Oral Health Status in Older People with Dementia: A Case-Control Study

Round 1

Reviewer 1 Report

The topic of the manuscript is the association between cognitive impairment and tooth loss which are essential problems in ageing populations.

The abstract and the main text of the article are informative. The Introduction clearly presents the current problems of dementia and tooth loss. The section "Material and Methods" briefly explains the chosen study design. However, the incorrect statistical tests have likely been conducted (the detailed comments below). Therefore, the section "Results" must be improved with new proper statistical analyses. The Discussion is well written, meanwhile, the separate section "Conclusions" should be considered.

Some following points must be clarified/corrected for the further processing of this article.

Merits-related comments:

1. The title should be more informative for readers.
2. In the keywords, instead of “bleeding index”, it is suggested “oral health”.
3. It is not understandable why the control group is more numerous than the study group (especially since the age- and gender-matching was declared).
4. In inclusion criteria probably should be written “… able to participate in the study (saliva sampling, oral examination)” against “… able to participate in the study; saliva sampling; oral exploration”, however, there is no information on the laboratory analysis of saliva in the article.
5. Please justify the division into intervals: 1-9, 10-19, 20-32 teeth.
6. In "Material and Methods" the halitosis score should be wider described (scored 0-10, but in the study group the highest value is 6), as well as plaque index according to Silness and Löe. Moreover, the term “bacterial plaque” should be replaced by “plaque index” and this parameter should be ranged between 0-3. Therefore, it is incomprehensible why there are surprisingly high values in the tables.
7. In the tables for binary qualitative variables (such as cardiovascular disease, etc.) there is no need to present percentages for both categories - enough for one of them (“yes” or “no”). Also, the columns named “Test” are needless.
8. In the case of continuous variables (such as age, BMI, etc.), compliance with the normal distribution must be checked, e.g. by Shapiro-Wilk test. The compared variables probably do not have a normal distribution, and then non-parametric tests should be used instead of parametric ones. Furthermore, they should be presented as medians and quartiles (not means and standard deviations).
9. In cooperation with the statistics, it is worth considering constructing a multivariate regression model for the relationship between oral health and cognitive impairment. It will allow identifying the main factors associated with the oral cavity condition, which are predictive of dementia.
10. The section "Conclusions" is not mandatory but can be added to summarise the manuscript with the apparent “take-home” messages from the Discussion.
11. It is suggested to add more recent articles from 2019-2020 to the references in the Discussion.

Technical comments:

1. The manuscript should be prepared using the Microsoft Word template (https://www.mdpi.com/files/word-templates/jcm-template.dot).
2. The abstract should be a single paragraph and follow the style of structured abstracts but without headings.
3. All Tables should be inserted into the main text close to their first citation and appropriately formatted.
4. The explanation for bold p-values should be added under the Tables.
5. In the text, reference numbers should be placed in square brackets [ ].
6. The citation list must be corrected. References should be described as follows:
   1. Author 1, A.B.; Author 2, C.D. Title of the article. Abbreviated Journal Name Year, Volume, page range.
7. In Author Contributions the following statements should be used "Conceptualization, X.X. and Y.Y.; Methodology, X.X.; Software, X.X.; Validation, X.X., Y.Y. and Z.Z.; Formal Analysis, X.X.; Investigation, X.X.; Resources, X.X.; Data Curation, X.X.; Writing – Original Draft Preparation, X.X.; Writing – Review & Editing, X.X.; Visualization, X.X.; Supervision, X.X.; Project Administration, X.X.; Funding Acquisition, Y.Y.”, and all co-authors must be included.

Author Response

The topic of the manuscript is the association between cognitive impairment and tooth loss which are essential problems in ageing populations.

 

We revised the manuscript according to the reviewers’ comments. Thank you very much for your kind consideration

 

Some following points must be clarified/corrected for the further processing of this article.

Thank you very much for your comments. We tried to revise manuscript according to your suggestions. It is a hope that this effort satisfies your concern

• The title should be more informative for readers. It has been modified
• In the keywords, instead of “bleeding index”, it is suggested “oral health”. OK
• In inclusion criteria probably should be written “… able to participate in the study (saliva sampling, oral examination)” against “… able to participate in the study; saliva sampling; oral exploration”, however, there is no information on the laboratory analysis of saliva in the article.  We agree with Reviewer  on this point
• Please justify the division into intervals: 1-9, 10-19, 20-32 teeth.:  Following the proposed criteria Takiguchi T, Yoshihara A, Takano N, Miyazaki H. Oral health and depression in older Japanese people. Gerodontology. 2016 Dec;33(4):439-446
• In "Material and Methods" the halitosis score should be wider described (scored 0-10, but in the study group the highest value is 6), There was no score higher than 6

 

• Moreover, the term “bacterial plaque” should be replaced by “plaque index” and this parameter should be ranged between 0-3. Therefore, it is incomprehensible why there are surprisingly high values in the tables.  We agree. We tried to clarify the section pertinent to the study design. Index  according to  the O’Leary
• .The oral hygiene status was evaluated according to the O’Leary plaque control record. After staining for dental plaque, the presence of dental plaque on each of the four surfaces (mesial, distal, buccal, and lingual or palatal) was recorded for each remaining tooth. The percentage of plaque-positive surfaces was calculated.

In the tables for binary qualitative variables (such as cardiovascular disease, etc.) there is no need to present percentages for both categories - enough for one of them (“yes” or “no”). Also, the columns named “Test” are needless. OK  We agree

In the case of continuous variables (such as age, BMI, etc.), compliance with the normal distribution must be checked, e.g. by Shapiro-Wilk test. The compared variables probably do not have a normal distribution, and then non-parametric tests should be used instead of parametric ones. Furthermore, they should be presented as medians and quartiles (not means and standard deviations).  We agree

	Kolmogorov-Smirnov
	stadistic	p-value
Age	.059	.149
BMI	.063	.200
Pocket depth	.077	.200
Index plaque	.075	.200
Bleeding upon probing	.078	.200
No. teeth in mouth	.092	.088

 

In cooperation with the statistics, it is worth considering constructing a multivariate regression model for the relationship between oral health and cognitive impairment. It will allow identifying the main factors associated with the oral cavity condition, which are predictive of dementia. We agree. We tried to clarify the section pertinent

.The section "Conclusions" is not mandatory but can be added to summarise the manuscript with the apparent “take-home” messages from the Discussion.

It is suggested to add more recent articles from 2019-2020 to the references in the Discussion.

Thank you very much for pointing this issue. We discussed this matter in our discussion section

• Thomson WM, Barak Y. Tooth Loss and Dementia: A Critical Examination. J Dent Res. 2020 Sep 18:22034520957233.
• Tsai YC, Wang HJ, Wang LY, Shaw CK, Lee YP, Lin MC, Huang CH. Retrospective analysis of the association between tooth loss and dementia: a population-based matched case-control study. Community Dent Health. 2020 27;37(1):59-64.
• Kang J, Wu B, Bunce D, Ide M, Pavitt S, Wu J. Cognitive function and oral health among ageing adults. Community Dent Oral Epidemiol. 2019 ;47:259-266

 

Technical comments:

• The manuscript should be prepared using the Microsoft Word template (https://www.mdpi.com/files/word-templates/jcm-template.dot).
• The abstract should be a single paragraph and follow the style of structured abstracts but without headings. Has been changed  
• All Tables should be inserted into the main text close to their first citation and appropriately formatted. The explanation for bold p-values should be added under the Tables. We agree
• In the text, reference numbers should be placed in square brackets [ ].OK
• The citation list must be corrected. References should be described as follows:OK
• Author 1, A.B.; Author 2, C.D. Title of the article. Abbreviated Journal Name Year, Volume, page range. Ok
• In Author Contributions the following statements should be used  Has been added

Reviewer 2 Report

The study undertakes two important fields of dentistry - gerodentistry and oral medicine. But the manuscript has to be improved by:

1. adding more information about pathomechanism of dementia in brain tissues and its causes.
2. explanation if this type of changes can appear in oral cavity tissues?
3. explanation why patients with dementia have higher dental plaque scores if  the toohbrushing frequency is higher than in control group?
4. adding conclusions
5. adding limitation of the study - so many diseases where reported by patients and controls - there is no their impact on oral health?

 

Author Response

• Response: Thank you very much for your kind consideration. We tried to revise manuscript according to your suggestions. We hope that this effort satisfies your concern.
• The study undertakes two important fields of dentistry - gerodentistry and oral medicine. But the manuscript has to be improved by: adding more information about pathomechanism of dementia in brain tissues and its causes. explanation if this type of changes can appear in oral cavity tissues? We have added this point to the manuscript.
• Response: We agree. We clarified this matter in the manuscript. explanation why patients with dementia have higher dental plaque scores if  the toohbrushing frequency is higher than in control group?   Dental brushing is probably more deficient in patients with dementia Gil-Montoya JA, Sánchez-Lara I, Carnero-Pardo C et al . Oral hygiene in the elderly with different degrees of cognitive impairment and dementia. J Am Geriatr Soc 2017; 65:642–647.
• .adding conclusions OK
• adding limitation of the study - so many diseases where reported by patients and controls - there is no their impact on oral health? Response: Thank you very much for your kind consideration. We tried to revise manuscript according to your suggestions. We hope that this effort satisfies your concern.
• The study undertakes two important fields of dentistry - gerodentistry and oral medicine. But the manuscript has to be improved by: adding more information about pathomechanism of dementia in brain tissues and its causes. explanation if this type of changes can appear in oral cavity tissues? We have added this point to the manuscript.
• Response: We agree. We clarified this matter in the manuscript. explanation why patients with dementia have higher dental plaque scores if  the toohbrushing frequency is higher than in control group?   Dental brushing is probably more deficient in patients with dementia Gil-Montoya JA, Sánchez-Lara I, Carnero-Pardo C et al . Oral hygiene in the elderly with different degrees of cognitive impairment and dementia. J Am Geriatr Soc 2017; 65:642–647.
• .adding conclusions OK
• adding limitation of the study - so many diseases where reported by patients and controls - there is no their impact on oral health? We agree with Reviewer  on this point

 Thomson and Barack suggested that the possible related mechanisms between tooth loss and cognitive decline in older people are: 1) Tooth loss can compromise nutritional status and this can lead to a weakened nervous system. 2) Tooth loss results in less "interoclusal contacts" , therefore, less somatosensory feedback, leading to a cognitive decline and 3) Chronic periodontitis drives to tooth loss and during this inflammatory process, CNS can be affected, as so can cognition.

Round 2

Reviewer 1 Report

The manuscript has been partially improved according to recommendations.

The authors have corrected the title, the abstract, keywords and all tables. Hygiene indicators and statistical methods have been revised in the methodology. However, the authors did not explain the disproportion in the size of the groups. The halitosis score has not been wider described. The reference of Takiguchi et al. justifying the division into intervals: 1-9, 10-19, 20-32 teeth, should be mentioned in “Material and Methods”. Also, multivariate regression modelling has not been considered. New references from 2019 and 2020, as well as conclusions, have been added.

Unfortunately, most technical comments have not been taken into account: lack of JCM template, tables not in the main text, citation list not formatted according to MDPI style. Reference numbers have been placed in square brackets but sloppily (missing dots or brackets, extra dots or spaces).

Author Response

We revised the manuscript according to the reviewers’ comments. Thank you very much for your kind consideration It is a hope that this effort satisfies your concern.

 

• This is a case control study that identifies people with a particular disease (Dementia) and compares it with the control group that does not suffer that disease which is much more commune. Most of the studies show this same design and follow this same structure.
• . The halitosis score has not been wider described The organoleptic assessment of halitosis was performed using the 10-point organoleptic scale 0: no detectable odour 10: extremely strong odour . Mouth odour (smelled at 10 cm form the oral cavity: while the patient normally breaths and while the patient counts loudly to 10);
• The reference . justifying the division into intervals: 1-9, 10-19, 20-32 teeth, should be mentioned in “Material and Methods has been added
• Multivariate regression modelling has not been considered   In accordance to reviewers indications the following text was added in the manuscript
• Technical errors have been checked. I'm very sorry I don't use template

 

We revised the manuscript according to the reviewers’ comments. Thank you very much for your kind consideration It is a hope that this effort satisfies your concern.

 

• This is a case control study that identifies people with a particular disease (Dementia) and compares it with the control group that does not suffer that disease which is much more commune. Most of the studies show this same design and follow this same structure.
• . The halitosis score has not been wider described The organoleptic assessment of halitosis was performed using the 10-point organoleptic scale 0: no detectable odour 10: extremely strong odour . Mouth odour (smelled at 10 cm form the oral cavity: while the patient normally breaths and while the patient counts loudly to 10);
• The reference . justifying the division into intervals: 1-9, 10-19, 20-32 teeth, should be mentioned in “Material and Methods has been added
• Multivariate regression modelling has not been considered   In accordance to reviewers indications the following text was added in the manuscript
• Technical errors have been checked. I'm very sorry I don't use template

 

We revised the manuscript according to the reviewers’ comments. Thank you very much for your kind consideration It is a hope that this effort satisfies your concern.

 

• This is a case control study that identifies people with a particular disease (Dementia) and compares it with the control group that does not suffer that disease which is much more commune. Most of the studies show this same design and follow this same structure.
• . The halitosis score has not been wider described The organoleptic assessment of halitosis was performed using the 10-point organoleptic scale 0: no detectable odour 10: extremely strong odour . Mouth odour (smelled at 10 cm form the oral cavity: while the patient normally breaths and while the patient counts loudly to 10);
• The reference . justifying the division into intervals: 1-9, 10-19, 20-32 teeth, should be mentioned in “Material and Methods has been added
• Multivariate regression modelling has not been considered   In accordance to reviewers indications the following text was added in the manuscript
• Technical errors have been checked. I'm very sorry I don't use template