En este estudio se encontró reiteradamente que

An understanding of the interplay between resting saliva pH, stimulated saliva pH and buffering capacity as related to salivary flows is important in understanding the risk associated with acidification of the mouth and demineralisation of teeth.

The main buffering system in saliva is the carbonate/bicarbonate system in stimulated saliva while a less active phosphate buffer system is present in

unstimulated and mucous saliva. The carbonate/bicarbonate concentration in saliva decreases with decreasing salivary flow. Stimulation of saliva flow rates will increase bicarbonate concentration and resultant buffering ability to neutralise mouth

acids.(64) (67)

Testing the buffering capacity of saliva gives an indication of the effectiveness of the saliva in neutralizing acids in the mouth, which may come from the diet, from dental plaque or from internal sources (such as gastric reflux). Unstimulated saliva has very low levels of bicarbonate while stimulated saliva has levels of bicarbonate more than 60 times higher. The GC Saliva Check Buffer test kit is designed to correlate with results obtained by titration techniques as specified in Ericsson’s method (1959). (139)

The simple act of chewing produces stimulated saliva with properties very different to resting saliva. Stimulated saliva has much increased speed and volume aiding

swallowing, flushing the mouth of food debris and micro-organisms, clears glucose from the mouth and produces saliva rich in buffers able to neutralise mouth and plaque acidity encouraging growth of a healthier oral biofilm and environment.

The buffer measuring strips in the commercially produced saliva test kit in this study had a range from 0 to 12, based on the traffic light system with red for ‘Very low’ (0-5), yellow for ‘Low’ (6-9) and green for ‘High” (7-10). This system is easy to understand and ideal for training nurses.

Nurse baseline buffer assessments of participants (n=8) found 3 participants with buffering capacity at or above the normal limit (10), 3 at the low range (6-9) and 3 at the very low range (0-5).

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OHT testing was consistently lower with no participant placed in the normal range, 3 in the low and 6 in the very low range. The OHT pattern of scoring is somewhat reflected by nurse results, albeit with higher scores, with nurse scores either within the same category as OHT assessments or one category above. Only Participant 6 may be an exception as there was a 2 category difference between nurses and OHT results (Normal versus Very Low).

It may be possible that the actual saliva buffering capacity was higher (or lower) than the buffer test strips indicate as 4 volunteers scored the maximum score of 12. Assessing the colour variations within the buffer strips can at time be difficult

requiring a second and often a third arbiter and variations in scoring may also occur due variability in people determining colours.

The poorer the buffering capacity, the greater and steeper is the resultant pH drop after a glucose challenge, the more prolonged saliva remains in the acidic and very acidic zones leading to increased acidification of the mouth and increased risk of oral disease and demineralisation of teeth.(138)

Participant numbers were too low to obtain meaningful statistical results.

Larger numbers of test subjects are needed to assess whether buffer assessments by RACF nurses are of benefit in risk assessment of early dementia patients and can help formulate nurse care plans that emphasize preventive interventions aimed at raising oral pH.

Summary

In summary, saliva testing is useful as a teaching tool for nurses and the saliva test results can be used as another tool to assess risk of oral disease. However, the ultimate determinate of effectiveness of an approach using daily scheduled intensive multi-intervention combination therapies deliverable through nurse care plans, will be a decrease in oral and systemic disease over time and not necessarily an

improvement in saliva test results in those people completely lacking adequate salivary function.

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Plaque Scores

Poor oral hygiene results in growth of an oral biofilm, which over time matures and becomes progressively more aggressive adversely affecting hard and soft dental tissues of the mouth. Mature dental plaque can cause periodontal disease, tooth decay and poor oral and systemic health. In aged care, the inability to maintain one’s own oral health due either to frailty, illness or dementia directly impacts oral and systemic health.

A number of indices have been developed to assess and monitor functional dependency in manipulating aids used in oral self-care such as the Index of the Activities of Daily Oral Hygiene (ADOH)(140) and Activities of Daily Living Oral Health (ADLOH).(35)

A Perth cohort study found mean plaques scores and extent of gingival inflammation were higher for residents classified as having a disability that affected their ability to maintain their own oral care. Residents who needed assistance with brushing had higher mean plaque score and more moderate gingival inflammation. Residents with disability and dementia had significantly worse results.(35)

Assessing the amount of plaque present in the mouth may give an indication of the risk of oral disease, the effectiveness of oral hygiene measures to prevent or control oral diseases and help prevent respiratory infections and systemic disease. (8, 10, 141) A systematic review revealed that root caries incidence can be predicted by risk models and that the most frequently described predictors of root caries incidence in published studies of risk models are root caries prevalence, number of teeth, and plaque index.(7)

Despite a simplified Oral Hygiene Index (OHI-S) being available (142), the longer Greene and Vermillion Oral Hygiene Index (OHI) was chosen for this study.(101, 142, 143)

The OHI was chosen as plaque and calculus scoring was intuitive and any tooth with the greatest coverage of plaque and debris could be chosen in each sextant allowing flexibility in selecting which tooth to score in a sextant due to the increased

prevalence of tooth loss in the elderly. The scoring was rapid and suitable for early dementia participants in this study

The use of compressed air to dry tooth surfaces and water to remove gross debris allows easier and probably more accurate plaque score readings. OHT’s did not have the benefit of compressed air and water during their assessments which

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confounds the estimates of plaque scores between operators.

A further limitation was that Greene and Vermillion plaque scores are taken from buccal and lingual surfaces of teeth without scoring interproximal surfaces.

Interproximal and lingual cleaning of teeth are much more difficult procedures than buccal and lingual surfaces. Cleaning interproximal surfaces may not be performed adequately particularly when assistance is required and resistive behaviours occur. Poorer interproximal cleaning may not be reflected in Greene and Vermillion plaque scores, nor would an association be detected of an increased risk of interproximal caries due to poor interproximal cleaning.

Assisted cleaning of buccal and lingual surfaces by RACF staff is more likely to be adequate on buccal and lingual surfaces. Plaque scores might even decrease after adequate assisted cleaning of buccal and lingual surfaces giving a false sense of improvement in a key oral health index yet the risk of interproximal caries may remain unchanged.

Another limitation of the OHI plaque scoring system is the inability to assess the thickness of dental plaque and oral biofilms and hence the total volume of cannot be assessed. The thickness of plaque will affect how well plaque acid can be

neutralised by the normal flow of saliva and the effectiveness of preventive products and re-mineralising agents to penetrate plaque.

In this study, examiners (one dentist and two OHTs) were not calibrated prior commencement of the study. Future studies will require calibration between all examiners.

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Total Oral Bio-Burden Index (TOBI)

Current plaque scoring systems have a number of limitations. Most plaque scoring systems give an average score for selected teeth in each sextant which when added together give an indication of risk based only on dental plaque on teeth based on surface area not on volume. A further limitation of plaque scoring systems is that they do not assess the total bio-burden on all surfaces in the oral cavity which would include:- soft and hard dental tissues, fixed prosthetic units (implant retained

overdentures or bridge pontics) and dentures.

The Total Oral Bio-burden Index (TOBI) is a new preventive oral health concept developed by the author and is the summation of plaque scores on all surfaces in the oral cavity consisting of:-

 Soft Tissue Bio-burden Score: The total plaque or microbial soft tissue load of the soft tissues of the mouth and tongue from the base of the tongue forward, including soft and hard palate, gingiva and mucosa.

 Dental Bio-burden Score: The total dental plaque score for all teeth and fixed dental units in the mouth including bridge pontics or fixed implant retained overlay dentures. In other words a plaque score is given to any structure in the mouth that cannot be removed.

 Denture Bio-burden Score: Plaque scores given to both tissue fitting surfaces and occlusal surfaces of dentures. The denture bio-burden score is obtained by the addition of tissue fitting and occlusal surface plaque scores.

The Total Oral Bio-Burden Index (TOBI) is proposed a method to establish a score for the total oral bio-burden based on surface area on all surfaces in the mouth. It is suggested that TOBI may better correlate with the over-all risk of oral and systemic disease emanating from the mouth, particularly with respiratory infections.

An assessment of the soft tissue bio-burden was beyond the scope of this study. The author is not aware of a method to assess the biofilm covering oral soft tissue

surfaces needed to obtain a Soft Tissue Bio-burden score and at this stage this assessment is a theoretic concept related to a total oral bio-burden concept.

A study to evaluate a mucosal-plaque index (MPS) has been trialled which used a 1 to 4 scale with: 1 = Normal tissue appearance, 2 = Mild inflammation, 3 = Moderate inflammation, 4 = Severe inflammation.(144) Although, the mucosal scoring was based on the appearance of mucosal inflammation and not on the biofilm, their findings may still be useful in assessing oral health risk.

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In this study, only a Dental Bio-burden Score was assessed. Further studies need to be completed to see if these proposed bio-burden scores are effective in assessing risk.

Although a chemical approach to reduce oral micro-flora is not ideal, it may be the only option where assisted brushing is not effective or possible.

The Soft Tissue Bio-burden Score, used alone or in combination with the Dental and Denture Bio-burden scores, is a theoretical concept that may help explain the

rationale for when to use more intensive chemical anti-microbial interventions containing chlorhexidine and sodium bicarbonate in care plans to reduce total oral pathogenic bio-burden.

Fig 36: Dental Oral Bio-burden Score

Modified from Greene and Vermillion: Average plaque score per sextant multiplied by the number of total fixed dental units in the mouth

Participants 1,2,3,8 with 3,3,6,8 carious lesions respectively

In the Greene and Vermillion Oral Hygiene Index (OHI), plaque scores are totalled and divided by the number of sextants scored. This score is an average score obtained by scoring a tooth in each sextant and does not take into account the total number of retained teeth or fixed dental units that cannot be removed from the mouth. The greater number of teeth retained and the larger the surface area of fixed dental units such as bridge pontics and implant retained prosthesis, the greater will be the overall dental bioburden.

Figure 36 illustrates how a Total Dental Bio-burden Score could have an increased sensitivity as a measurement tool as compared to OHI scoring systems.

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For example, Participant 6 above, has only 5 remaining anterior teeth, wears a full upper denture opposing a 6 teeth part lower chrome denture. Her average sextant plaque score was 2.0. When multiplied by her remaining teeth, Participant 6 has a total dental bio-burden score of 10.0. Her Denture Bio-burden score needs to be added to the dental bio-burden score to give a Total Oral Bio-burden Index result. However, even when dementia patients show resistive behaviours making assisted brushing difficult, dentures can usually be removed, cleaned and disinfected, while natural teeth and fixed dental units cannot.

Participant 5 had 26 remaining teeth, did not wear a denture and had a lower average sextant plaque score of 1.83. When multiplied by the total number of remaining teeth (or fixed dental units), Participant 5 had a Dental Bio-burden Score of 47.7.

Although participant 5 had a lower average plaque score than participant 6

(2.0 versus 1.83 respectively), participant 5 has a greater Total Dental Bio-burden Index (47.7 versus 10 respectively) due to increased number of retained teeth placing her at higher risk of oral and systemic disease sourced from the mouth.

It is suggested therefore that a person with a plaque score of 10, from 6 sextants, but with a full complement of 32 teeth would have a greater dental bio-burden than would another person with the same plaque score of 10 but with 20 remaining teeth in 6 sextants. In the first example, dividing the plaque score of 10 by the 6 sextants scored results in an average plaque score per sextant (10/6=1.7). Multiplying the average plaque score by the total number of teeth in the mouth results in a Total Dental bio-burden of 53 (1.7*32= 53) for a person having 32 teeth.

In the case of the second example, multiplying average plaque score by the total number of teeth results in a Total Dental Bio-burden of 34 (10/6=1.7 * 20 = 34) for the person having 20 teeth.

Having a similar average sextant dental plaque scores may have very different oral risk profiles dependant on the number of teeth retained. The Total Dental Bio-burden Index may better reflect this risk. In the above example, the first person would be at higher risk of oral and possibly respiratory disease than the second with dental bio- burden scores of 53 and 34 respectively despite having the same OHI plaque scores.

Under this scoring system the range of Dental Bio-burden Scores would be between 0 – 192 for 32 teeth.

The concept of assessing risk based on measuring the surface area occupied by pathogenic biofilm on oral soft tissues, fixed dental units and dentures to obtain an oral bio-burden score was not considered as part of the study protocols prior the commencement of this study and only developed as the study progressed. As a

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result, dentures in this study were not plaque scored and the concept of an

assessable denture bio-burden score based on total denture size was not included in this study but may be useful in future oral health studies.

OHAT Limitations with Respect to Bio-Burden

The OHAT section ‘Dentures’ assesses the structural integrity and function of the denture by assessing the denture base, number of fractured or worn teeth and number of hours worn during the day.

Three participants with dentures were assessed through OHAT, by nurses and an OHT at baseline and again at 10 weeks by an OHT using the Montefiore OHAT scoring system:- 1 (healthy), 2 (changes), 3 (unhealthy), 4 (referral) is equivalent to scores 0, 1, 2, 3 in the Chalmers 2009 study.

Table 28 OHAT Denture Scoring System

Participant Nurse baseline OHT baseline OHT +10 weeks

3 2 2 1

5 1 1

6 1 1 1

Participant 8: had recently lost her denture just prior the commencement of the study Participant 5 attended her baseline OHT assessment visit without taking her denture

The OHAT section ‘Oral Cleanliness’ does not attempt to assess dental plaque but comes closest to assessing oral bio-burden by combining both mouth and dentures cleanliness into one assessment.

Montefiore scoring system and descriptors are:

1 scores ‘Clean and no food particles or tartar in mouth or on dentures’

2 scores ‘Food, tartar, plaque 1-2 areas of mouth, or on small area of dentures’. 3 scores ‘Food particles, tartar, plaque most areas of mouth, or on most of dentures’ Participants 1- 8 nurse oral cleanliness scores at baseline and +10 weeks were

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Table 29 OHAT Oral Cleanliness Scoring System

Participant Nurse baseline OHT baseline OHT +10 weeks

1 1 1 1 2 1 1 1 3 2 1 4 1 1 1 5 1 1 2 6 1 1 1 7 1 1 8 1 1

Baseline Participant Nurses OHAT versus OHT OHAT for oral cleanliness and OHT OHAT cleanliness assessment at Baseline versus +10 weeks

The lower the better

Neither the OHAT categories for ‘Dentures’ or Oral Cleanliness’ differentiate the relative risks from bio-burden sourced from the surface areas of a dentures or fixed dental units.

A Denture Bio-burden score would recognise and quantify the relative risk based on denture surface area. The poorer the cleanliness and the greater the surface area of a denture, the greater will be the biofilm colonising denture surface areas and the greater will be the effect on the total dental bio-burden of the mouth.

A number of studies to assess denture plaque have used erythrosine and fluorescein plaque disclosing dyes to score a denture plaque index. The scoring is usually per denture quadrant and is suitable for use in a RACF setting. (145-147)

Full dentures in the studies above were scored according to the percentage plaque coverage of denture surfaces quadrants on both tissue fitting surface and the outer facial surface quadrants as follows:- 0 = no plaque; 1 = light (25%), 2 = moderate plaque (26% to 50%), 3 = heavy plaque (51% to 75%), 4 = very heavy plaque (76% to 100%).(145)

However, a disadvantage of the denture visual scoring index in the studies above is that the plaque on palatal non tissue fitting surface and dentures plaque thickness or volume of plaque on all denture surfaces are not scored.

Additionally, the size of the denture may affect the amount of biofilm retained in the mouth. A poorly maintained 3 tooth partial denture will have less bio-burden than a poorly maintained 6 tooth partial denture. Denture surface area is difficult to

determine clinically, however a possible solution may be to multiply the denture plaque score by the number of teeth in a partial denture. Further studies need to be carried out to see determine if this is a suitable strategy.

It is suggested that the theoretic Soft Tissue Bio-burden Score, together with the assessable Dental Bio-burden Score and assessable Denture Bio-burden Score should be considered together when assessing total oral bio-burden risk in a

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bio-burden indices is that fixed dental units such as teeth, implant retained over dentures and bridge pontics cannot be removed from the mouth while denture bio- burden risk can be more easily reduced as dentures can be removed, regularly cleaned and disinfected.

Participant numbers were too low to obtain meaningful statistical results of plaque indices.

Although not part of this study, the author recommends the periodic use of disclosing solution on dentures prior cleaning by RACF nurses to better visualise dental plaque