Abstract
Aim:
Complete dentures (CDs) are fabricated to rehabilitate the edentulous. Severe residual ridge resorption (RRR) compromises CD functionality, adversely affecting function, appearance, systemic health, and quality of life.
Settings and Design:
The purpose of this study was to assess the benefit, if any, of calcium and Vitamin D supplementation on the rate of RRR. Retarding RRR would improve treatment prognosis and make CD fabrication less demanding.
Materials and Methods:
This longitudinal, parallel, open-label randomized study was conducted in the Department of Prosthodontics of the institute. One hundred and fifty edentulous subjects underwent bone mineral density (BMD) assessment followed by CD fabrication to measure RR height and width with computerized tomographic (CT) scans. Subjects were randomized to oral supplementation group – S, given combined Vitamin D and calcium daily, and nonsupplementation group – NS. Subjects from both the groups were followed up with repeat BMD test and CT scan after 12 months. Mean BMD, RR height and width, and RRR values were collected, analyzed, and compared for the two groups using STATA 17.
Statistical Analysis Used and Results:
Baseline mean T-score, RR height, and RR width were − 1.84, 22.30 mm, and 4.25 mm, respectively, for the sample. In both Groups S and NS, a statistically significant decrease in mandibular RR height (P = 0.000 for both) and width (P = 0.027 and 0.003, respectively) was observed at 1-year follow-up. There was a statistically insignificant difference between Groups S and NS for mean BMD, T-score, RR height and width, and RRR at both baseline and 12-month follow-up. One-year RRR rate for Group S (1.30 mm) was insignificantly lesser than for group NS (1.33 mm).
Conclusion:
Short-term oral calcium and Vitamin D supplementation was ineffective in reducing RRR and improving BMD.
Keywords: Absorptiometry, alveolar resorption, bone mineral density, calcium, dietary supplementation, dual-energy X-ray, Vitamin D
INTRODUCTION
The world is aging rapidly. Aging inevitably results in increasing systemic and oral health problems. Although edentulism is reportedly declining in developed countries, it is still a major global health issue.[1] The World Health Organization (WHO) pointed out that good oral condition is important for healthy aging, more so in the disadvantaged.[2,3]
Edentulism (loss of all teeth) leads to functional and esthetic impairment, and psychological and social disability, besides affecting overall health.[4] Loss of teeth from the jaw leaves behind a residual alveolar ridge (RR).[5] Once an individual is rendered edentulous, he/she has to depend on complete dentures (CDs) for proper mastication and appearance.[6] Such a prosthesis depends on the shape and size of the residual ridge for proper retention, stability, and function.[7] A removable denture made by the very best clinician on a small residual ridge has high chances of failure.[8,9] This happens because the resulting denture is ill-fitting or “floating” because of which it becomes nonfunctional.[10,11,12,13]
Residual ridge resorption (RRR) is a chronic, progressive, and irreversible multifactorial process of alveolar bone depletion.[14,15,16,17,18] The etiology of RRR is still not clear.[19] It may be caused by local or systemic factors or a combination. These factors may be organized into four major categories: anatomic amount and quality of residual ridge; metabolic-bone formation and resorption factors; functional – (a) how long, how frequently, with what intensity and in which direction were forces applied to the residual ridge, (b) denture coverage area, and c) number, width, and form of teeth.[20] RRR causes serious problems for the clinician in terms of making a well-functioning denture and in turn for the patient, who suffers from problems in mastication, nutrition, speech, appearance, and diminished quality of life. Methods advocated for reducing or preventing RRR include optimizing systemic health, modifying impression technique, using the neutral zone technique, employing broad denture base coverage, decreasing number of dental units or their buccolingual width, using monoplane teeth, applyingh the neutrocentric concept, increasing interocclusal distance at rest, retaining some teeth as overdenture abutments and/or instituting an implant supported prosthesis.[21,22,23] Some of these have limited success in prevention, while others cannot be implemented in every patient.
Various researchers such as Jowsey, Stein and Beller, and Albanese reported that low calcium and Vitamin D levels and a reduced calcium–phosphorus ratio were factors in generalized bone loss, and calcium supplementation may diminish such loss.[24,25,26] Vitamin D aids calcium absorption from the alimentary tract and helps maintain blood calcium and phosphate concentration to ensure normal bone mineralization, growth, and remodeling. Many studies have shown that combined calcium and Vitamin D supplementation results in a reduction in fracture risk by improving bone quantity and quality.[24,25,26]
Calcium is found in food, in supplements, and in some medications like antacids. All but 1% of the systemic calcium supply is stored in the skeletal system and dentition, where it is essential for structure and function.[27] A decrease in calcium reserve may mean a reduction in bone mass and a corresponding reduction in bone strength.[28,29]
However, no conclusive evidence exists regarding the effect of Vitamin D and calcium supplementation on alveolar resorption.[30,31,32] Therefore, keeping in mind the positive outcomes of calcium and Vitamin D on quality and quantity of bone, this study was planned to assess the effects of fixed-dose calcium and Vitamin D supplementation on RRR in edentulous aging patients following prosthodontic rehabilitation with removable CDs. The null hypothesis was that calcium and Vitamin D supplementation has no effect on RRR in aging edentulous patients.
MATERIALS AND METHODS
The proposed design was a longitudinal, parallel, open-label randomized study with an allocation ratio of 1:1, prepared in conformance with CONSORT guidelines 2010. The participants of this study were edentulous patients, intervention comprised oral calcium and Vitamin D supplementation, the comparator group did not receive any intervention, and the outcome was reduction, if any, in RRR rate. The study was initiated after obtaining institutional ethical approval (Reference No. 1643/R. Cell-11) and clinical trial registry (CTRI/2017/09/009626). The target population for the study was aging completely edentulous subjects aged 40 years and above, visiting the Department of Prosthodontics of the institute for removable prosthodontic rehabilitation. The total sample size for a two-sided hypothesis with a power of 80% was approximately 150, including loss to follow-up of 20% (Zα =1.96, Zβ =0.84, σ =2 mm, Δ =1 mm) by the formula n = 2 × ([Zα + Zβ]2× σ2)/Δ2; σ signifies standard deviation and Δ signifies significant change, i.e., n = 2 × ([1.96 + 0.84] 2 × 22)/12 = 2 × 7.84 × 4 = 63 subjects per group approximately [Figure 1].
Figure 1.
Consort flow diagram
Inclusion criteria were (1) completely edentulous patients who were nonsmokers and nonalcohol consumers aged 60 years or above, who were not under medication for any oral, metabolic, bone, kidney, or hormonal disorder, or previous calcium and/or Vitamin D supplementation; (2) all patients who were edentulous for more than 1 year, as residual ridge reduces in size most swiftly in the first 6 months, which gradually decreases to a steady rate; (3) Class I and 2 edentulous subjects with moderate alveolar ridge atrophy; and (4) subjects classified as philosophical as per MM house, as such patients recognize that they play an important part in the treatment. Such patients are more compliant with follow-up and instructions.
The exclusion criteria were 1) Patients on drugs that may interfere with Calcium or Vitamin D metabolism such as Biphosphonates, Levothyroxine, Phenobarbital, Phenytoin, Tiludronate disodium, Thiazide like diuretics, Antacids having aluminum and/ or magnesium content, mineral oil containing stimulant laxatives, Glucocorticoids, Orlistat, Cholestyramine and hormone replacement therapy. 2) Patients suffering from any oral, metabolic, bony, liver, kidney or hormonal disorder such as Osteitis Fibrosa, Paget's disease, Diabetes, Renal dysfunction, Hyper/Hypothyroidism, Hyper/hypoparathyroidism, Pituitary gland dysfunctions, Prostatic or Ovarian Cancers etc. 3) Patients having smoking and/or alcohol drinking habit. 4) Patients on previous Calcium or Vitamin D supplements. 5) Previous denture wearers and patients with resorbed residual ridges or unfavorable ridge relations.
Written consent was obtained from all subjects. The age, gender, and duration of edentulism of the subjects were recorded, and data were anonymized. The subjects first underwent a dual-energy X-ray absorptiometry (DEXA) bone mineral density (BMD) test for calcium level of bone (g/cm2; lunar DPX DXA system). DEXA is considered the gold standard for BMD measurement.[33,34,35] Following this, upper/lower CDs were constructed to satisfy the classification of acceptable fabrication criteria based on stability, retention, occlusion, articulation, and vertical dimension.[36]
Cone-beam computerized tomography (CBCT) scans were made for quantitative analysis of mandibular residual ridge. CT scans of the patient were made with the CDs in position immediately postfabrication by paralleling the gantry tilt scan to the occlusal plane of the dentures.[37,38,39] This was done to ensure that there were no dimensional variations because of angular discrepancies in the subsequent scan. The occlusal plane was identified with the help of radiopaque inserts in the denture. Radiopaque markers (gutta-percha) were inserted at three points of interest in the mandibular denture (incisor and molar areas) to measure the height and width of residual mandibular ridge consistently and accurately in the same patient at baseline.[40]
Postinsertion instructions and appointments were administered routinely, and the patients were asked to report regularly at 2-month interval for monitoring and checkup. Patients were randomized into two groups (n = 75 each; total sample size 150) with an equal number of male and female subjects, using block randomization with stratification protocol to avoid gender bias. A free online randomization sequence generator software was used for this open-label study. The first group (supplementation group – Group S) was given combined Vitamin D (500 i.u.) and calcium (1000 mg elemental) supplements (tablet Coxcal 500; Coxswain Healthcare) orally in two daily divided doses for 12 months; the second group (nonsupplementation group – Group NS) received no supplementation therapy during the study period. All patients were advised to take medicine in the morning and evening after meals. The study was conducted in an open-label manner. Patients were advised to maintain their diet and supplementation pattern rigorously throughout the study and their compliance was regularly monitored at 2-month intervals. Each patient was followed up with DXA and quantitative evaluation of the residual ridge by repeat CT scan 12 months after the first evaluation.
Mean T-score, BMD, RR height, and RR width values for the whole sample and different age and gender groups were obtained at baseline. The correlation of mean RR height and width with BMD and duration of edentulism at baseline, if any, was assessed. Demographic details of patients who completed the study were compiled. Mean BMD, T score, and RR dimension values for Groups S and NS at baseline and follow-up, with differences, if any, were evaluated. The mean RRR for both Groups S and NS was calculated and compared by subtracting mean RR dimension (mean of height and width in mm at earmarked three points) 1 year post denture fabrication from the initial dimension.
Statistical analysis
Statistical analysis was done with STATA version 17 (© 2024 StataCorp LLC, USA), and P < 0.05 was considered statistically significant. The variables were analyzed using mean, standard deviation, one-way analysis of variance test, Kruskal–Wallis equality-of-populations rank, Mann–Whitney U-test with Welch correction, Wilcoxon signed rank test, Pearson's correlation coefficient, paired sample t-test, and independent-sample t-test with Welch correction.
RESULTS
Eighty males (53.33%) and 70 females (46.67%) were recruited, with there being 40 males and 35 females in both Groups S and NS. Baseline mean BMD, T-score, and mandibular RR height and width were 1.03 g/cm3, −1.84, and 22.30 mm and 4.25 mm, respectively [Table 1]. No statistically significant effect of age was observed on mean BMD, T-score, and RR width at baseline when tested at 5% level of significance, though RR height was found to significantly decrease with increasing age [Table 2]. Table 3 shows significantly lower mean BMD and T-scores for female subjects compared to males.
Table 1.
Mean variable values for sample at baseline (n=150)
| Variables | Mean±SD |
|---|---|
| Age (years) | 61.52±9.85 |
| Height (mm) | 158.14±10.68 |
| Weight (kg) | 58.71±11.94 |
| T-score | −1.84±1.21 |
| BMD (g/cm3) | 1.03±0.10 |
| Mean RR height (mm) | 22.30±5.38 |
| Mean RR width (mm) | 4.25±1.46 |
BMD: Bone mineral density, RR: Residual ridge, SD: Standard deviation
Table 2.
Variation in mean T-score, bone mineral density, and mean residual ridge height and width with age at baseline (n=150)
| Age (years) | Mean±SD |
|||
|---|---|---|---|---|
| T-score | BMD# | Mean RR height# | Mean RR width | |
| 40–44 (n=7) | −1.27±0.64 | 1.05±0.06 | 25.47±5.23 | 4.16±1.31 |
| 45–49 (n=10) | −1.98±1.22 | 1.01±0.08 | 24.16±3.90 | 3.94±0.94 |
| 50–54 (n=13) | −1.28±1.29 | 1.08±0.08 | 23.71±4.17 | 4.11±1.48 |
| 55–59 (n=19) | −1.94±0.87 | 1.02±0.09 | 22.40±5.87 | 4.81±2.19 |
| 60–64 (n=40) | −1.87±1.16 | 1.03±0.10 | 22.37±5.50 | 3.84±1.28 |
| 65–69 (n=24) | −2.14±1.44 | 1.01±0.12 | 21.66±6.09 | 4.68±1.38 |
| 70–74 (n=20) | −1.91±1.56 | 1.01±0.13 | 21.11±5.46 | 4.55±1.13 |
| ≥75 (n=17) | −1.77±0.88 | 1.04±0.08 | 20.91±4.92 | 3.95±1.41 |
| P | 0.6078 | 0.6551 | 0.0437 | 0.1672 |
#One-way ANOVA. Kruskal–Wallis equality-of-populations rank test. P>0.05, not significant, P≤0.05 significant, P≤0.001 highly significant. BMD: Bone mineral density, RR: Residual ridge, SD: Standard deviation
Table 3.
Variation in mean T-score, bone mineral density, and residual ridge height and width with gender at baseline (n=150)
| Gender | Mean±SD |
|||
|---|---|---|---|---|
| T-score | BMD$ | Mean RR height# | Mean RR width# | |
| Male (n=80) | −1.78±0.14 | 1.05±0.01 | 21.82±5.26 | 4.40±1.57 |
| Female (n=70) | −1.90±0.13 | 1.00±0.01 | 22.86±5.50 | 4.08±1.31 |
| P | 0.05* | 0.006* | 0.517 | 0.300 |
#Mann–Whitney U-test with Welch correction. *Significant or highly significant. $Independent sample t-test. P>0.05 not significant, P≤0.05 significant, P≤0.001 highly significant. BMD: Bone mineral density, RR: Residual ridge, SD: Standard deviation
Mean residual ridge height significantly decreased with diminishing T-score/BMD [Table 4]. No significant correlation between duration of edentulism and mean RR height and width could be established [Table 5]. Thirty-four patients were lost to follow-up, with a sample attrition of 22.7%. The gender distribution and mean age of Group S and NS subjects who completed the study are given in Table 6.
Table 4.
Variation in mean residual ridge height and width with T-score at baseline (n=150)
| Variables | Mean±SD |
|
|---|---|---|
| Mean residual ridge height | Mean residual ridge width | |
| Normal-T-score−1–+1 (n=43; 28.7%) | 23.63±4.73 | 4.14±1.13 |
| Osteopenia-T-score−1–−2.5 (n=69; 46%) | 22.30±5.27 | 4.39±1.31 |
| Osteoporosis-T-score ≤−2.5) (n=38; 25.3%) | 20.81±5.99 | 4.13±1.97 |
| P | 0.017 | 0.389 |
Kruskal–Wallis equality-of-populations rank test, P>0.05 not significant, P≤0.05 significant, P≤0.001 highly significant. SD: Standard deviation
Table 5.
Effect of duration of edentulism on mean residual ridge height and width for sample (n=150)
| Duration of edentulism (years) | Mean residual ridge height | Mean residual ridge width |
|---|---|---|
| 1–4 | 22.89±4.18 | 3.88±1.38 |
| 5–9 | 22.27±5.35 | 4.25±1.37 |
| >10 | 22.07±6.04 | 4.44±1.64 |
| P | 0.966 | 0.535 |
Kruskal–Wallis, Pearson’s correlation coefficient: Period versus height−0.10, Period versus width−0.014; P>0.05 not significant, P≤0.05 significant, P≤0.001 highly significant
Table 6.
Demographic details of patients who completed the study (n=116)
| Variables (n=116) | Group significant (n=60) | Group NS (n=56) |
|---|---|---|
| Age (mean±SD) | 61.58±7.62 | 61.75±8.87 |
| Gender, n (%) | ||
| Male | 28 (46.6) | 35 (62.5) |
| Female | 32 (53.3) | 21 (37.5) |
NS: Nonsupplementation, SD: Standard deviation
Tables 7 and 8 show a statistically significant decrease in anterior, posterior, and mean residual ridge height as well as width, for both Groups S and NS, between baseline and 12-month evaluation appointments. However, for both the groups, there was an insignificant difference in mean BMD and T-scores between the two evaluations.
Table 7.
Mean bone mineral density, T-score, and residual ridge height and width values for supplementation group (n=60)
| Group S | Mean±SD |
P | |
|---|---|---|---|
| 1st visit | Follow-up | ||
| BMD (g/cm3) | 1.04±0.02 | 1.04±0.02 | 0.707 |
| T-score# | −1.97±1.47 | −1.94±1.28 | 0.520 |
| Height (posterior) (mm) | 20.02±1.21 | 18.84±1.20 | ≤.001 |
| Height (anterior)# (mm) | 20.71±5.03 | 19.33±4.65 | 0.000 |
| Mean RR height (mm) | 20.25±1.18 | 18.95±1.14 | 0.000 |
| Width (posterior) (mm) | 5.37±0.54 | 5.01±0.45 | 0.045 |
| Width (anterior) (mm) | 5.02±0.48 | 4.87±0.52 | 0.049 |
| Mean RR width (mm) | 5.25±0.43 | 4.89±0.37 | 0.027 |
#Wilcoxon signed rank test. Paired sample t-test. P>0.05 not significant, P≤0.05 significant, P≤0.001 highly significant. BMD: Bone mineral density, RR: Residual ridge, SD: Standard deviation, S: Supplementation
Table 8.
Mean bone mineral density, T-score, and residual ridge height and width values for nonsupplementation group (n=56)
| Group NS | Mean±SD |
P | |
|---|---|---|---|
| 1st visit | Follow-up | ||
| BMD (g/cm3) | 1.06±0.02 | 1.06±0.02 | 0.793 |
| T-score | −1.67±1.36 | −1.66±1.08 | 0.793 |
| Height (posterior) (mm) | 22.5±4.70 | 21.32±4.67 | 0.004* |
| Height (anterior) (mm) | 24.03±5.02 | 22.37±5.14 | 0.000* |
| Mean RR height (mm) | 23.01±1.14 | 21.67±1.15 | 0.000* |
| Width (posterior) (mm) | 5.21±1.76 | 4.73±1.62 | 0.012* |
| Width (anterior) (mm) | 4.41±0.29 | 3.88±0.34 | 0.019* |
| Mean RR width (mm) | 4.95±0.32 | 4.48±0.28 | 0.003* |
*Significant or highly significant. Paired sample t-test. P>0.05 not significant, P≤0.05 significant, P≤0.001 highly significant. BMD: Bone mineral density, RR: Residual ridge, SD: Standard deviation, NS: Nonsupplementation
No statistically significant difference in mean BMD, T-score, RR height and width (anterior, posterior, and mean), and RRR (height and width) before or after supplementation could be seen between the two groups [Table 9]. One-year follow-up RRR (height) was found to be 1.30 and 1.33 mm for Groups S and NS, respectively; RRR (width) was found to be 036 and 0.46 mm for Groups S and NS, respectively.
Table 9.
Comparative mean bone mineral density, T-score, and residual ridge height and width in supplementation versus nonsupplementation group (n=116)
| Variables | Mean±SD |
P | |
|---|---|---|---|
| Group S | Group NS | ||
| BMD-first visit (g/cm3) | 1.04±0.02 | 1.06±0.02 | 0.554 |
| BMD-follow-up (g/cm3) | 1.04±0.02 | 1.06±0.02 | 0.573 |
| T-score-first visit | −1.97±0.35 | −1.67±0.34 | 0.548 |
| T-score-follow-up | −1.94±0.31 | −1.66±0.27 | 0.506 |
| Height (posterior)-first visit (mm) | 20.02±1.21 | 22.50±1.17 | 0.155 |
| Height (anterior)-first visit (mm) | 20.71±1.22 | 24.03±1.25 | 0.067 |
| Mean RR height-first visit (mm) | 20.25±1.18 | 23.01±1.14 | 0.106 |
| Height (posterior)-follow-up (mm) | 18.84±1.20 | 21.32±1.16 | 0.151 |
| Height (anterior)-follow-up (mm) | 19.33±1.12 | 22.37±1.28 | 0.084 |
| Mean RR height-follow-up (mm) | 18.95±1.14 | 21.67±1.15 | 0.105 |
| Mean RRR (height#) (mm) | 1.30±0.11 | 1.33±0.05 | 0.775 |
| Width (posterior)-first visit (mm) | 5.37±0.54 | 5.21±0.44 | 0.826 |
| Width (anterior)-first visit (mm) | 5.02±0.48 | 4.41±0.29 | 0.304 |
| Mean RR width-first visit (mm) | 5.25±0.43 | 4.95±0.32 | 0.580 |
| Width (posterior)-follow-up (mm) | 5.01±0.45 | 4.73±0.40 | 0.650 |
| Width (anterior)-follow-up (mm) | 4.87±0.52 | 3.88±0.34 | 0.129 |
| Mean RR width-follow-up (mm) | 4.89±0.37 | 4.48±0.28 | 0.397 |
| Mean RRR (width) (mm) | 0.36±0.14 | 0.46±0.13 | 0.605 |
#With Welch correction. Independent sample t-test. P>0.05 not significant, P≤0.05 significant, P≤0.001 highly significant. BMD: Bone mineral density, RR: Residual ridge, SD: Standard deviation, NS: Nonsupplementation, S: Supplementation
DISCUSSION
WHO has classified edentulism as a disability, and India alone has 19% elderly edentulous population. No baseline data for edentulous Indian patients has been generated thus far. Efforts made to standardize treatment outcomes and eliminate confounding factors in the study included selecting subjects with the same attitude toward management, similar extent of RRR, and same ridge relation, i.e., Class I.[4,6,40] Gutta-percha was used as a radiopaque marker because it has minimal toxicity and minimal tissue irritability and is one of the least allergenic materials.[40]
Occlusal stresses borne by the edentulous mandible are greater than the maxilla,[7,15,19] with RRR rates being calculated as four times higher for the former.[12] This may be because the hard palate also offers support for forces applied on the maxillary denture.[8] To limit the number of outcomes, and considering that mandibular resorption is more critical to the prognosis of complete dentures, it was decided to take RR measurements of the mandible only, and not of the maxilla.
Computed tomography and ultrasound are other means of density measurement. DEXA, which can be of peripheral or central type, is rapid, reliable, and most commonly used in clinical practice, being noninvasive and objective.[34,35] It may be used to measure the BMD of entire skeleton or a region of interest.[34,35] The BMD (g/cm3) is compared to two norms: healthy 25–35-year-old adults of the same sex and ethnicity (T-score) and age-matched adults (Z-score). In 1994, the WHO defined osteoporosis as a T-score 2.5 SD or more below the young adult mean at any site (spine, hip, or mid radius). A T score 2.49- 1.0 deviations below the young adult mean defines osteopenia. Normal bone density was described as a T-score ≥−1.0 deviation of the adult mean.
Three-dimensional CBCT is used in dentistry for accurate pre- and postoperative qualitative and quantitative jaw bone analysis for implant placement, assessment of bone after distraction osteogenesis, and identification of various mandibular and maxillofacial bone deformities.[37] This was used in the study for RR dimension measurement preferentially over conventional CT as the total radiation dose is reduced. Both single- and multi-slice CT scans may be used to measure RRR in edentulous and partially edentulous patients with the advantages of being painless, noninvasive, and accurate. Disadvantages include cost, radiation exposure, and risk of artifacts.[38,39] Although varying from machine to machine and scanning parameters, the radiation dose of a CBCT scan is 3–6 times that of a digital panoramic radiograph.
The study sample with a mean age of 61.5 years had a mean BMD falling in the osteopenic range [1.03 g/cm3; T-score: −1.84 – Table 1]. An Indian study with mean age of men and women as 53.6 and 57.5 years, respectively, recorded BMD values and T-scores in the normal range.[41] The difference could be because mean age of study sample was higher and subjects were edentulous in our study. The mean RR height and width for our study sample were 22.30 and 4.25 mm. A Saudi study evaluated RR height as the shortest height of the edentulous mandible on digital orthopantomogram between superior and inferior mandibular borders at fixed reference points, as described in the ACP classification.[42,43] The authors recorded mean RR height as 24.57 mm for men and 21.62 mm for women which was in rough agreement with this study.
No statistically significant effect of age on mean BMD, T-score, and RR width at baseline was seen, though RR height was found to significantly decrease with increasing age. The BMD-age correlation was against previous findings such as those reported by Tremollieres and Ribot, who found that after BMD peaks in the twenties or thirties, it gradually reduces with age.[5] The nonsignificant findings in our study may be attributed to narrow age group intervals.
Alveolar resorption is an inevitable, irreversible, and progressive phenomenon, implying a decrease in RR with increasing age (assuming an increasing duration of edentulism with increasing age).[21] Aminah et al. found a positive correlation between age and reduced mandibular bone height in accordance with the findings of our study.[22] Progressive age has been associated with depleted systemic health, nutrition intake, and BMD. No significant relationship between RR width and age was found probably because resorption first narrows the ridge and then reduces its height making it lower and broader in a cyclic fashion.[23]
The study found no correlation between baseline RR height and width values and gender at baseline. BMD and T-scores were significantly higher for males. A study by Daly et al. reported an annual diminution in BMD which was 0.5%–0.7% more in women compared to men aged 60 years and above. This can be attributed to differences in skeletal size, peak BMD values, and postmenopausal effects.[44]
A significant direct association of RR height was found with BMD and T-scores at baseline, though the relationship was insignificant for RR width. Aminah et al. established a significant correlation between the height of lower residual ridge and mandibular bone mass per unit volume (r = 0.815 with α =0.048).[22] Studies conducted by Hirai and Xi among others also reported reduced skeletal bone density as a predisposing factor for reduced height of mandible.[45,46] Alarmingly, 46% of subjects in our study were found osteopenic and 25.3% osteoporotic. Findings were in concurrence with a previous study done by the authors emphasizing need for large-scale osteoporosis management/prevention protocol implementation for the edentulous population.[47]
No effect of duration of edentulism on RR width and height at baseline could be established. A study conducted by Jagdish and Patil in 2013 on 60 edentulous subjects also showed no effect of period of edentulism on RR dimensions.[48] Kovacić et al. showed similar RR height in patients edentulous for less and more than 1 year.[49] Furthermore, patients edentulous for a greater duration of time report a decreasing rate of RRR, more so after 10 years of edentulism in the maxilla.[50]
The study showed a significant decrease in mean RR height and width, for both the supplementation and nonsupplementation groups, between baseline and 12-month appointments. There was no change in mean BMD and insignificant improvement in T-scores for both the supplementation and nonsupplementation groups between these two evaluations. This implied an insignificant effect of supplementation on bone calcium levels between baseline and the 1-year appointment. As visualized by cone-beam computed tomography, RRR (height) in 1 year was 1.30 mm for supplementation and 1.33 mm for nonsupplementation group; RRR (width) was 0.36 and 0.46 mm for the two groups, respectively. Although nonsupplementation group RRR values were higher, the difference was insignificant. In other words, 12 months of Vitamin D and calcium oral supplementation failed to register a response. Kordatzis et al. compared resorption of the posterior lower residual ridge under CDs and two-implant-supported overdentures, immediately before and 5 years after intervention, by areal measurements using differential tomography. The average reduction in height was 1.63 mm for the complete denture group and 0.69 mm for the implant overdenture group.[9]
Wical and Swoope compared the diet of patients with negligible residual bone resorption against those with severe resorption and found a positive correlation between low calcium and Ca/P levels with RRR. They suggested that these low levels appear to be contributory factors to resorption.[30]
The results of this study did not substantiate the hypothesis that alveolar ridge resorption is retarded by Calcium and Vitamin D supplementation. This was not in alignment with a study conducted by Wical and Brussee, where the test group took fixed calcium and Vitamin D oral doses daily. Changes in height and outline of the alveolar ridge between two radiographs taken at and 1 year after extraction were recorded for both the test and placebo groups. Patients receiving supplementation had 36% less mean residual bone loss than the patients in the placebo group.[31] An important difference between the Wical and Brussee study and our article was the timing of supplementation; while the former administered supplement since the time of extraction, the latter administered supplement to patients with well-healed residual ridges.
Shea et al., in their study, reviewed the role of calcium supplementation in postmenopausal women and found that calcium has an insubstantial effect on BMD. They concluded that calcium given for two or more years can reduce the rate of bone loss but does not affect fracture risk.[32] Their finding suggests that supplementation has a beneficial role if its duration is at least 2 years. On the other hand, oversupplementation of calcium has been reported to have an association with kidney stones, gastrointestinal disorders, cardiovascular disease, and prostate cancer.
Short-term oral calcium and Vitamin D supplementation was ineffective in reducing RRR and improving BMD. Investigators envisage that before rejecting the role of such supplementation in retarding RRR, future studies testing longer duration of supplementation with different formulations and dosage of Vitamin D and calcium, or stricter compliance measuring protocols, may be potentially helpful in retarding RRR. A large number of enrolled osteopenic and osteoporotic subjects could be a study limitation. Future perspective may focus on calcium and Vitamin D supplementation on subjects with normal BMD.
Through this open-label randomized study, reference mandibular RRR and RR height and width data have been created for the Indian edentulous population.
CONCLUSION
Short-term (12 months or less) oral calcium and Vitamin D supplementation could be ineffective in reducing alveolar ridge resorption rates and improving BMD.
Financial support and sponsorship
This study was funded by the Indian Council of Medical Research, New Delhi, India.
Conflicts of interest
There are no conflicts of interest.
Acknowledgment
The authors would like to acknowledge the Indian Council of Medical Research, New Delhi.
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