salivary AL have been noted prior to OM onset and may serve as a predictive tool for OM and as a positive control in this study. A total of 23 alloSCT patients were visited eight times over 4 weeks following the transplant. OM was scored via a previously validated examiner-based ordinal system. Mouthrinse samples were collected and analyzed for MMP-1, 8, 13 (members of the vertebrate collagenase group) and AL. No significant correlation was found for MMP levels relative to OM scores. AL were positively and significantly associated with OM scores (P<0.001). MMP levels may not be an important factor in OM development and severity; however, mouthrinse AL may serve as a more objective measure of OM development and severity.

Adult↗
PubMed2003

Periapical health and treatment quality assessment of root-filled teeth in two Canadian populations.

AIM: The prevalence of apical periodontitis (AP) and the quality of root fillings and restorations were determined in two Canadian populations differing in avail-ability of endodontists. METHODOLOGY: Radiographs of first-time university patients aged 25-40 years in Toronto and Saskatoon were examined for missing teeth, presence and standard of root fillings, standard of restoration, and AP according to the Periapical Index. Patients with root-filled teeth were invited for clinical examination and interview to inspect the restorations, and to reveal the providers of endodontic treatment and reasons for extractions of missing teeth. Chi-square and independent t-tests interpreted at the 5% significance level were used to examine associations between the prevalence of AP in root-filled teeth and the standard of the root filling, restoration, and providers of treatment. RESULTS: Proportion of patients with root-filled teeth was significantly higher (P < 0.001) in Toronto than in Saskatoon (39 and 26%, respectively). Presence of AP about root-filled teeth (44% in Toronto, 51% in Saskatoon) was significantly associated with poor density (OR = 2.7) short (OR = 2.4) and long (OR = 2.8) root fillings, and with poor radiographic quality of the restoration (OR = 1.7) Prevalence of AP did not differ significantly between teeth treated by generalists and endodontists. CONCLUSIONS: The prevalence of AP in root-filled and untreated teeth was comparable to that reported in previous methodologically compatible studies. The quality of both the root filling and the restoration were found to impact on the periapical health of root-filled teeth, with the impact of the restoration being most critical when the quality of the root filling was adequate.

Adult↗
PubMed2002

Impacted third molars and risk of angle fracture.

The purpose of this study was to assess the influence of the presence, position, and severity of impaction of the mandibular third molars, on the incidence of mandibular angle fractures. A retrospective cohort study was designed for patients presenting to the Division of Oral and Maxillofacial Surgery, Toronto General Hospital (Toronto, Canada), for treatment of mandibular fractures from January 1995 to June 2000. The independent variables in this study were the presence, position and severity of impaction of third molars. The outcome variable was the incidence of mandibular angle fractures. Hospital charts and panoramic radiographs were used to determine and classify these variables. The demographic data included age, sex, mechanism of injury and number of mandibular fractures. The study sample comprised 413 mandibular fractures in 214 patients. The incidence of angle fractures was found to be significantly higher in the male population and was most commonly seen in the third decade of life. Assault remained the most significant aetiological factor. Patients with third molars had thrice the increased risk of angle fractures when compared to patients without (P<0.001). Impaction of third molars significantly increased the incidence of angle fractures (P<0.001). The severity and angulation of third molar impactions were not significantly associated with angle fractures. This study provides evidence that patients with retained impacted third molars are significantly more susceptible to angle fracture than those without. The risk for angle fracture, however, does not seem to be influenced by the severity of impaction.

Adult↗
PubMed2001

Adhesion of glass-ionomer cement sealers to bovine dentin conditioned with intracanal medications.

This in vitro study assessed the adherence of glass-ionomer cement (GIC) root canal sealers to dentin conditioned by three endodontic intracanal medications. Three GIC sealers were used: (i) Ketac-Endo; (ii) KT-308, an experimental GIC sealer; and (iii) ZUT, a combination of KT-308 and a silver-containing zeolite (0.2% by weight). Superficial dentin of 120 bovine incisor crowns was used as a substrate. The dentin was irrigated with 2.6% NaOCI for 30 s and then blotted dry. One of the following conditioning media (n = 30) was maintained in contact with the dentin for 7 days: (i) Ca(OH)2 paste; (ii) chlorhexidine gluconate (CHX) liquid 0.12%; (iii) formocresol (FML) liquid; (iv) distilled water (dH2O) used as control. The GIC sealers were applied to the conditioned dentin, bench set for 90 min, stored in 100% humidity at 37 degrees C for 48 h, then tested to failure for shear bond strength (MPa) in an Instron machine. In the ZUT specimens, the shear bond strength did not differ significantly among those conditioned with Ca(OH)2, CHX, FML, and dH2O. For KT-308, the mean scores were significantly lower (p < 0.05) after conditioning with CHX than with dH2O. For Ketac-Endo, the mean scores were significantly lower after conditioning with Ca(OH)2 and FML than with dH2O (p < 0.05). Furthermore Ketac-Endo demonstrated significantly lower (p < 0.05) shear bond strength than KT-308 or ZUT to the dentin conditioned with Ca(OH)2 or FML. The results suggest that intracanal medications differentially influence the adhesion of various GIC sealers to root canal dentin.

Analysis of Variance↗
PubMed2001

Aural symptoms in temporomandibular disorder patients attending a craniofacial pain unit.

AIMS: To determine (1) the prevalence of aural symptoms in orofacial pain patients and (2) a potential association between temporomandibular disorders (TMD) and aural health, while controlling for covariates known to be associated with TMD or auditory dysfunction. METHODS: In a retrospective study, health questionnaires, medical histories, clinical findings, diagnoses, and treatments were systematically retrieved from the charts of 776 patients. The dates of initial assessment ranged from May 1987 to June 1999. Of the included subjects, 39.7% were female; the median age was 39 years; 16.4% displayed only aural symptoms (otalgia, tinnitus, vertigo, or perceived hearing loss); 26.4% had both TMD and aural symptoms; 17.8% had TMD but no aural complaints; and 39.4% had neither TMD nor aural symptoms. RESULTS: Of the 344 subjects who had TMD, 59.9% complained of aural symptoms, versus 29.2% of the 432 patients without TMD. Of the subjects with otalgia, tinnitus, vertigo, or perceived hearing loss, 67%, 64.1%, 65.2%, and 62.2% had TMD, respectively. Subjects with aural symptoms were significantly more likely to be female; to consider themselves in poor health; to smoke; or to have TMD, orofacial pain, headaches (temporal, occipital, or frontal), neck and shoulder pain, altered vision and sensation, sleep disturbances, loss of appetite, memory loss, or low energy. Clinical findings indicated that pathognomonic signs of TMD were associated with an increased risk of aural complaints in this patient population. A significantly greater negative impact on normal life functions was found in subjects exhibiting aural symptoms versus those who only had TMD complaints. CONCLUSION: These findings indicate that TMD is significantly correlated to aural health, although no cause-and-effect relationship has yet been demonstrated. Aural symptoms were also found to have a measurable impact on the subjects' quality of life.

Adult↗
PubMed2001

The U.S. Surgeon General's report on oral health in America: A Canadian perspective.

This paper provides an overview of last year's U.S. Surgeon General's report on oral health, describes the burden of oral diseases and craniofacial disorders in the United States, and draws parallels with the state of dental health in Canada and in the province of Ontario. It concludes by focusing on the report's recommendations for future action and briefly notes some of the lessons that Canadians can learn from these findings. The goal of this paper is to stimulate further discussion of the issues raised in the report, in an effort to encourage public-private partnerships dedicated to the creation and support of programs to make oral health a more integral component of general health.

Adolescent↗
PubMed2000

Pharmacodynamic effects of ketoprofen on crevicular fluid prostanoids in adult periodontitis.

The reported therapeutic benefits of nonsteroidal anti-inflammatory drugs (NSAIDs) in slowing periodontal disease progression appear intimately linked to the effective inhibition of local prostaglandin synthesis. This randomized, partially double-blind, controlled trial was conducted to evaluate the pharmacodynamic effects of the NSAID, ketoprofen (KTP), on gingival crevicular fluid (GCF) prostanoids. 42 subjects, ages 35-57 years, with moderate to advanced adult periodontitis were recruited and monitored for 22 days. On day 1, subjects were randomized for 1 of 5 treatments: i) 0.5% KTP gel; ii) 1.0% KTP gel; iii) 1.0% KTP alternate gel; iv) 2.0% KTP gel; v) 25 mg KTP capsule (positive control). Subjects applied 1 ml of gel topically to their gingiva or administered one capsule p.o., b.i.d. for 14.5 days. GCF samples were collected from posterior, interproximal sites on days 1 (pre-dosing; 1, 2, 3, 6 h), 8 (pre-dosing; 2 h), 15 (pre-dosing; 2 h) and 22 (post-treatment). GCF levels of prostaglandin E2 (PGE2) and leukotriene B4 (LTB4) were determined using RIA, and expressed in ng/ml and % reduction from baseline (%Effect). Neither a significant difference among groups nor a dose response in % effect for either prostanoid was evident, both overall and among cohorts with elevated baseline mediator levels ([PGE2]>34 ng/ml; [LTB4]>300 ng/ml). When data were combined from all groups, significant (p<0.01) % reductions in GCF PGE2 were noted at 1 and 2 h post-dosing (29% and 24% respectively). In comparing topical versus systemic formulations, all topical formulations were as equipotent as systemic dosing in altering local prostaglandin levels despite lower KTP exposures with gel treatments. These data indicate that both topical and systemic KTP therapies pharmacodynamically reduce GCF PGE2 levels in adult periodontitis subjects, allowing for potential inhibition of disease progression.

Administration, Topical↗
PubMed2000

Antimicrobial substantivity of bovine root dentin exposed to different chlorhexidine delivery vehicles.

Root canal dentin acquires antimicrobial substantivity after exposure to chlorhexidine gluconate (CHX) for 1 wk. Therefore development of a vehicle for delivery of CHX as an intracanal medication is desirable. This in vitro study assessed the efficacy of two CHX delivery vehicles, a controlled-release device and a gel, to affect antimicrobial substantivity of bovine root dentin. Sixty bovine incisor root specimens were prepared with standardized length (10 mm) and canal diameter (3.3 mm), and coated externally with nail polish. Specimens were divided into four equal groups and their canals medicated for 7 days with either: (i) an experimental controlled-release device containing 25% CHX that was immersed in sterile saline; (ii) 2% CHX gel; or (iii) Ca(OH)2 paste. Sterile saline was used as the positive control. After medication, the canals of the specimens were inoculated with Enterococcus faecalis for 21 days. Root canal dentin samples ranging in depth from 0.1 to 0.45 mm were then obtained using sterile round burs of ascending diameter. Each dentin sample was placed in a separate test tube containing Brain Heart Infusion broth and incubated for 24 h. The optical density (OD) of the broth was then measured spectrophotometrically at 540 nm. The positive control showed significantly higher mean OD values (one-way ANOVA and Tukey's Studentized Range Test; p < 0.001) than the three test groups. The CHX controlled-release device group showed significantly lower OD values than the Ca(OH)2 group; however only at dentin depths up to 0.2 mm. In contrast, the CHX gel group consistently showed significantly lower OD values than both the CHX controlled-release device and Ca(OH)2 groups. These results suggest that bovine root canals medicated with 2% CHX gel for 7 days acquire antimicrobial properties for at least 21 days.

Analysis of Variance↗
PubMed2000

Resistance of a novel root canal sealer to bacterial ingress in vitro.

A dentin-bonding root canal sealer (ZUT) has been developed, consisting of an experimental glass ionomer cement (KT-308) and an antimicrobial silver-containing zeolite (0.2% by weight). This in vitro study evaluated the ability of ZUT used with or without gutta-percha, to resist bacterial ingress of Enterococcus faecalis over a period of 90 days. Canals of 80 single-rooted teeth were prepared with apical patency and filled as follows (n = 10): KT-308 alone; KT-308 with a single gutta-percha cone (SCGP); ZUT alone; ZUT with SCGP; AH26 alone; AH26 with SCGP; positive control-no root canal filling; and negative control-no root canal filling, with the apices of this group sealed with C&B Metabond cement. Teeth were coated with nail polish except for the apical 2 mm, and each tooth was sealed in a 4-ml glass vial, with an 18-gauge needle inserted through the vial cover and bonded into the pulp chamber with C&B Metabond cement. After sterilization with 2.5 Mrad gamma-radiation, Brain Heart Infusion broth with phenol red was injected into each vial. An inoculum of E. faecalis was pipetted through the needle into the pulp chamber every 5 days, and the broth was monitored daily for color change and turbidity. When change occurred, the broth was cultured for growth of E. faecalis. Kaplan-Meier survival analysis and the log-rank test revealed no significant differences among the three sealers used. The presence of gutta-percha, however, significantly improved resistance to bacterial ingress through obturated root canals (X, p < 0.05). Under the conditions of this study, the hypothesized advantage of ZUT (0.2% zeolite) was not demonstrated.

Anti-Infective Agents, Local↗
PubMed1999

Efficacy of antifungal agents in tissue conditioners in treating candidiasis.

UNLABELLED: Chronic atrophic candidiasis is prevalent in up to 72% of institutionalized geriatric populations and is causally associated with Candida albicans. Topical antifungal treatments are difficult to implement in some geriatric patients due to cognitive impairment, reduced motor dexterity and memory loss. OBJECTIVE: This in vitro study incorporated antifungal agents into tissue conditioners to investigate the effectiveness of this method of drug delivery. DESIGN: Combinations of nystatin, fluconazole, itraconazole and Coe Soft, Viscogel, Fitt were tested at 1, 3, 5, 7, 9 and 11 wt/wt%, with and without sterilized saliva. 6 mm diameter cores were punched in Sabouraud plates pre-grown with standardized C. albicans. Antifungal agents plus tissue conditioner mixtures were injected into each core. Inhibition diameters were measured for 14 days. RESULTS: Cores with only tissue conditioners acted as negative control and showed no significant inhibition activity (ANOVA, p > 0.05). Peak activity was between 65 to 89 hours; followed by a plateau. Itraconazole had greater fungicidal activity than fluconazole; while nystatin was found to have the least fungicidal activity (ANOVA, p < 0.05). The most effective concentration for nearly all combinations was 5% wt/wt (ANOVA, p < 0.05). Specimens with saliva showed greater antifungal activity than those without (t-test, p < 0.001). Itraconazole altered the physical properties of Viscogel hence this combination is not recommended for clinical use. CONCLUSION: The treatment of chronic atrophic candidiasis by incorporation of antifungal drugs into tissue conditioners is efficacious. 5% wt/wt itraconazole mixed with Coe Soft or Fitt is recommended for clinical study where compliance of patient or care giver cannot be relied upon. Peak antifungal activity at 3 days suggests that mixtures prepared for clinical study may be replaced soon after this time for maximum effectiveness.

Acrylic Resins↗
PubMed1999

Periodontitis and cytokine expression in CD14 deficient patients.

Patients with paroxysmal nocturnal haemoglobinuria (PNH) are deficient in monocytic CD14. The aim of this research was to determine the interrelationships among periodontal disease status, local levels, and monocytic secretion of inflammatory mediators in patients with PNH and matched controls. This study utilised a cross sectional, non-randomised design. PNH patients and matched controls (age, race, gender) were assessed for periodontal status, levels of PGE2 and IL-1beta within the gingival crevicular fluid (GCF), and levels released from lipopolysaccharide (LPS) stimulated peripheral blood monocytes in culture. Results indicate no statistical differences in extent and severity of periodontal disease or GCF mediator levels between the two groups. Monocyte responses to LPS demonstrated significant differences in PGE2 (P = 0.0009) and IL-1beta (P = 0.003) secretion with PNH monocytes secreting significantly less than controls. A significant positive association was found between the monocytic and GCF levels of PGE2 for all subjects (P = 0.003), PNH (P = 0.015), and control (P = 0.049) groups. This study demonstrated that GPI anchor deficient monocytes have reduced expression of inflammatory mediators in vitro.

Adult↗
PubMed1998

Pharmacokinetic and safety evaluations of ketoprofen gels in subjects with adult periodontitis.

This clinical trial used a randomized, partially double-blind, controlled parallel design to evaluate the pharmacokinetics and safety of the NSAID, ketoprofen (KTP), in gel formulations. Forty-two subjects, ages 35 to 57 years, with generalized, moderate to advanced adult periodontitis were recruited and randomized to one of 5 treatments over a 14 1/2-day treatment period: (1) 0.5% KTP gel; (2) 1.0% KTP gel; (3) 1.0% KTP alternate gel; (4) 2.0% KTP gel; and (5) 25 mg KTP capsule (positive control). Plasma samples were obtained on days 1 (pre-dosing, 0.5, 1, 2, 3, 6 hr), 8 (pre-dosing, 2 hr), 15 (pre-dosing, 2 hr), and 22 (7 days post-treatment). Plasma KTP concentrations were determined by means of high-performance liquid chromatography. Significant differences in mean area under the plasma concentration vs. time curve (AUC(0-infinity)) among the groups were detected (p < 0.001), with the 25 mg p.o. capsule exhibiting the largest value (5054 ng-hr/mL), the 2.0% gel exhibiting an intermediate value (2244 ng-hr/mL), the 1.0% gels exhibiting lower but comparable values (1516 for the alternate formulation vs. 1461 ng-hr/mL), and the 0.5% gel showing the lowest value (736 ng-hr/mL). Significant differences in dose- and weight-adjusted maximum plasma concentration (Cmax/dose/kg) were detected overall such that the 25 mg p.o. capsule demonstrated higher values as compared with the 4 gel formulations (p = 0.001). The 5 treatments exhibited similar mean times of maximum plasma concentration (tmax) values ranging from 0.6 to 1 hr. Systemic exposures relative to dose and body weight were lower for the gel formulations than for the capsule. The relative systemic bioavailability of the gels compared with peroral administration ranged from 54% to 69%.

Administration, Oral↗
PubMed1998

Potential pathogenic mechanisms of periodontitis associated pregnancy complications.

During normal pregnancy, maternal hormones and locally acting cytokines play a key role in regulating the onset of labor, cervical ripening, uterine contraction, and delivery. Maternal infections during pregnancy have been demonstrated to perturb this normal cytokine and hormone-regulated gestation, sometimes resulting in preterm labor, preterm premature rupture of membranes, and preterm low birth weight (PLBW), i.e., < 2,500 g and < 37 weeks of gestation. Our research focus has been to determine whether periodontal infections can provide sufficient challenge to the mother to trigger PLBW. New experiments from 48 case-control subjects have measured gingival crevicular fluid (GCF) levels of PGE(2) and IL-1-beta to determine whether mediator levels were related to current pregnancy outcome. In addition, the levels of 4 periodontal pathogens were measured by using microbe-specific DNA probes. Results indicate that GCF-PGE(2) levels are significantly higher in PLBW mothers, as compared with normal birth weight (NBW) controls (131.4 +/- 21.8 vs. 62.6 +/- 10.3 [mean +/- SE ng/mL], respectively, at P = 0.02). Furthermore, within primiparous PLBW mothers, there was a significant inverse association between birth weight (as well as gestational age) and GCF-PGE(2) levels at P = 0.023. These data suggest a dose-response relationship for increasing GCF-PGE(2) as a marker of current periodontal disease activity and decreasing birth weight. Microbial data indicate that 4 organisms associated with mature plaque and progressing periodontitis--bacteroides forsythus, Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans, and Treponema denticola--were detected at higher levels in PLBW mothers, as compared to NBW controls. These data suggest that biochemical measures of maternal periodontal status and oral microbial burden are associated with current PLBW.

Aggregatibacter actinomycetemcomitans↗
PubMed1997

Inhibition of experimental gingivitis in beagle dogs with topical salivary histatins.

Histatins, histidine-rich proteins found within parotid and submandibular secretions, are a novel class of endogenous peptides with antimicrobial properties. This masked, randomized, placebo-controlled preclinical investigation examined the effect of 3 topical histatins on the development of plaque and gingivitis in beagle dogs. 16, female, 1-year-old beagles were brought to optimal gingival health by mechanical scaling and polishing followed by rigorous daily tooth brushing. At the conclusion of this pretreatment period, dogs were randomly divided into 4 groups for the application of test formulations, and were placed on a plaque-promoting diet. Test agents included 3 synthetic salivary histatins (histatin 5, P-113 and P-113D) which were incorporated in hydroxypropyl methylcellulose gel at a concentration of 0.125%, and a placebo, or negative control, which was the gel vehicle alone. Throughout the 10-week treatment period, test formulations (2.0 ml) were applied 2 x daily to all premolar teeth using a Monojet syringe. Plaque formation and gingival inflammation were assessed using the plaque (PI) and gingival (GI) indices on days 0, 7, 14, 21, 28, 42, 56 and 70. Furthermore, bleeding to probing was recorded as a percent of sites (%BOP) and according to the modified sulcus bleeding index (mSBI). Comparisons among groups and between group pairs (active versus placebo) were made with Kruskal-Wallis tests with the average of data over the interval, days 14-42, being the primary focus of the analysis. From baseline to day 7, all groups expressed similar indices. Thereafter, overall significant differences among the groups were noted at day 42 for PI, at days 21, 28, 42 and 70 for GI, and at days 14 and 28 for %BOP (p < 0.05). In particular, beagles treated with P-113 demonstrated significantly lower PI scores at day 42 (p < 0.05), significantly lower GI scores from days 21 through 42 (p < 0.05), and significantly lower %BOP scores at days 14 and 28 (p < 0.05) compared to beagles treated with placebo. Beagles treated with P-113D exhibited significantly lower GI at day 42 compared to the placebo (p < 0.05). For the primary analysis conducted over the midtreatment interval (days 14-42), significant differences were detected for all parameters except mSBI (p < 0.05). Accordingly, significantly lower PI scores were found for P-113, lower GI scores for P-113 and P-113D, and lower %BOP for P-113 and P-113D compared to placebo (p < 0.05). These data indicate that in the beagle model, salivary histatins, P-113 and P-113D, topically applied, can significantly reduce clinical signs of plaque formation and gingival inflammation.

Administration, Topical↗
PubMed1997

Analytic approaches to longitudinal caries data in adults.

The objective of this paper is to consider current methods for analyzing longitudinal caries data in adults. To illustrate these methods, we used data from the Piedmont dental study, a prospective investigation of the oral health of older adults. Longitudinal dental data sets comprise repeated observations of an outcome (often clustered within randomly selected primary sampling units), and a set of covariates for each of many subjects, in whom clustering can occur as a result of measuring teeth, or surfaces, within people. One objective of statistical analysis is to predict the outcome variable as a function of the covariates, while accounting for the correlation among the repeated observations for a given subject and the effect of clustering within subjects, as well as between subjects within primary sampling units, such as communities, schools, hospitals, or other such units. We considered two statistical approaches: generalized estimating equations and survey regression models. We also examined the impact of varying diagnostic criteria for caries estimation between epidemiologists and clinicians. One approach is to perform the usual time(x) exam score minus time0 score analysis for the baseline and final examinations, while an alternative is to analyze trends among interim examinations. Finally, because caries studies in which the onset of the disease is the endpoint face the problem of censoring due to subject attrition and/or tooth loss, we recommend the incidence density (time-to-event) analytic strategy to address this problem. This approach was found to be most suitable for longitudinal studies of older adults since it accounts for the time each surface remains at risk for the event of interest, making use of interim exam data until the moment the subject and/or the tooth are no longer available for examination. We also included a discussion on biases that occur upon application of the usual methods of estimating caries experience in missing teeth and crowns, which often ignore the classification error in the estimation. We propose a method to adjust for misclassification of the M-component of the DMFS index. In the case where one can observe true reversals or remineralization of caries lesions, we recommend an adjustment formula to account for reversals that are most likely due to examiner misclassification. We provide examples to demonstrate the applicability of the methods for covariates subject to outcome misclassification.

Adult↗