Salivary Function and Dental Changes During GLP-1 Therapy

Prospective Evaluation of Salivary Calcium Levels, Salivary Function, and Dental Hard Tissue Changes in Patients Receiving GLP-1 Receptor Agonist Therapy

People who use glucagon-like peptide-1 (GLP-1) receptor agonists, such as semaglutide and tirzepatide, may experience changes in their oral health. Some people report dry mouth, changes in saliva, and increased wear of their teeth after starting these medicines. However, little is known about whether these medicines affect saliva and dental hard tissues.

The purpose of this study is to evaluate changes in salivary calcium levels, salivary function, and dental hard tissues in adults who begin treatment with semaglutide or tirzepatide for obesity.

Approximately 40 participants will be enrolled before starting GLP-1 receptor agonist therapy. Oral examinations, standardized intraoral photographs, saliva samples, and body weight measurements will be obtained before treatment and again after three months. Saliva samples will be analyzed for calcium concentration, pH, and salivary flow rate. Dental hard tissue changes will be assessed using the Basic Erosive Wear Examination (BEWE) index.

The findings from this study may improve understanding of the effects of GLP-1 receptor agonists on oral health and help healthcare professionals identify and prevent possible dental complications during treatment.

Study Overview

• Status: Not yet recruiting
• Conditions: Obesity; Saliva Altered; Dental Erosion; Saliva Collection
• Intervention / Treatment: Procedure: Unstimulated Whole Saliva Collection; Procedure: Salivary Analysis; Procedure: Oral Examination and BEWE Assessment; Procedure: Standardized Intraoral Photography

Detailed Description

Glucagon-like peptide-1 (GLP-1) receptor agonists, including semaglutide and tirzepatide, have become widely used for the treatment of obesity because of their substantial effects on body weight reduction and metabolic control. As the use of these medications continues to increase, attention has shifted toward their potential systemic and oral adverse effects. Recent clinical reports and pharmacovigilance studies have described oral complaints such as xerostomia, hyposalivation, oral discomfort, altered taste perception, and dental problems in individuals receiving GLP-1 receptor agonist therapy. However, the biological mechanisms underlying these observations remain largely unknown.

Saliva is essential for maintaining oral homeostasis. It provides lubrication, buffering capacity, antimicrobial protection, and contributes to the remineralization of dental hard tissues through its mineral content, particularly calcium and phosphate ions. Alterations in salivary secretion, pH, or mineral composition may impair the protective functions of saliva, thereby increasing the susceptibility to dental erosion, enamel demineralization, and other hard tissue alterations. Although reduced salivary flow has been described in isolated reports of semaglutide users, prospective clinical evidence evaluating changes in salivary composition during GLP-1 receptor agonist therapy is currently lacking.

Weight loss associated with GLP-1 receptor agonists may also indirectly influence oral health. Gastrointestinal adverse effects, particularly nausea and vomiting, as well as changes in dietary habits, fluid intake, and gastroesophageal reflux symptoms, may increase exposure of dental tissues to acidic conditions. Furthermore, dehydration resulting from reduced oral intake or gastrointestinal symptoms may contribute to impaired salivary function. These factors may act individually or synergistically to influence the integrity of dental hard tissues during treatment.

This prospective observational cohort study aims to evaluate changes in salivary calcium concentration, salivary flow rate, salivary pH, and dental hard tissues in adults initiating semaglutide or tirzepatide therapy for obesity. Participants will undergo standardized oral examinations, body weight measurements, intraoral photography, and unstimulated whole saliva collection before treatment initiation and after three months of therapy. Dental hard tissue changes will be assessed using the Basic Erosive Wear Examination (BEWE) index, while saliva samples will be analyzed for calcium concentration, pH, and salivary flow rate using standardized laboratory procedures.

The primary objective of this study is to determine whether treatment with GLP-1 receptor agonists is associated with changes in salivary calcium concentration during the first three months of therapy. Secondary objectives include evaluating changes in salivary pH, salivary flow rate, dental hard tissue status assessed by BEWE, body weight, and standardized photographic findings. In addition, the study will investigate the relationships between weight loss, gastrointestinal symptoms, salivary alterations, and dental hard tissue changes.

Because prospective studies evaluating the oral effects of GLP-1 receptor agonists remain limited, this study is expected to provide novel clinical evidence regarding the potential impact of these medications on salivary function and dental hard tissues. The findings may contribute to the early recognition of oral changes during obesity pharmacotherapy and support the development of preventive strategies through collaboration between endocrinologists and dental professionals.

• Study Type: Observational
• Enrollment (Estimated): 40

Contacts and Locations

• Study Contact: Name: Yasemin B. ÖNDER, DDS, PhD; Phone Number: +905532502064; Email: ybyilmaz@gmail.com

Study Locations

• Turkey (Türkiye)
  • Merkez
    • Bilecik, Merkez, Turkey (Türkiye), 11100
      • Department of Periodontology, Bilecik Seyh Edebali University Faculty of Dentistry
      • Contact: Yasemin B. ÖNDER, DDS,pHD; Phone Number: 05532502064; Email: ybyilmaz@gmail.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

The study population will consist of adults (≥18 years) with obesity (BMI ≥27 kg/m²) who are prescribed semaglutide or tirzepatide for obesity management according to routine clinical practice. Participants will be recruited before initiating GLP-1 receptor agonist therapy at the Endocrinology and Metabolism outpatient clinic and will undergo standardized oral examinations and saliva assessments at baseline and after 3 months of treatment.

Description

Inclusion Criteria:

• Adults aged 18 years or older.
• Body mass index (BMI) ≥27 kg/m².
• Clinical decision by an endocrinologist to initiate semaglutide or tirzepatide therapy for obesity management.
• No previous treatment with GLP-1 receptor agonists.
• Willingness to participate and ability to provide written informed consent.
• Willingness to attend both the baseline and 3-month follow-up visits.

Exclusion Criteria:

• Previous use of any GLP-1 receptor agonist.
• History of head and neck radiotherapy.
• Sjögren syndrome or other systemic diseases affecting salivary gland function.
• Chronic kidney disease.
• Pregnancy or breastfeeding.
• Use of medications known to markedly affect salivary secretion.
• Active orthodontic treatment.
• Severe dental erosion requiring restorative treatment at baseline.
• Edentulism or the absence of anterior teeth required for dental hard tissue assessment.
• Inability or unwillingness to comply with the study protocol or attend the 3-month follow-up visit.
• History of eating disorders associated with recurrent self-induced vomiting (e.g., bulimia nervosa).
• Medical conditions causing persistent vomiting or severe gastroesophageal disease unrelated to GLP-1 therapy.

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Semaglutide Group; Adults with obesity who are prescribed semaglutide by an endocrinologist according to routine clinical indications. Participants will undergo baseline oral examination, standardized intraoral photography, body weight assessment, and unstimulated whole saliva collection before initiating treatment. The same evaluations will be repeated after 3 months of therapy. Saliva samples will be analyzed for calcium concentration, pH, and salivary flow rate, and dental hard tissue changes will be assessed using the Basic Erosive Wear Examination (BEWE) index.Changes in salivary calcium concentration, salivary pH, salivary flow rate, BEWE scores, body weight, and standardized intraoral photographs will be compared between baseline and the 3-month follow-up, as well as between the two treatment groups.	Procedure: Unstimulated Whole Saliva Collection; Unstimulated whole saliva will be collected for 10 minutes at baseline and after 3 months. Participants will refrain from eating, drinking, smoking, chewing gum, and performing oral hygiene procedures for at least 2 hours before sample collection. Salivary flow rate will be calculated, and saliva samples will be processed for pH measurement and calcium analysis.; Procedure: Salivary Analysis; Saliva samples will be centrifuged at 3,000 × g for 10 minutes at 4°C. Salivary pH will be measured, and the supernatant will be stored at -80°C until calcium concentration analysis.; Procedure: Oral Examination and BEWE Assessment; Standardized oral examinations will be performed at baseline and after 3 months. Dental hard tissue status will be evaluated using the Basic Erosive Wear Examination (BEWE) index by calibrated examiners.; Procedure: Standardized Intraoral Photography; Standardized intraoral photographs will be obtained at baseline and after 3 months using a predefined photographic protocol. Images will be coded and evaluated for dental hard tissue changes by blinded assessors.
Tirzepatide Group; Adults with obesity who are prescribed tirzepatide by an endocrinologist according to routine clinical indications. Participants will undergo baseline oral examination, standardized intraoral photography, body weight assessment, and unstimulated whole saliva collection before initiating treatment. The same evaluations will be repeated after 3 months of therapy. Saliva samples will be analyzed for calcium concentration, pH, and salivary flow rate, and dental hard tissue changes will be assessed using the Basic Erosive Wear Examination (BEWE) index.Changes in salivary calcium concentration, salivary pH, salivary flow rate, BEWE scores, body weight, and standardized intraoral photographs will be compared between baseline and the 3-month follow-up, as well as between the two treatment groups.	Procedure: Unstimulated Whole Saliva Collection; Unstimulated whole saliva will be collected for 10 minutes at baseline and after 3 months. Participants will refrain from eating, drinking, smoking, chewing gum, and performing oral hygiene procedures for at least 2 hours before sample collection. Salivary flow rate will be calculated, and saliva samples will be processed for pH measurement and calcium analysis.; Procedure: Salivary Analysis; Saliva samples will be centrifuged at 3,000 × g for 10 minutes at 4°C. Salivary pH will be measured, and the supernatant will be stored at -80°C until calcium concentration analysis.; Procedure: Oral Examination and BEWE Assessment; Standardized oral examinations will be performed at baseline and after 3 months. Dental hard tissue status will be evaluated using the Basic Erosive Wear Examination (BEWE) index by calibrated examiners.; Procedure: Standardized Intraoral Photography; Standardized intraoral photographs will be obtained at baseline and after 3 months using a predefined photographic protocol. Images will be coded and evaluated for dental hard tissue changes by blinded assessors.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in salivary calcium concentration	Change in salivary calcium concentration (mg/dL) measured in unstimulated whole saliva using a colorimetric biochemical assay between baseline and 3 months after initiation of semaglutide or tirzepatide therapy.	Baseline and 3 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in salivary pH	Change in unstimulated salivary pH measured using a digital pH meter between baseline and 3 months.	Baseline and 3 months
Change in unstimulated salivary flow rate	Change in unstimulated salivary flow rate (mL/min) calculated from saliva collected over a standardized 10-minute period between baseline and 3 months.	Baseline and 3 months
Change in dental hard tissue status	Change in dental erosive wear assessed using the Basic Erosive Wear Examination (BEWE) scoring system (score 0-18) between baseline and 3 months.	Baseline and 3 months
Change in body mass index	Change in body mass index (kg/m²) calculated from measured body weight and height between baseline and 3 months.	Baseline and 3 months
Change in body weight	Change in body weight (kg) measured using a calibrated digital scale between baseline and 3 months.	Baseline and 3 months

Collaborators and Investigators

• Sponsor: Bilecik Seyh Edebali Universitesi

Publications and helpful links

General Publications

• Kim YJ, Kim YB, Kim S, Choi TY, Park HK, Choi SY. Chlorpromazine induces hyposalivation by inhibiting muscarinic Ca2+ signaling in salivary glands. Naunyn Schmiedebergs Arch Pharmacol. 2026 Jan;399(1):941-951. doi: 10.1007/s00210-025-04438-8. Epub 2025 Jul 23.
• Mawardi HH, Almazrooa SA, Dakhil SA, Aboalola AA, Al-Ghalib TA, Eshky RT, Niyazi AA, Mawardi MH. Semaglutide-associated hyposalivation: A report of case series. Medicine (Baltimore). 2023 Dec 29;102(52):e36730. doi: 10.1097/MD.0000000000036730.
• Barac M, Roganovic J. GLP-1 Receptor Signaling and Oral Dysfunction: A Narrative Review on the Mechanistic Basis of Semaglutide-Related Oral Adverse Effects. Biology (Basel). 2025 Nov 23;14(12):1650. doi: 10.3390/biology14121650.

Study record dates

Study Major Dates

• Study Start (Estimated): August 17, 2026
• Primary Completion (Estimated): October 21, 2026
• Study Completion (Estimated): March 17, 2027

Study Registration Dates

• First Submitted: July 14, 2026
• First Submitted That Met QC Criteria: July 17, 2026
• First Posted (Actual): July 22, 2026

Study Record Updates

• Last Update Posted (Actual): July 22, 2026
• Last Update Submitted That Met QC Criteria: July 17, 2026
• Last Verified: July 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Stomatognathic Diseases; Nutrition Disorders; Overnutrition; Body Weight; Tooth Diseases; Overweight; Tooth Demineralization; Tooth Wear; Pathological Conditions, Signs and Symptoms; Nutritional and Metabolic Diseases; Signs and Symptoms; Obesity; Tooth Erosion; Dentistry; Diagnosis, Oral
• Other Study ID Numbers: BSEU-ONDER-003

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: De-identified individual participant data underlying the primary study results will be shared upon reasonable request. The dataset will include demographic characteristics, body weight, body mass index, treatment group, medication dose, salivary calcium concentration, salivary pH, salivary flow rate, BEWE scores, and other coded clinical variables. The study protocol, statistical analysis plan, and data dictionary will also be available. Original photographs and biological specimens will not be shared. Data access will require approval of a scientifically sound research proposal and a data-sharing agreement.
• IPD Sharing Time Frame: Baseline-3 months
• IPD Sharing Access Criteria: Access will be granted only to qualified researchers who submit a methodologically sound research proposal. Requests will be reviewed by the principal investigator and study investigators. Approved researchers will receive de-identified individual participant data, the study protocol, statistical analysis plan, and data dictionary after signing a data-sharing agreement. Data will be transferred through secure electronic methods in accordance with institutional policies, applicable regulations, and participant confidentiality requirements.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ICF; CSR

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No