Variation in Salivary pH and Dental Caries in Children with and without Cleft Lip and Palate Before and After ToothbrushingABSTRACT
Objective: To assess the relationship between salivary pH variation - measured before and after toothbrushing - and the presence of dental caries in children aged 0-12 years with and without cleft lip and palate (CL/P) in Lima, Peru.
Material and Methods: This analytical and longitudinal study included 104 children, of whom 65 had CL/P and 39 did not. Salivary pH was measured using MQuant® pH-indicator strips, before and after oral hygiene with a fluoridated toothbrush and toothpaste Dentito®. Additionally, the Decayed, Missing, and Filled Permanent (DMFT) Teeth/decayed, extracted, and filled primary teeth index (dmft) was determined through an odontogram.
Results: Significant differences in preand post-brushing salivary pH were observed in both groups (p < 0.001), with greater variation among children with CL/P. However, no significant relationship was found between salivary pH variation and the presence of dental caries in either the CL/P group (p=0.718) or the non-CL/P group (p=0.726).
Conclusion: Children with cleft lip and palate exhibited a significantly greater variation in salivary pH before and after toothbrushing compared with children without cleft lip and palate; this variation was not found to be associated with the presence of dental caries.
Keywords:
Jaw Abnormalities; Cleft Palate; Dental Caries; Saliva.
Introduction
Cleft lip and palate (CL/P) is one of the most common craniofacial malformations worldwide. It affects multiple facial structures, including the alveolar ridge, palate, nose, and ears. This condition can lead to several functional and health complications, including inadequate lip seal, mouth breathing, dental caries, enamel hypoplasia, molar-incisor hypomineralization, and periodontal disease. CL/P is characterized by either partial or complete structural fusion failures between the lip and the palate during the embryonic stage [1].
Saliva is a unique fluid with the potential to become the diagnostic sample of choice, driven by advances in detection technologies and the presence of clinically relevant biomolecules [1]. Such biomolecules contribute to several essential functions, including lubrication, antimicrobial properties, sugar and acid dilution, remineralization, and buffering capacity, which plays a crucial role in maintaining acid-base balance - specifically, salivary pH - which is essential for regulating acidic and alkaline byproducts of bacteria in the biofilm [2-6]. The biofilm can alter the pH balance of the oral cavity. Acidic byproducts lower the pH and contribute to the dental demineralization characteristic of dental caries. In this context, salivary pH measurement can serve as an important biomarker for monitoring and potentially altering the progression of dental caries [6].
Rapidly progressing dental caries are common in children and can lead to the destruction of dentition [7]. Early childhood caries is a condition that significantly affects children up to approximately 5 years of age, compromising their quality of life and causing infection, swelling, pain, and other symptoms [8,9].
Children with CL/P have a reduced ability to remineralize dental enamel due to a lower capacity to neutralize acids, which is suggested to result from alterations in their salivary glands [3]. Additionally, studies indicate children with CL/P tend to have lower, more acidic salivary pH levels [10]. Furthermore, research has found that those who used a presurgical device exhibited higher levels of Streptococcus mutans and Lactobacillus, along with acidic salivary pH, increasing their risk of dental caries [11]. Individuals with CL/P exhibit alterations in the normal oral microbiota, dental eruption, and tooth structure, leading to challenges in oral hygiene and contributing to a higher incidence of dental caries [12,13].
In lowand middle-income countries such as Peru, genetic, environmental, and nutritional factors shape health outcomes in specific ways, making locally generated evidence essential. In oral health, despite abundant international literature on children with CL/P and the high prevalence of childhood caries in Peru, there are no up-to-date data linking variation in salivary pH with the presence of this disease. This gap limits understanding of underlying mechanisms and underscores the need for research to guide preventive and therapeutic strategies tailored to the local context [14-18].
Therefore, the aim of the current study is to determine the relationship between salivary pH variation measured before and after toothbrushing and the presence of dental caries in children with and without CL/P in Lima, Peru. The null hypothesis was: “There is no statistically significant relationship between salivary pH variation, measured before and after toothbrushing, and the presence of dental caries in children in Lima, Peru, either among those with CL/P or those without it.”
Material and Methods
Study Design and Ethical Clearance
The present analytical, relational, longitudinal study was approved by the Ethics Committee of the Faculty of Dentistry, Universidad Nacional Federico Villarreal (UNFV), Lima, Peru (Act No. 3288-2024, May 2024). The study was conducted in accordance with the ethical principles outlined in the Declaration of Helsinki for research involving human subjects. Written informed consent was obtained from the parents or legal guardians of all participating children before enrollment in the study.
Participants
Sampling followed a nonprobability convenience design, with participants selected from clinical visits at the Department of Pediatric Dentistry. The sample comprised 104 children aged 0-12 years - 65 with CL/P and 39 without - who underwent general evaluation at the Pediatric Dentistry service of a Peruvian nongovernmental organization. Owing to wide age variability and limited representation in certain age groups, stratification by age group was not considered methodologically appropriate, as it would not have adequately represented the study population.
Data Collection
Participants were instructed not to eat, drink, or brush their teeth for at least 1 hour before the dental examination. For children older than 3 years, unstimulated whole saliva was collected by asking them to spit into a 15 mL disposable cup, both before and after toothbrushing for 2 minutes with fluoridated toothpaste (1100 ppm F; Dentito®, Intradevco Industrial S.A., Lima, Peru). For children younger than 3 years, saliva was collected using disposable 1 mL syringes.
Unstimulated whole saliva was collected from each participant, and salivary pH was measured 60 seconds after collection, both before and after toothbrushing. Salivary pH was assessed using MQuant® pH-indicator strips (pH 0-14, four-color scale; Merck KGaA, Darmstadt, Germany). Test strips were immersed in the saliva sample for 15 seconds, following the manufacturer’s instructions. The color change was compared with the manufacturer’s reference chart. Salivary pH values were recorded on the data collection form and independently verified by two research authors to ensure accuracy [19].
All teeth of each child were clinically examined for dental caries, and the findings were recorded using the DMFT/dmft index. An odontogram was completed in accordance with the Peruvian Ministry of Health guidelines. Data was tabulated, and scores were assigned to each child. The clinical examinations and scoring were performed by the principal research author, who is duly qualified to apply the DMFT/dmft index for caries detection.
The data collection form included the study variables: salivary pH variation, measured before and after toothbrushing with fluoridated toothpaste, and dental caries, assessed using the DMFT/dmft index.
Data Analysis
As data followed a non-normal distribution, non-parametric statistics were used. The Mann-Whitney U test compared salivary pH variation and DMFT/dmft scores between children with and without CL/P. Spearman's rank correlation assessed the relationship between pH variation and dental caries. All analyses were performed using SPSS v.28 (IBM Corp., Armonk, NY, USA) with a significance level of p < 0.05.
Results
Table 1 and Figure 1 present the descriptive statistics of salivary pH variation in children aged 0 to 12 years, comparing those with and without CL/P before and after toothbrushing. The mean pH variation in children with CL/P (0.82) was significantly higher than that in children without CL/P (0.38) (Mann-Whitney U test, p = 0.001).
Mean, median, and standard deviation of salivary pH variation (preand post-toothbrushing) in children with and without CL/P.
Table 2 and Figure 2 show the mean DMFT/dmft scores for children with and without CL/P. The mean score for the CL/P group was 8.00, compared to 2.49 in the non-CL/P group, with a statistically significant difference between the groups (p < 0.001).
Descriptive statistics comparison of the DMFT/dmft index between children with and without CL/P.
Figure 3 shows the scatter plot of salivary pH variation versus the DMFT/dmft index in children with CL/P. Spearman’s rank correlation indicated no statistically significant association between these variables in either the CL/P group (p = 0.718) or the non-CL/P group (p = 0.726).
Discussion
Research indicates that children with CL/P experience more severe oral health problems than their healthy peers, including higher rates of dental caries, poorer oral hygiene, and ear infections, as well as differences in the oral microbiota between those with and without CL/P [20].
Saliva contains multiple components and physicochemical properties essential for maintaining oral health. In this study, toothbrushing was performed with fluoridated toothpaste because fluoride’s primary mechanism is to enhance enamel remineralization and slow demineralization by attracting calcium and phosphate ions from saliva. Fluoride also interferes with S. mutans metabolism by restricting carbohydrate transport and storage and by reducing extracellular polysaccharide production through its interaction with the enolase enzyme [21].
We evaluated salivary pH variation in children aged 0-12 years with CL/P before and after oral hygiene with a toothbrush and fluoridated toothpaste. The final mean pH was significantly higher than the initial mean pH (p < 0.001). A similar significant difference was observed among children without CL/P (p < 0.001). This finding is consistent with Rodríguez et al. [22], who reported that parent-supervised toothbrushing in children with CL/P promotes better overall oral hygiene and influences the composition of the oral microbiome. The mechanical action of toothbrushing - regardless of duration - contributes to differences in the microbiota between children with and without CL/P. Preventive interventions, such as proper toothbrushing, therefore, remain essential for maintaining good oral hygiene in children with CL/P. Although the increased risk of dental caries in this population is not fully understood, many potential risk factors are related to the difficulty of cleaning hard-to-reach areas.
The importance of saliva is underscored by the fact that individuals with salivary deficiencies - such as those with CL/P - are more prone to oral disease. Saliva contains a wide range of antimicrobial components, including lysozyme, lactoferrin, histatins, defensins, and secretory IgA, that help buffer pH and are continually renewed. Swallowing also helps clear food debris, desquamated cells, and microbial byproducts [23].
In dental caries, the biofilm shifts toward acidogenic and acid-tolerant bacteria (e.g., S. mutans and Lactobacillus spp.) that drive enamel demineralization. These organisms metabolize dietary sugars to acids, creating localized low pH (~5.5). If such acidic conditions persist without sufficient time for remineralization, carious lesions develop [22,23]. This mechanism may help explain our findings on the prevalence of dental caries in children with CL/P, as measured by the DMFT/dmft index [24]. On average, children with CL/P had eight carious teeth, whereas those without CL/P had two, a statistically significant difference (p < 0.001). Jiang et al. [25] suggest that the interplay between nasal and oral functions in individuals with CL/P may influence the oral microbiota, potentially disrupting its balance and increasing disease susceptibility. Recent studies similarly indicate that children with CL/P experience compositional shifts in the oral microbiota, which may contribute to their heightened risk of oral health complications.
Regarding the relationship between salivary pH variation before and after toothbrushing with fluoridated toothpaste and the presence of dental caries in children with and without CL/P, no statistically significant association was observed (p = 0.718). This finding is consistent with Reis de Souza et al. [10], who analyzed 45 patients with and without CL/P using test strips to measure salivary pH. They likewise found no significant difference in salivary pH between groups. However, they noted a tendency toward more acidic values in the CL/P group and recommended further research to clarify this issue
Further studies on the characteristics and properties of saliva in patients with CL/P are recommended to better understand its role in the prevention and control of dental caries, which is a common condition in this population. Based on the findings regarding saliva, preventive programs should be developed that incorporate these data to effectively prevent dental caries in children with CL/P.
Conclusion
Although children with cleft lip and palate exhibited a significantly greater change in salivary pH before and after toothbrushing than children without cleft lip and palate, this variation was not associated with dental caries.
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Financial Support
None.
Data Availability
The data used to support the findings of this study can be made available upon request to the corresponding author.
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Edited by
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Academic Editor:
Catarina Ribeiro Barros Alencar
