Complete tooth loss is a significant oral health issue, especially in older adults, and is an ongoing requirement for complete denture rehabilitation.[1] According to a World Health Organization (WHO) estimate, 7% of the world's population is completely edentulous, and this figure increases to 23% among those 60 years and above.[2] More recently, US survey data have also shown

a progressive age trend of decreasing dentition status from the youngest age group to ≥75 years of age, with 11.4% of 65- to 74-year-old adults and 19.7% of adults ≥75 years old being edentulous.[3] Based on a WHO SAGE study of over 25,000 adults aged ≥50 years, the overall prevalence of edentulism in these countries was 10.9%.[4]

Complete Dentures are still one of the most common treatment methods for restoring mastication, speech, facial support, and oral function in edentulous persons.[5] Tooth loss, however, sets in a lifelong sequence of alveolar ridge residual ridge resorption (RRR) that results in a progressive decrease in the height and width of the alveolar ridge.[6] RRR is thought to be chronic, progressive, and essentially irreversible, but the severity and speed are very different from person to person.[7] The mandibular ridge is more likely to be affected by clinically significant resorption than the maxillary ridge, which can gradually affect the stability, retention, and support of the dentures.[8] Thus, denture looseness, difficulty in chewing food, and oral complaints may become more and more severe as the patient progresses.[9]

Clinical importance of denture use and residual ridge resorption is the direct application of functional forces on the underlying residual alveolar bone and mucosa.[10] Resorption can be affected by several factors such as age, sex, length of edentulism, general health, bone quality, previous periodontal disease, denture loading, etc., and denture design and use.[11] There is also evidence that longer denture wearing time is correlated with more ridge resorption.[8] A case-control study revealed a significantly higher incidence of maxillary and mandibular ridge resorption among the cases who had worn complete dentures for over 5 years compared to the matched controls who were edentulous and had not worn dentures. The density loss due to severe ridge resorption was mainly seen in denture wearers.[12]

Although it is known that residual ridge resorption is biologically significant, the amount of ridge resorption in the period of complete denture use, and the relationship between the duration of complete denture use and the amount of ridge resorption, is clinically relevant and not well understood, especially in routine clinical populations. Clinicians can use this information to better determine if patients who use dentures longer have higher rates of denture ridge reduction, and can make better decisions on replacing or modifying dentures, impression procedures, and the long-term care of prosthodontic follow-up. This is particularly significant in environments where a person is wearing the same dentures for extended periods of time due to cost, availability, or treatment.

Hence, the present study was undertaken to check the correlation between residual ridge resorption and time of complete denture usage. This study's goal is to provide clinically relevant data in terms of ridge resorption that can be correlated with years of denture use, which could assist with timely assessment and replacement of dentures and enhance long-term prosthetic outcomes in completely edentulous patients. The present study was designed to investigate the relationship between residual ridge resorption and complete denture usage period in completely edentulous individuals.

A cross-sectional analytical study was carried out to find the correlation between the duration of complete denture use and the residual ridge resorption among the completely edentulous patients. The duration of use of complete dentures was evaluated, and the amount of residual ridge resorption at the time of examination was assessed. The study was conducted at Medical Testing Institute (MTI), Mardan Medical Complex (MMC), Mardan for 6 months, from 1st September, 2025 to 28th February, 2026. The sample size was determined with the single population proportion formula in OpenEpi version 3.01. The prevalence of 60% was taken from a recent study carried out among totally edentulous patients, in which 60% of the patients had severe residual ridge resorption.[13] A 95% confidence level and 10% absolute margin of error were used. According to the calculation, the minimum number of samples required was 103. A non-probability consecutive sampling technique was used. Patients of either sex, aged 50–75 years, who were completely edentulous in the maxillary and mandibular arches and had been using conventional complete dentures for at least one year were included. Patients who were clinically identifiable with complete dentures that had an approximate length of time they had worn the dentures could be established from their history were eligible. Patients who were willing to undergo clinical and radiographic evaluation of the residual ridges and had given informed written consent were also included. Patients with a history of implant-supported dentures, previous alveolar ridge augmentation, or other pre-prosthetic surgery were excluded. Patients with osteoporosis receiving active treatment, a history of other conditions or medications known to significantly impact bone metabolism, long-term corticosteroid therapy, or bisphosphonate therapy/antiresorptive medications were excluded. Patients were also excluded if they had received radiotherapy in the jaw area, had an active infection in the mouth, had any pathological changes in the residual ridge, or had a previous dental fracture in the jaws. They were excluded if patients indicated that they had not been wearing the denture for a certain period of time or if they opted not to have the denture taken for radiographs and/or were unable to give informed consent. Eligible participants gave informed written consent, then were interviewed on a structured data collection proforma. Sociodemographic data including age and sex. Duration of complete denture use was obtained from the patients' interview and previous dental records, if available. Denture use duration was reported as completed years from the delivery date of the most recent and first complete denture, respectively. Other denture-related data such as the frequency of denture usage, length of time dentures are worn per day, and denture replacement history were also recorded. After this, a standard clinical examination was then conducted to evaluate the remaining ridges. The morphology of the maxillary and mandibular ridges was assessed for their height, width, contour, and the extent of resorption. The intraoral/extraoral measurements and/or the intraoral/extraoral radiographs were used in a standardized manner according to the study protocol to evaluate residual ridge resorption. A standard technique was used for radiographic assessment, with the same position and exposure factors applied to all, to the extent possible. The amount of residual ridge reduction was documented at predetermined anatomical landmarks. If a radiographic measurement was performed, these results were reported in mm: the higher the reduction in ridge height, the higher the residual ridge resorption. The results of the data collected were input and analyzed using SPSS Windows version 26.0. The Shapiro–Wilk test was used to determine the distribution of continuous variables, such as age, duration of complete denture use, and measurement of residual ridge resorption. Continuous data were reported as mean ± SD, except for data that were normally distributed. Categorical variables (sex and important clinical characteristics) were given as frequencies and percentages. The main focus of the primary analysis was the effect of complete denture duration on the amount of residual ridge resorption. Pearson correlation coefficient was applied for normally distributed variables, while the Spearman rank correlation coefficient was applied in the absence of the normality assumption. The strength and direction of correlation along with the associated p value were reported. Participants were also grouped by duration of denture use (1-5 years, 6-10 years, and >10 years), and residual ridge resorption measurements were compared between these groups, using one-way ANOVA for normally distributed data. Potential confounding factors such as age and sex were taken into account in the analysis. The multiple linear regression model was employed to see if the amount of residual ridge resorption was independently predicted by the duration of complete denture use after adjusting for the other predictor variables. A p-value of ≤0.05 was deemed to be statistically significant, and two-tailed tests were used throughout.

A total of 103 completely edentulous patients were included in the study. Demographic and denture-related characteristics, such as age, gender, duration of denture use, daily wearing time, previous denture replacement, and overall severity of residual ridge resorption, are summarized in Table 1.

In the clinical and radiographic evaluation, residual ridge resorption was seen in varying amounts in both the upper and lower dentition. The distribution of resorption according to severity and the corresponding ridge measurements are summarized in Table 2.

The significant association between the duration of use of the complete denture and the amount of RIR indicated that the longer the use of the complete denture, the greater was the RIR. Patients were divided into groups based on the duration of denture use, and comparisons showed that there were significant differences in the resorption of the mandibular and maxillary ridges between the various duration groups. The distribution of resorption severity according to denture-use duration is presented in Table 3.

The duration of denture use in both arches was positively correlated with the level of residual ridge resorption, with a statistically significant relationship for both. The duration of denture use was still found to be statistically significant in multivariable analysis after the selected demographic and denture-related variables were adjusted. The detailed correlation and regression findings are presented in Table 4.

Table 1. Sociodemographic and Denture-Related Characteristics of Study Participants (n=103)

Table 2. Clinical and Radiographic Assessment of Residual Ridge Resorption (n=103)

Table 3. Association between Duration of Complete Denture Use and Residual Ridge Resorption

Table 4. Correlation and Regression Analysis of Duration of Denture Use with Residual Ridge Resorption

A total of 103 completely edentulous patients were included in the study. Demographic and denture-related characteristics, such as age, gender, duration of denture use, daily wearing time, previous denture replacement, and overall severity of residual ridge resorption, are summarized in Table 1. In the clinical and radiographic evaluation, residual ridge resorption was seen in varying amounts in both the upper and lower dentition. The distribution of resorption according to severity and the corresponding ridge measurements are summarized in Table 2. The significant association between the duration of use of the complete denture and the amount of RIR indicated that the longer the use of the complete denture, the greater was the RIR. Patients were divided into groups based on the duration of denture use, and comparisons showed that there were significant differences in the resorption of the mandibular and maxillary ridges between the various duration groups. The distribution of resorption severity according to denture-use duration is presented in Table 3. The duration of denture use in both arches was positively correlated with the level of residual ridge resorption, with a statistically significant relationship for both. The duration of denture use was still found to be statistically significant in multivariable analysis after the selected demographic and denture-related variables were adjusted. The detailed correlation and regression findings are presented in Table 4. Table 1. Sociodemographic and Denture-Related Characteristics of Study Participants (n=103) n (%) / Mean ± SD Age (years) 63.4 ± 7.2 Age group 50–59 years 27 (26.2) 60–69 years 51 (49.5) 70–75 years 25 (24.3) Sex Male 56 (54.4) Female 47 (45.6) Duration of complete denture use (years) 8.1 ± 4.6 Duration of denture use 1–5 years 34 (33.0) 6–10 years 41 (39.8) >10 years 28 (27.2) Daily denture wearing time (hours/day) 12.6 ± 3.1 Previous denture replacement 48 (46.6) No previous denture replacement 55 (53.4) Severe residual ridge resorption 62 (60.2) Non-severe residual ridge resorption 41 (39.8) Table 2. Clinical and Radiographic Assessment of Residual Ridge Resorption (n=103) Residual Ridge Resorption Mean ± SD / n (%) Mandibular ridge height (mm) 17.8 ± 3.6 Mild resorption 23 (22.3) Moderate resorption 39 (37.9) Severe resorption 41 (39.8) Maxillary ridge resorption Mild 31 (30.1) Moderate 45 (43.7) Severe 27 (26.2) Mean mandibular ridge resorption measurement (mm) 7.4 ± 2.8 Mean maxillary ridge resorption measurement (mm) 5.2 ± 2.1 Table 3. Association between Duration of Complete Denture Use and Residual Ridge Resorption Duration of Complete Denture Use and Residual Ridge Resorption 1–5 years (n=34) 6–10 years (n=41) >10 years (n=28) p-value Mean mandibular ridge resorption (mm) 5.8 ± 1.9 7.2 ± 2.3 9.4 ± 2.6 <0.001 Mean maxillary ridge resorption (mm) 4.1 ± 1.6 5.0 ± 1.8 6.8 ± 2.0 <0.001 Severity of mandibular resorption Mild 14 (41.2) 8 (19.5) 1 (3.6) Moderate 16 (47.1) 17 (41.5) 6 (21.4) Severe 4 (11.8) 16 (39.0) 21 (75.0) <0.001 Severe maxillary resorption 5 (14.7) 10 (24.4) 12 (42.9) 0.024 Table 4. Correlation and Regression Analysis of Duration of Denture Use with Residual Ridge Resorption Duration of Denture Use with Residual Ridge Resorption Correlation/β 95% CI p-value Duration of denture use vs. mandibular ridge resorption r = 0.61 0.47–0.72 <0.001 Duration of denture use vs. maxillary ridge resorption r = 0.48 0.32–0.62 <0.001 Multiple linear regression: mandibular resorption Duration of denture use (per year) β = 0.31 0.22–0.40 <0.001 Age (per year) β = 0.08 0.01–0.15 0.026 Male sex β = 0.21 −0.18–0.60 0.287 Previous denture replacement β = −0.17 −0.54–0.20 0.364 Model R² 0.46 — <0.001

The duration of complete denture use was significantly related to the amount of ridge resorption that occurred, as longer wearing times of complete dentures were correlated with increased amounts of ridge resorption. The results indicate that complete denture rehabilitation should not be considered a treatment which is completed once and for all; rather, the supporting ridge undergoes progressive anatomical change. The morphology of the residual ridges and denture fit should be assessed regularly, especially in long-term denture wearers, and can aid timely intervention and reduce the loss of prosthetic function. Longitudinal studies are warranted to establish the rate and determinants of this progressive change.

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