2.1

Study design

The data reported in the present study were baseline recordings obtained at the beginning of a prospective longitudinal study conducted on the risk factors associated with root caries incidence in a cohort of independently living older adults. The study protocol was submitted and given full ethical approval by the Clinical Ethics Committee of the Cork Teaching Hospitals (ECM 4 Y 06/12/11). The study was conducted in compliance with the principles of the Declaration of Helsinki and written informed consent was obtained from each participant. Eighty-five of the individuals whose data are included in this report were also subsequently enrolled in a randomised controlled clinical trial comparing restorative materials in the operative treatment of root caries .

2.2

Recruitment

Adults aged over 65 years of age with any of their remaining natural dentition were invited to attend Cork University Dental School and Hospital for a free dental examination. Advertisements were placed in local shopping centres, community centres and the local press over a period of three months. Telephone contact details of the study co-ordinator were provided and patients were allocated appointments provided they were the appropriate age, and confirmed they had some of their natural dentition remaining. All of the patients recruited to the study were independently living older adults. No financial rewards were offered to patients. Recruitment commenced in October 2012 and was completed in November 2013.

2.3

Inclusion and exclusion criteria

The inclusion criteria for entering this study were:

• •

  Aged 65 or over

• •

  Present a minimum of one natural tooth

• •

  Living independently in the community

• •

  Have sufficient cognitive ability to understand consent procedures

The exclusion criteria for this study were:

• •

  Those living in nursing home facilities

• •

  Individuals requiring antibiotic prophylaxis for periodontal probing

2.4

Data collection and oral examination

Each participant was interviewed by a research assistant prior to the dental examination. During this, the research assistant completed a data collection form which recorded age, gender, education level, medical history, fluoride exposure, oral and denture hygiene practices, smoking and alcohol consumption, and diet information. The medical history form used was the standard form used throughout the dental hospital and the remaining questions were selected from the National Survey of Adult Oral Health 2000–2002 General Health Questionnaire . The subject’s health was classified into one of four categories based on a system developed by the American Society of Anaesthesiologists (ASA). In this classification:

• •

  ASA 1 is a normal healthy patient without systemic disease.

• •

  ASA 2 is a patient with mild to moderate systemic disease.

• •

  ASA 3 is a patient with severe systemic disease that limits activity but is not incapacitating.

• •

  ASA 4 is a patient with severe systemic disease that limits activity and is a constant threat to life.

A single trained and calibrated examiner performed a baseline oral exam in a standard dental operatory equipped with a dental light and air-water syringe. Patients were advised to avoid eating, drinking, smoking, chewing gum, tooth brushing, or mouthwashes for one hour prior to their appointment. Saliva was collected over a period of five minutes following one minute of stimulation by having the participant chew a paraffin pellet. Xerostomia was defined as a stimulated saliva flow rate of < 0.7 ml saliva/min.

The CRT ^® Caries Risk Test (Ivoclar-Vivadent, Schaan, Liechtenstein) was used to record the salivary buffer capacity and counts of mutans streptococci (MS) and lactobacilli (LB). The buffer capacity of stimulated saliva was determined using CRT Buffer ^® (Ivoclar-Vivadent). The test field of the buffer strip was wetted entirely with stimulated saliva using a pipette. After 5 min of reaction, a coloured chart provided by the manufacturer was used to record the buffer capacity as low, medium or high. The MS and LB counts per millilitre saliva were recorded using CRT Bacteria ^® (Ivoclar-Vivadent). The agar surfaces were wetted with stimulated saliva and incubated at 37 °C (99 °F) for 48 h. The MS and LB counts were scored in two categories: <10 ⁵ or ≥10 ⁵ CFU/ml saliva.

Plaque scores were recorded at baseline using the mucosal plaque score (MPS) index . A WHO Basic Periodontal Examination (BPE) probe was used to evaluate the periodontal condition, the presence of calculus and loss of attachment. The diagnostic threshold for periodontal disease was any pocket in the patient’s mouth where the black-band of a BPE probe (3.5–5.5 mm) partially or totally disappeared (i.e. BPE code 3 or greater). Denture wearing was recorded at baseline. Teeth were cleaned with an ultrasonic scaler, rubber cup and prophy paste and were washed and dried prior to caries detection. In this study, coronal caries visible into dentine, which had not cavitated but appeared as a definite shadow under the enamel (visual caries), was coded in the same manner as cavitated coronal caries. Decayed, missing and filled teeth (DMFT) were recorded. Root surfaces were anatomically defined as those surfaces apical to the cementoenamel junction (CEJ).

The root caries classification system used was a modification of the International Caries Detection and Assessment System (ICDAS II) as described in Table 1 . Each root surface was assigned two codes. The threshold applied to define a root surface as carious in this study was a Code 2 caries lesion code in combination with a Code 3 caries activity code, indicating a cavitated lesion of at least 0.5 mm depth which offers no resistance to probing with a ball-ended BPE probe. Secondary caries around an existing root surface restoration was scored in the same manner as a primary carious lesion.

2.5

Statistical analyses

Data from case report forms were entered into SPSS (version 22; SPSS, Inc., an IBM Company, Chicago, IL, USA) software. Fifteen participants were re-examined one week after initial exam. Intra-examiner reproducibility at root surface level was measured by the kappa statistic which was 0.95 for root caries detection indicating high rater reliability. DMFT scores were calculated from a maximum of 32 teeth. Decayed and filled root surfaces (RDFS) was calculated by adding the number of decayed and the number of filled root surfaces. A filled root surface which had secondary decay was categorised as a decayed root surface. Root caries index (RCI) was calculated as follows, [(number of decayed root surfaces) + (number of filled root surfaces)]/(total number of sound and decayed exposed root surfaces) × 100 . The data were described in bivariate tables. Normality was assessed by histograms, normal Q–Q plots, skewness values and their standard errors. For normally distributed data or normally distributed transformed data compartisons were made using a tw-sample t -test. Otherwise the non-parametric tests Mann Whitney U or Kruskal-Wallis were performed. P -values less than 0.05 were considered statistically significant.

Univariate and multivariate logistic regression analyses with the proportion of individuals with root caries experience (filled root surfaces or active root caries lesions) as the dependent variable were undertaken. This variable was dichotomized; subjects with RDFS > 0 were given a value of 1, and those with an RDFS = 0 were given a value of 0. The independent variables included were age, gender, final level of education, ASA category, alcohol consumption, smoking, fluoridated water supply, denture wearing, dental attendance, plaque control, tooth brushing frequency, interdental cleaning, periodontal disease, xerostomia, saliva buffering capacity, strep mutans count, lactobacilli count, number of teeth with coronal decay, number of missing teeth, number of teeth with coronal restoration, and number of exposed root surfaces. The continuous variables (number of teeth with coronal decay, number of missing teeth, number of teeth with coronal restorations, and number of exposed root surfaces) were dichotomized using the last quartile of the frequency distribution of that variable as the cut-off point. This reduced the continuous variables (which were recorded as a numerical value) into categorical variables to facilitate entry into the regression analyses.

The final model was chosen based on the backward elimination process, starting with the full independent variables, followed by subsequent removing of nonsignificant individual independent variables until no other nonsignificant independent variable could be removed.

2.1

Study design

The data reported in the present study were baseline recordings obtained at the beginning of a prospective longitudinal study conducted on the risk factors associated with root caries incidence in a cohort of independently living older adults. The study protocol was submitted and given full ethical approval by the Clinical Ethics Committee of the Cork Teaching Hospitals (ECM 4 Y 06/12/11). The study was conducted in compliance with the principles of the Declaration of Helsinki and written informed consent was obtained from each participant. Eighty-five of the individuals whose data are included in this report were also subsequently enrolled in a randomised controlled clinical trial comparing restorative materials in the operative treatment of root caries .

2.2

Recruitment

Adults aged over 65 years of age with any of their remaining natural dentition were invited to attend Cork University Dental School and Hospital for a free dental examination. Advertisements were placed in local shopping centres, community centres and the local press over a period of three months. Telephone contact details of the study co-ordinator were provided and patients were allocated appointments provided they were the appropriate age, and confirmed they had some of their natural dentition remaining. All of the patients recruited to the study were independently living older adults. No financial rewards were offered to patients. Recruitment commenced in October 2012 and was completed in November 2013.

2.3

Inclusion and exclusion criteria

The inclusion criteria for entering this study were:

• •

  Aged 65 or over

• •

  Present a minimum of one natural tooth

• •

  Living independently in the community

• •

  Have sufficient cognitive ability to understand consent procedures

The exclusion criteria for this study were:

• •

  Those living in nursing home facilities

• •

  Individuals requiring antibiotic prophylaxis for periodontal probing

2.4

Data collection and oral examination

Each participant was interviewed by a research assistant prior to the dental examination. During this, the research assistant completed a data collection form which recorded age, gender, education level, medical history, fluoride exposure, oral and denture hygiene practices, smoking and alcohol consumption, and diet information. The medical history form used was the standard form used throughout the dental hospital and the remaining questions were selected from the National Survey of Adult Oral Health 2000–2002 General Health Questionnaire . The subject’s health was classified into one of four categories based on a system developed by the American Society of Anaesthesiologists (ASA). In this classification:

• •

  ASA 1 is a normal healthy patient without systemic disease.

• •

  ASA 2 is a patient with mild to moderate systemic disease.

• •

  ASA 3 is a patient with severe systemic disease that limits activity but is not incapacitating.

• •

  ASA 4 is a patient with severe systemic disease that limits activity and is a constant threat to life.

A single trained and calibrated examiner performed a baseline oral exam in a standard dental operatory equipped with a dental light and air-water syringe. Patients were advised to avoid eating, drinking, smoking, chewing gum, tooth brushing, or mouthwashes for one hour prior to their appointment. Saliva was collected over a period of five minutes following one minute of stimulation by having the participant chew a paraffin pellet. Xerostomia was defined as a stimulated saliva flow rate of < 0.7 ml saliva/min.

The CRT ^® Caries Risk Test (Ivoclar-Vivadent, Schaan, Liechtenstein) was used to record the salivary buffer capacity and counts of mutans streptococci (MS) and lactobacilli (LB). The buffer capacity of stimulated saliva was determined using CRT Buffer ^® (Ivoclar-Vivadent). The test field of the buffer strip was wetted entirely with stimulated saliva using a pipette. After 5 min of reaction, a coloured chart provided by the manufacturer was used to record the buffer capacity as low, medium or high. The MS and LB counts per millilitre saliva were recorded using CRT Bacteria ^® (Ivoclar-Vivadent). The agar surfaces were wetted with stimulated saliva and incubated at 37 °C (99 °F) for 48 h. The MS and LB counts were scored in two categories: <10 ⁵ or ≥10 ⁵ CFU/ml saliva.

Plaque scores were recorded at baseline using the mucosal plaque score (MPS) index . A WHO Basic Periodontal Examination (BPE) probe was used to evaluate the periodontal condition, the presence of calculus and loss of attachment. The diagnostic threshold for periodontal disease was any pocket in the patient’s mouth where the black-band of a BPE probe (3.5–5.5 mm) partially or totally disappeared (i.e. BPE code 3 or greater). Denture wearing was recorded at baseline. Teeth were cleaned with an ultrasonic scaler, rubber cup and prophy paste and were washed and dried prior to caries detection. In this study, coronal caries visible into dentine, which had not cavitated but appeared as a definite shadow under the enamel (visual caries), was coded in the same manner as cavitated coronal caries. Decayed, missing and filled teeth (DMFT) were recorded. Root surfaces were anatomically defined as those surfaces apical to the cementoenamel junction (CEJ).

The root caries classification system used was a modification of the International Caries Detection and Assessment System (ICDAS II) as described in Table 1 . Each root surface was assigned two codes. The threshold applied to define a root surface as carious in this study was a Code 2 caries lesion code in combination with a Code 3 caries activity code, indicating a cavitated lesion of at least 0.5 mm depth which offers no resistance to probing with a ball-ended BPE probe. Secondary caries around an existing root surface restoration was scored in the same manner as a primary carious lesion.

2.5

Statistical analyses

Data from case report forms were entered into SPSS (version 22; SPSS, Inc., an IBM Company, Chicago, IL, USA) software. Fifteen participants were re-examined one week after initial exam. Intra-examiner reproducibility at root surface level was measured by the kappa statistic which was 0.95 for root caries detection indicating high rater reliability. DMFT scores were calculated from a maximum of 32 teeth. Decayed and filled root surfaces (RDFS) was calculated by adding the number of decayed and the number of filled root surfaces. A filled root surface which had secondary decay was categorised as a decayed root surface. Root caries index (RCI) was calculated as follows, [(number of decayed root surfaces) + (number of filled root surfaces)]/(total number of sound and decayed exposed root surfaces) × 100 . The data were described in bivariate tables. Normality was assessed by histograms, normal Q–Q plots, skewness values and their standard errors. For normally distributed data or normally distributed transformed data compartisons were made using a tw-sample t -test. Otherwise the non-parametric tests Mann Whitney U or Kruskal-Wallis were performed. P -values less than 0.05 were considered statistically significant.

Univariate and multivariate logistic regression analyses with the proportion of individuals with root caries experience (filled root surfaces or active root caries lesions) as the dependent variable were undertaken. This variable was dichotomized; subjects with RDFS > 0 were given a value of 1, and those with an RDFS = 0 were given a value of 0. The independent variables included were age, gender, final level of education, ASA category, alcohol consumption, smoking, fluoridated water supply, denture wearing, dental attendance, plaque control, tooth brushing frequency, interdental cleaning, periodontal disease, xerostomia, saliva buffering capacity, strep mutans count, lactobacilli count, number of teeth with coronal decay, number of missing teeth, number of teeth with coronal restoration, and number of exposed root surfaces. The continuous variables (number of teeth with coronal decay, number of missing teeth, number of teeth with coronal restorations, and number of exposed root surfaces) were dichotomized using the last quartile of the frequency distribution of that variable as the cut-off point. This reduced the continuous variables (which were recorded as a numerical value) into categorical variables to facilitate entry into the regression analyses.

The final model was chosen based on the backward elimination process, starting with the full independent variables, followed by subsequent removing of nonsignificant individual independent variables until no other nonsignificant independent variable could be removed.