Introduction
Periodontal diseases are among the most prevalent
oral conditions worldwide (1). In
Colombia, the Fourth National Oral Health Survey (ENSAB IV)
revealed that 61.8% of the population presented with periodontitis
of varying severity, although with a higher frequency of moderate
periodontitis (43.46%), followed by advanced periodontitis
(10.62%). Only 38.2% of the population was found to be free of
periodontitis, demonstrating that it is a highly prevalent oral
pathology (2).
Periodontitis is a chronic infectious and
inflammatory disease that is multifactorial and complex, affecting
the supporting and protective tissues of the teeth. In general
terms, it results from an imbalance in the immunological
interaction between the host and the subgingival biofilm (3,4). The
disruption in the uptake of vitamin D sources, due to various
endogenous and/or exogenous factors, diminishes its levels, which
may represent an indicator at the time of the diagnosis of these
types of periodontitis (5),
particularly considering that the critical physiological action of
this vitamin is to increase intestinal calcium reabsorption,
facilitate its renal absorption and promote bone mineralization.
Therefore, vitamin D deficiency may be a risk factor for the
development of gingivitis and periodontitis, highlighting the
importance of this vitamin for bone and periodontal health
(6).
The main clinical interest in vitamin D lies in the
discovery of its receptors and the expression of the enzyme
1α-hydroxylase in various tissues. This has led to the
identification of a wide range of effects of vitamin D in different
tissues and physiological processes, such as antitumor activity,
DNA repair, apoptosis control, oxidative stress, immunomodulation,
cell adhesion, metabolism and another functions. Although research
to date remains inconclusive, an association between low levels of
vitamin D and various infectious, autoimmune, chronic and oral
diseases has been suggested, linking it to periodontal health,
given that insufficient vitamin D levels have been identified in
patients with clinical attachment loss in the periodontium
(6).
Vitamin D is acquired through dietary intake and
cutaneous synthesis triggered by exposure to sunlight.
Specifically, solar radiation induces the photolytic conversion of
7-dehydrocholesterol into previtamin D3 (precholecalciferol), which
is then rapidly transformed into vitamin D3 (cholecalciferol).
Notably, excessive sun exposure does not result in vitamin D
toxicity (7,8).
Furthermore, the amount of melanin present in the
skin affects the amount of vitamin D that can be produced.
Individuals with greater amounts of melanin in the skin (those with
darker skin types) have greater protection against the sun;
however, they require a greater amount of sun exposure to
synthesize vitamin D, rendering them more likely to experience
vitamin D deficiency. Therefore, it is necessary to conduct
examinations to assess their vitamin D levels and, if required,
initiate treatment to improve vitamin D acquisition (9,10).
Several clinical trials have investigated the
association between periodontal disease and vitamin D levels. These
studies have included diverse patient populations receiving vitamin
D supplementation, either alone or in combination with calcium or
other medications. The findings suggest that vitamin D
supplementation may reduce the risk of tooth loss (11), exert a dose-dependent
anti-inflammatory effect on gingivitis (12) and inhibit pro-inflammatory
cytokines, such as IL-1, IL-6, TNF-α and IL-10-in individuals with
periodontitis (13).
Likewise, cross-sectional studies have demonstrated
an association between low concentrations of vitamin D and
periodontal disease (14,15); however, no significant association
has been found between vitamin D deficiency and age (16). The association between vitamin D
and skin phototype has also been evaluated, with findings
indicating that in the majority of subjects with dark to very dark
skin phototypes, there is a high prevalence of vitamin D
deficiency, despite high sun exposure during the summer months
(17). This suggests that the dark
skin phototype is an endogenous factor that, even in a state o
general health, may produce levels below the normal range of
vitamin D and a possible tendency for the development of
periodontitis.
Therefore, it is crucial to elucidate the
association between periodontal disease and the consequences of
vitamin D deficiency, particularly in patients with dark skin
phototypes, due to their potential susceptibility to developing
periodontal disease. Currently, to the best of our knowledge, there
are no studies available on the association between vitamin D
levels and periodontitis in patients with dark skin phototypes.
Thus, the aim of the present study was to evaluate vitamin D levels
in patients with dark skin phototypes who have been diagnosed with
periodontitis.
Subjects and methods
Study population
A descriptive cross-sectional study was conducted.
The study population consisted of a sample of 79 patients who
attended dental evaluations at a university clinic and at the Oral
Health Center-Naval Hospital of Cartagena (Cartagena, Colombia)
between September and December, 2023. Participants were included
upon signing the written informed consent agreeing to the use of
their samples in this scientific investigation and meeting the
following inclusion criteria: Individuals diagnosed with
periodontitis or gingivitis according to the 2018 periodontal
diagnosis classification (18),
with a dark skin phototype in accordance with the Fitzpatrick scale
(types III, IV and V) (19) and of
legal age.
The exclusion criteria were the following: Pregnant
or lactating women, individuals taking medications that could
affect bone and mineral metabolism; those taking multivitamins or
dietary supplements containing vitamin D; subjects with systemic
diseases or diagnosed syndromes, specifically malabsorption
syndrome, or patients with chronic diarrhea. Participants were
recruited over a of 4-month period.
Assessment of vitamin D sources and
skin phototype
To evaluate vitamin D sources and skin phototypes, a
structured questionnaire was administered. This tool gathered
information on sun exposure and the consumption of various food
groups, including dairy products, cereals, natural juices and
animal-derived protein. Additionally, the questionnaire
incorporated parameters from the Fitzpatrick scale to determine the
skin phototype of each participant. The Fitzpatrick scale is a
dermatological classification system that categorizes skin
according to color and response to ultraviolet radiation, into six
phototypes, as follows: Type I, pale white skin (extremely
sensitive skin, always burns, never tans); type II, white skin
(very sensitive skin, burns easily, tans minimally); type III,
light brown skin (sensitive skin, sometimes burns, slowly tans to
light brown); type IV, moderate brown skin (mildly sensitive, burns
minimally, always tans to moderate brown); type V, dark brown skin
(resistant skin, rarely burns, tans well); type VI, deeply
pigmented dark brown to black skin (very resistant skin, never
burns, deeply pigmented) (19).
Initial classification was based on self-assessment and
subsequently confirmed by a dermatologist at the Naval Hospital of
Cartagena.
Measurement of periodontal
indicators
Calibrated dentists evaluated the probing depth
(PD), clinical attachment level (CAL), bleeding on probing (BoP),
bone level and tooth loss due to periodontitis in the patients.
Following this examination, the periodontal status of the included
subjects was confirmed based on the following criteria: No
periodontitis: No clinical attachment loss (CAL) and no
radiographic bone loss (RBL). PD ≤3 mm, assuming there were no
pseudopockets. Subjects were further categorized according to BoP
into: Healthy periodontium (<10% BoP) and gingivitis (≥10% BoP).
Periodontitis was categorized as: Periodontitis stages I and II, PD
of 3-5 mm, mostly horizontal RBL, and no tooth loss associated with
a periodontal cause. CAL of 1-2 mm (stage I) or 3-4 mm (stage II),
with bone loss limited to the coronal third (<15% for stage I
and 15-33% for stage II). Periodontitis stages III and IV: At least
two non-adjacent sites with CAL ≥5 mm, RBL extending to the
mid-third of the root, and PD ≥6 mm. Evidence of tooth loss due
periodontal disease (4).
Measurement of vitamin D levels
Vitamin D levels in serum were measured in duplicate
using the 25OH Vitamin D Total ELISA kit (Cat. no. KAP1971,
DiaSource®; DIAsource ImmunoAssays SA). The reaction
readings on the microplates were taken at 450 nm using the
Multiskan™ GO reader (Thermo Fisher Scientific, Inc.). The
suggested values on the kit were considered for the interpretation
of the vitamin D levels of each patient, as follows: <10 ng/ml
(deficient), 10-30 ng/ml (insufficient), 30-100 ng/ml (sufficient)
and >100 ng/ml (intoxication).
Statistical analysis
A descriptive analysis was carried out, applying
measures of central tendency and dispersion (frequency, mean ±
standard deviation). Categorical associations (given small expected
cell counts) were assessed using two-sided Fisher's exact tests;
for RxC tables the Freeman-Halton extension was used (conditioning
on row/column margins). For the continuous outcome [serum 25(OH)D],
normality within each diagnosis group was evaluated with the
Shapiro-Wilk test and homogeneity of variances with Levene's test.
As the sample sizes were unequal and one group was very small
(Stage III-IV, n=3), distributional assumptions could be fragile;
therefore, a dual approach was prespecified: One-way ANOVA when
assumptions were approximately met, complemented by the
Kruskal-Wallis test as a distribution-free sensitivity analysis.
Post-hoc multiple comparisons were applied only for 25(OH)D:
Tukey's HSD following ANOVA and Dunn's test with Bonferroni
correction following Kruskal-Wallis. A two-sided α=0.05 was
adopted. A value of P<0.05 was considered to indicate a
statistically significant difference. All analyses were conducted
using IBM SPSS Statistics, v21 (IBM Corp.).
Results
A total of 79 patients who met all the inclusion
criteria were enrolled. Of these, 72 (91.1%) were male and 7 (8.9%)
were female. The average age of the patients was 33.4 years (SD ±
14.6), ranging from 18 to 75 years. As regards oral health, 8
patients (10.1%) had a healthy periodontium, 33 (41.8%) were
diagnosed with gingivitis, 35 (44.3%) with stage I-II periodontitis
and 3 (3.8%) with stage III-IV periodontitis. Some participants
reported having risk factors related to their systemic condition,
such as smoking, stress or allergies (Table I).
 | Table IFactors related to a systemic
condition. |
Table I
Factors related to a systemic
condition.
| | Yes | No | Total |
|---|
| Condition | n | (%) | n | (%) | n (%) |
|---|
| Smoker | 8 | (10.1) | 71 | (89.9) | 79(100) |
| Presence of
stress | 21 | (26.6) | 58 | (73.4) | 79(100) |
| Presence of
allergies | 11 | (13.9) | 68 | (86.1) | 79(100) |
When assessing various sources of vitamin D uptake,
such as sun exposure and the consumption of dairy products,
cereals, natural juices and animal-derived protein, no
statistically significant associations with periodontal diagnosis
were observed; the association for dairy consumption exhibited a
borderline trend (P=0.054; Table
II).
| Table IISources of vitamin D uptake in the
study participants. |
Table II
Sources of vitamin D uptake in the
study participants.
| | Periodontitis | |
|---|
| | Healthy | Gingivitis | Stage I-II | Stage III-IV | |
|---|
| | n (%) | n (%) | n (%) | n (%) | |
|---|
| Sources of vitamin D
uptake | Yes | No | Yes | No | Yes | No | Yes | No | Total | P-valuea |
|---|
| Sun exposure | 5 (62.5) | 3 (37.5) | 22 (66.7) | 11 (33.3) | 21(60) | 14(40) | 1 (33.3) | 2 (66.7) | 79(100) | 0.768 |
| Dairy
consumption | 5 (62.5) | 3 (37.5) | 32(97) | 1(3) | 30 (85.7) | 5 (14.3) | 3(100) | 0 (0) | 79(100) | 0.054 |
| Cereal
consumption | 1 (12.5) | 7 (87.5) | 19 (57.6) | 14 (42.4) | 16 (45.7) | 19 (54.3) | 1 (33.3) | 2 (66.7) | 79(100) | 0.126 |
| Natural juice
consumption | 7 (87.5) | 1 (12.5) | 27 (81.8) | 6 (18.2) | 30 (85.7) | 5 (14.3) | 3(100) | 0 (0) | 79(100) | 0.940 |
| Animal protein
consumption | 7 (87.5) | 1 (12.5) | 29 (87.9) | 4 (12.1) | 32 (91.4) | 3 (8.6) | 2 (66.7) | 1 (33.3) | 79(100) | 0.690 |
The serum levels of vitamin D ranged between 2.0 and
43.3 ng/ml, with a mean of 22.6±7.1 ng/ml. Furthermore, all
participants were categorized based on their serum vitamin D levels
into sufficient, insufficient, or deficient levels. The majority of
the patients were classified as having insufficient levels of
vitamin D (Table IIIA). Across
the periodontal diagnostic categories, serum 25(OH)D levels
differed significantly overall (ANOVA P=0.005; Kruskal-Wallis test,
P=0.00051) (Table IIIB).
Post-hoc tests [applied only to 25(OH)D] indicated lower levels in
those with stage III-IV periodontitis vs. healthy subjects (Tukey's
test, P=0.041; Dunn-Bonferroni test, P=0.014), vs. those with stage
I-II periodontitis (Dunn-Bonferroni test, P=0.034); a difference
was also observed between those with gingivitis and stage I-II
periodontitis (Dunn-Bonferroni test, P=0.026) (Table IIIC).
| Table IIISerum vitamin D levels in the study
participants. |
Table III
Serum vitamin D levels in the study
participants.
| A, Serum 25(OH)D
descriptive statistics and vitamin D categories by periodontal
diagnosis |
|---|
| Parameter | Healthy | Gingivitis | Periodontitis stage
I-II | Periodontitis stage
III-IV |
|---|
| No. of
participants | 8 | 33 | 35 | 3 |
| Min (ng/ml) | 18.8 | 4.5 | 2.0 | 13.6 |
| Max (ng/ml) | 33.8 | 43.3 | 42.0 | 14.8 |
| Mean (± SD) | 26.7±4.9 | 20.3±6.8 | 24.4±7.1 | 14.4±0.7 |
| Deficient, n (%) | 0 (0) | 1(3) | 1 (2.9) | 0 (0) |
| Insufficient, n
(%) | 5 (62.5) | 30 (90.9) | 28(80) | 3(100) |
| Sufficient, n
(%) | 3 (37.5) | 2 (6.1) | 6 (17.1) | 0 (0) |
| B, Global tests for
serum vitamin D across the periodontal diagnostic groups |
| Test | Statistic (df) | P-value |
| ANOVA (one-way) | F (3.75)=4.636 | 0.0050 |
| Kruskal-Wallis | H (3)=17.684 | 0.00051 |
| C, Pairwise
comparisons of serum vitamin D across the periodontal diagnostic
groups. |
| Comparison | Tukey's HSD | Dunn (Bonferroni
correction) |
| Healthy vs.
gingivitis | 0.086 | 0.034 |
| Healthy vs. stage
I-II periodontitis | 0.834 | 0.999 |
| Healthy vs. stage
III-IV periodontitis | 0.041 | 0.014 |
| Gingivitis vs.
stage I-II periodontitis | 0.062 | 0.026 |
| Gingivitis vs.
stage III-IV periodontitis | 0.462 | 0.645 |
| Stage I-II vs.
stage III-IV periodontitis | 0.069 | 0.034 |
Additionally, when applying the Fitzpatrick criteria
to determine skin phototype, 8 participants (10.1%) were classified
as phototype III, 54 (68.4%) as phototype IV and 17 (21.5%) as
phototype V. When these were associated with the patient groups,
phototype IV was found to be the most prevalent among those with
gingivitis and stage I-II periodontitis. Pairwise exact comparisons
of phototype distributions across the diagnostic categories
revealed differences for stage III vs. IV periodontitis (P=0.017),
stage III vs. V periodontitis (P=0.018), and stage IV vs. V
periodontitis (P<0.0001) (Table
IVA).
| Table IVComparisons of phototypes vs.
diagnoses and vitamin D status. |
Table IV
Comparisons of phototypes vs.
diagnoses and vitamin D status.
| A, Comparison of
phototypes vs. diagnoses |
|---|
| Phototype | Healthy | Gingivitis | Periodontitis I and
II | Periodontitis III
and IV | Total | P-value |
|---|
| Phototype III, n
(%) | 0 (0) | 1(3) | 6 (17.1) | 1 (33.3) | 8 (10.1) | 0.017a |
| Phototype IV, n
(%) | 4(50) | 25 (75.8) | 24 (68.6) | 1 (33.3) | 54 (68.4) | 0.018b |
| Phototype V, n
(%) | 4(50) | 7 (21.2) | 5 (14.3) | 1 (33.3) | 17 (21.5) |
<0.001c |
| Total | 8(100) | 33(100) | 35(100) | 3(100) | 79(100) | |
| B, Comparison of
phototypes vs. categories of vitamin D |
| Phototype | Deficient | Insufficient | Sufficient | Total | P-value |
| Phototype III, n
(%) | 0 (0.0) | 7 (87.5) | 1 (12.5) | 8 (100.0) | 0.999a |
| Phototype IV, n
(%) | 2 (3.7) | 45 (83.3) | 7 (13.0) | 54 (100.0) | 0.999b |
| Phototype V, n
(%) | 0 (0.0) | 14 (82.4) | 3 (17.6) | 17 (100.0) | 0.673c |
| Total | 2 (2.5) | 66 (83.5) | 11 (13.9) | 79 (100.0) | |
Similarly, phototypes III, IV and V were compared
against the vitamin D categories, no significant pairwise
differences were detected (stage III vs. IV periodontitis, P=0.999;
stage III vs. V periodontitis, P=0.999; stage IV vs. V
periodontitis, P=0.673). Notably, both individuals with deficient
vitamin D were phototype IV, and the majority of participants with
phototypes IV and V were classified as insufficient (Table IVB).
Discussion
The present study involved 79 patients, with a
notable predominance of male participants (91.1%), which may
reflect a gender disparity in the pursuit of dental care or a
higher prevalence of periodontal conditions among males. This
observation aligns with existing evidence identifying male sex as a
non-primary risk factor for the development of chronic
periodontitis (10). Moreover, the
sex distribution within the Colombian armed forces, where males
outnumber females at a ratio of ~60:1-may also explain this
imbalance (20).
The oral health status varied considerably within
the study sample, with a marked number of participants diagnosed
with gingivitis or periodontitis at various stages, indicating a
high burden of periodontal disease in this clinical setting. This
pattern is consistent with reports of a higher periodontal disease
burden among individuals with darker skin phototypes and in
populations of African origin (21), although causal inferences cannot be
drawn from our cross-sectional design. Consistent with the pairwise
analyses, phototype distributions differed across periodontal
diagnosis categories (Table
IIIB). These observations underscore the importance of tailored
periodontal care and preventive strategies.
The presence of systemic risk factors, such as
smoking, stress and allergies further illustrates the
multifactorial nature of periodontal disease and highlights the
importance of a holistic, patient-centered approach to oral health
and management.
As regards sources of vitamin D uptake, no
statistically significant associations with periodontal diagnosis
were observed; dairy intake exhibited only a borderline trend
(P=0.054; Table II). Diet remains
a plausible contributor to the vitamin D status and promoting
vitamin D-rich or fortified foods may be considered (22), particularly given the predominance
of insufficiency in our sample. Previous research has reported
inverse associations between vitamin D and periodontal disease
(23); however, the
cross-sectional design of the present study and the absence of a
direct analysis of dietary intake vs. vitamin D preclude causal
inferences. The widespread insufficiency also raises concerns about
bone integrity and immune function, both relevant to periodontal
health, and supports the need for longitudinal and interventional
studies to clarify the impact of improving vitamin D status on
periodontal outcomes (21).
Concerning skin phototype and vitamin D categories,
no statistically significant pairwise differences were detected
(Fisher's test 2x3: stage III vs. IV periodontitis, P=0.999; stage
III vs. V periodontitis, P=0.999; stage IV vs. V periodontitis,
P=0.673; Table IVB). While both
participants with deficient vitamin D levels were phototype IV,
this subgroup was very small (n=2), and the pattern should be
interpreted with caution. Given the influence of skin pigmentation
on cutaneous vitamin D synthesis, phototype remains a relevant
clinical consideration when evaluating vitamin D status and its
potential implications for oral health (22).
However, certain limitations of the present study
should be acknowledged. The relatively small sample size and the
potential for selection bias may restrict the generalizability of
the findings. Moreover, the lack of a large control group limits
the ability to draw definitive conclusions regarding the
association between vitamin D levels and periodontal disease within
this population. Future research is thus required to prioritize
longitudinal analyses for a more accurate investigation of the
association between vitamin D status, oral health outcomes and
systemic risk factors over time. Additionally, implementing
targeted interventions to improve vitamin D levels and evaluating
their effects on periodontal health could provide critical evidence
to guide clinical practice and public health strategies.
In conclusion, the majority of the participants in
the present study exhibited insufficient vitamin D levels, and
lower levels were observed in those with advanced periodontitis.
While phototype distributions varied across periodontal diagnosis
categories, the phototype was not associated with vitamin D
categories. No statistically significant associations were
identified between sources of vitamin D intake and periodontal
diagnosis (dairy intake exhibited only a borderline trend). These
findings support considering vitamin D status within periodontal
care for patients with darker phototypes and motivate longitudinal
studies, ideally with validated dietary assessment and
multivariable adjustment, to delineate causal pathways and evaluate
targeted interventions.
Acknowledgements
The authors would like to thank the Dental Service
of the Cartagena Naval Hospital (Cartagena, Colombia).
Funding
Funding: The present study was funded by the Rafael Nuñez
University Corporation.
Availability of data and materials
The data generated in the present study may be
requested from the corresponding author.
Authors' contributions
DOC performed the vitamin D quantification and data
analysis, and wrote the manuscript. JOP participated in data
analysis and in the reviewing of the manuscript. WGVS managed the
patients and performed the periodontal analysis. RP managed the
patients, performed the periodontal analysis and data management,
and was involved in the reviewing of the manuscript. RP and WGVS
confirm the authenticity of all the raw data. All authors have read
and approved the final manuscript.
Ethics approval and consent to
participate
The present study was approved by the Ethics
Committee of the Rafael Nuñez University Corporation, Cartagena,
Colombia (code CURN0605-CE052020). Participants were included upon
signing the written informed consent agreeing to the use of their
samples in this scientific investigation.
Patient consent for publication
Not applicable.
Competing interests
The authors declare that they have no competing
interests.
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