Halitosis is the term used to define an unpleasant odor emanating from the mouth. Some lung diseases and diabetes are among the extra-oral causes of this condition. However, no studies have evaluated the causes and treatment of halitosis in the population of older adults with denture. A randomized, controlled trial is proposed. The patients will be divided into 2 groups: G1: older adults who wear complete dentures and will be treater with tongue scraper (n = 20); G2 older adults who wear complete dentures and will be treater with PDT (n = 20). If the halitosis persists, the participants will be submitted to hygiene procedures for the mucosa and dentures. The evaluation of halitosis will be repeated. If the halitosis is resolved, the participants will return after one week for an additional evaluation. This protocol will determine the effectiveness of photodynamic therapy regarding the reduction of halitosis in older adults with complete denture.

Methods:

A single-center, randomized, controlled, single-blind clinical trial was designed in accordance with the criteria recommended for interventional trials in the SPIRIT Statement. The project for the proposed study received approval from the Human Research Ethics Committee of Universidade Nove de Julho.

Selection of individuals - characterization of sample - Two groups will be composed of older adults (60 years or older) in treatment at the dental clinic of Universidade Nove de Julho. After verbal and written explanations of the study, those who agree to participate will sign a statement of informed consent approved by the Human Research Ethics Committee of Universidade Nove de Julho. The study will be conducted in compliance with the precepts stipulated in the Declaration of Helsinki (revised in Fortaleza, Brazil, 2013).

Calculation of sample size - Initially an error err=|(x_1 ) ̅-(x_2 ) ̅ | was established, where the mean values of groups G1 and G2 whose variances are σ_1^2e σ_2^2, respectively. The effect size was calculated by:

effect size=err/√(σ_1^2+σ_2^2 ) If the normal distribution hypothesis is rejected, the sample size should be corrected by approximately 5%.

Observing statistical samples from the reference Mota et al., 2016; to estimate the mean values and sample variance we obtain the following sample sizes for each group:

Sample Size Group Group Sample Size G1 18 G2 18

Inclusion criteria - Men and women aged 60 years or older using complete dentures.

Exclusion criteria - Dentate patients and edentulous with no complete denture hypersensitivity to the photosensitizing agent used in PDT, H2S < 112ppb.

Training and calibration of examiner - An examiner (gold standard) will perform training and calibration exercises to maximize the reproducibility of the measurements. For such, 10 individuals with halitosis will be evaluated using the Oral Chroma® device. These individuals will not participate in the main study. The intraclass correlation coefficient (ICC) will be calculated for the determination of intra-examiner agreement (≥ 0.90) with regard to the halitosis readings.

Randomization - The 40 individuals with complete denture will be randomized in two groups: Group A (20 individuals submitted to treatment with a tongue scraper) and Group B (20 individuals submitted to treatment with PDT). Opaque envelopes will be identified with sequential numbers (1 to 40) and will contain pieces of paper with the information of the corresponding experimental group (A or B). Blocked randomization will be performed in blocks of five patients (eight blocks for both treatments; example of a block: AABAB). The envelopes will be sealed and kept in numerical order in a safe place until the time of the treatments. The randomization and preparation of the envelopes will be performed by a researcher who will not otherwise participate in the study. Randomization will be performed using Microsoft Excel, version 2013.

Characterization of the study - The experimental design will consist of two groups: G1- older adults with halitosis (SH2 ≥ 112 ppb) who wear complete dentures and treatment with a tongue scraper (n = 20); G2- older adults with halitosis (SH2 ≥ 112 ppb) who wear complete dentures and treatment with PDT (n = 20). The evaluation of halitosis will be performed at baseline (1st session), after treatment with a tongue scraper or PDT (1st session) and after one week (2nd session)

Inclusion Criteria:

Men and women aged 60 years or older using complete dentures

• • Halitosis positive: ≥ 112 ppbin the gas chromatography test

Exclusion Criteria:

• Dentate patients and edentulous with no complete denture hypersensitivity to the photosensitizing agent used in PDT, H2S < 112ppb