Periodontitis awareness and knowledge levels among undergraduate dental students

Abstract

Background

Dental students, as future oral healthcare providers, play a vital role in promoting periodontal health and educating the public. A solid foundational understanding of periodontitis is therefore essential. This study assessed the level of comprehension of periodontitis among dental students at Chulalongkorn University and explored factors associated with their understanding.

Methods

A cross-sectional questionnaire was administered to 425 undergraduate dental students. Responses to the open-ended question “What is periodontitis?” were qualitatively analyzed and tagged with keywords corresponding to major concepts in the American Academy of Periodontology (AAP) (e.g., gingival inflammation, attachment loss). Answers were classified as “totally correct” (TC), “partially correct” (PC), or “incorrect” (IC). Subgroup analyses were performed using the Chi-square tests.

Results

Among 425 valid responses, half of the students (50.2%) fell into the (PC) group, suggesting that many students possessed only a partial understanding of periodontitis. Clinical-year students demonstrated a significantly higher proportion of TC responses compared to pre-clinical students (p < 0.001). Mentions of attachment loss were more frequent among clinical students, consistent with greater emphasis on this core feature during clinical training. Academic year was significantly associated with correctness of responses (p < 0.001).

Conclusion

Clinical-year students more frequently included both gingival inflammation and attachment loss in their definitions of periodontitis than pre-clinical students, while partially correct responses were common and incorrect responses occurred across academic years, particularly in earlier years. The observed variation across academic years suggests that continued emphasis on core periodontal concepts throughout the curriculum may support more consistent understanding among undergraduate dental students.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-026-08054-7.

Background

Periodontal diseases, encompassing gingivitis and periodontitis, remain among the most prevalent oral health problems globally [1]. They negatively affect oral function, systemic health, and overall quality of life [2]. Despite being largely preventable through effective oral hygiene practices, their global burden continues to rise [3], reinforcing the importance of periodontal health literacy [4] and preventive strategies, especially among young adults developing lifelong health behaviors [5].

University populations represent an important demographic for periodontal health promotion, particularly among dental students who will assume central roles as future educators and clinicians [6, 7]. However, substantial gaps persist in oral health knowledge among both dental and non-dental students [8], highlighting deficits in understanding disease symptoms, prevention techniques, and treatment modalities. Prior Thai evidence shows that the general adult population has only superficial awareness of periodontitis, primarily recognizing gingival inflammation while lacking understanding of attachment loss [9].

Such deficits may affect not only students’ own oral health behaviors but also their ability to deliver accurate and effective periodontal education [10]. People frequently expect dental students, regardless of academic year, to possess comprehensive dental knowledge [11]. Despite this expectation, periodontal health knowledge has been extensively assessed in the general population [12–14] but remains insufficiently explored among undergraduate dental students.

Moreover, it is important to recognize that improving periodontal health outcomes among dental students has implications beyond individual health. Dental students are future oral healthcare providers and are often expected to explain periodontal diseases to patients. Their level of knowledge and understanding influences how periodontal concepts are presented and discussed in educational and clinical settings. This may affect how preventive measures and periodontal health information are conveyed during dental training and practice [15].

In dental education, although clinical exposure strengthens technical skills, understanding the biological basis of periodontitis, is essential for accurate diagnosis, clinical reasoning, and effective patient communication. Accordingly, evaluating how students conceptualize periodontitis, rather than focusing solely on clinical performance, offers meaningful insight into the depth and integration of their knowledge. Given that the Faculty of Dentistry, Chulalongkorn University houses the largest dental school in Thailand, it provides a representative cohort for assessing periodontal awareness. This study therefore aimed to assess the level of comprehension of periodontitis among Chulalongkorn University dental students and to identify the factors associated with variations in understanding.

Methods

Study design and ethical considerations

This observational, cross-sectional, questionnaire-based study received ethical approval from the Human Research Ethics Committee of the Faculty of Dentistry, Chulalongkorn University (HREC-DCU 2023–056) and adhered to the principles outlined in the Declaration of Helsinki. All participants provided written informed consent prior to participation.

Study population and sampling

The study population comprised Thai undergraduate dental students enrolled at the Faculty of Dentistry, Chulalongkorn University, during the 2023 academic year. Students from the 1st to 6th academic years were included and categorized into two groups based on training level: Pre-clinical group: 1st − 3rd year students and Clinical group: 4th − 6th year students. As the study aimed to include the entire population of enrolled undergraduate dental students during the 2023 academic year, a census sampling approach was adopted. All eligible students were invited to participate.

Data collection

An online questionnaire (Supplementary file 1) was developed using Google Forms and distributed via QR code. Data collection took place from October 1 and December 31, 2023, after midterm examinations and before final examinations of the first semester. At the time of data collection, 3rd year students were completing their first formal periodontology course, while 4th year students had already commenced clinical periodontology training (Supplementary Table 1). The questionnaire consisted of two sections:1) Demographic Information: age, gender, academic year, and dental visit frequency over the past 10 years, and 2) The open-ended question: Participants were asked, “What is periodontitis?”.

The wording and content of the questionnaire were drafted by periodontology faculty members to reflect core periodontal concepts in the American Academy of Periodontology (AAP) Glossary of Periodontal Terms [16] and were reviewed within the research team for clarity and alignment with the study objectives. Because the primary outcome was a qualitative categorization of open-ended responses rather than a psychometric score, formal reliability testing of questionnaire items was not applicable; instead, methodological rigor was strengthened through coder calibration and consensus procedures as described below.

Three calibrated investigators (D.A., N.R., P.I.) independently reviewed each response. Keywords were manually tagged based on content and included: gingival inflammation, gingival swelling, gingival bleeding, tooth mobility, gingival recession, calculus, malodor, other unrelated conditions (e.g., dental caries), and responses indicating uncertainty (“do not know”). Any discrepancies in coding were resolved through consensus discussion among the investigators.

Keywords were compared with definitions from the AAP Glossary of Periodontal Terms [16]. Excluding responses categorized as “do not know,” keywords were grouped into four categories: (1) gingival inflammation (gingival inflammation, gingival swelling, gingival bleeding); (2) attachment loss (tooth mobility, gingival recession); (3) conditions suggestive of periodontitis but inconsistent with the AAP definition; and (4) unrelated conditions.

Participants’ responses to the open-ended question “What is periodontitis?” were analyzed qualitatively and classified into three categories based on predefined criteria aligned with the AAP Glossary of Periodontal Terms. Responses were classified as Totally Correct (TC if they included both gingival inflammation and attachment loss (e.g., “A disease characterized by inflammation of the gums and destruction of the bone and tissues surrounding the teeth”). Partially Correct (PC) responses mentioned either gingival inflammation or attachment loss, but not both (e.g., “Diseases caused by inflammation of periodontal tissues lead to symptoms, such as swelling, redness and pain in the periodontal area”, “A disease that causes destruction of the tissues surrounding the teeth.”). Incorrect (IC) responses contained unrelated or inconsistent concepts, such as tooth-based pathology rather than periodontal disease (e.g., “It is a tooth infection that penetrates through the enamel and dentin layers, reaching the gum area”).

Data analysis

Data were analyzed using IBM SPSS software package (version 29; SPSS Inc., Chicago, IL, USA) with a significance level of p ≤ 0.05. Normality of continuous data was assessed using the Kolmogorov-Smirnov test. Descriptive statistics were presented as mean and standard deviation for normally distributed data, median for non-normally distributed variables, and frequency with percentage for categorical variables. Comparisons between pre-clinical and clinical groups, as well as associations between response categories and academic year, were examined using the Pearson Chi-square test.

Results

During the data collection period, a total of 442 dental students enrolled in the Faculty of Dentistry, Chulalongkorn University, were eligible for inclusion in the study. Of these, 434 students completed the questionnaire, yielding a response rate of 98.2%. Nine responses (2.07%) indicating uncertainty (“do not know”) were excluded, leaving 425 participants for analysis (Fig. 1). Of these, 207 (48.7%) were pre-clinical students and 218 (51.3%) were clinical students. Participants’ demographic characteristics are summarized in Table 1. Most of them were female (64.2%), and a large proportion reported regular dental visits over the past 10 years (80.9%).

Fig. 1.

Flow of data collection

Table 1.

Demographic data of the participants (N= 425)

Age (mean ± SD) (years)	21.04 ± 2.01
Demographic data	N (%)
Gender
• Woman	273 (64.2%)
• Man	152 (35.8%)
Dental visit frequency over the past 10 years
• Regularly	344 (80.9%)
• Only when having symptoms	78 (18.4%)
• Never	3 (0.7%)
Academic year
• 1st year	61 (14.4%)
• 2nd year	83 (19.5%)
• 3rd year	63 (14.8%)
• 4th year	71 (16.7%)
• 5th year	81 (19%)
• 6th year	66 (15.5%)
Educational level
• Pre-clinical year	207 (48.7%)
• Clinical year	218 (51.3%)

Analysis of open-ended responses

Participants’ answers to the question “What is periodontitis?” were analyzed and categorized using keywords aligned with the AAP Glossary of Periodontal Terms. Keywords were grouped into four main categories: gingival inflammation, attachment loss, conditions suggestive of periodontitis but inconsistent with the AAP definition, and other unrelated conditions (Table 2).

Table 2.

Keywords tagged from response of questions “What is periodontitis?”, categorized in groups based on alignment with the American Academy of Periodontology Glossary of Periodontal Terms

Gingival inflammation	Attachment loss
- Gingival inflammation	- Attachment loss
- Gingival swelling	- Tooth mobility
- Gingival bleeding	- Gingival recession
Other keywords implying periodontitis but not in AAP periodontitis definition	Other keywords not related to periodontitis
- Calculus	- Dental caries
- Malodor	- Disease in the mouth
- Plaque	- Cystic lesion
	- Tooth disease
	- Infection
	- etc.

From a total of 920 identified keywords, the two most commonly referenced concepts were: gingival inflammation (334 keywords; 36.3%) and attachment loss (436 keywords; 47.4%). Keyword distribution differed between educational levels. Pre-clinical students more frequently associated periodontitis with gingival inflammation (181 keywords; 23.2%), while clinical students more often mentioned attachment loss (215 keywords; 27.5%) (Table 3).

Table 3.

Distribution of keywords in groups categorized based on the response to the question “What is periodontitis?” and based on educational level: pre-clinical and clinical year

	Distribution of keywords in groups based on the response to the question
Keywords N = 781 (100%)	All group		TC group		PC group		IC group
	Preclinic	Clinic	Preclinic	Clinic	Preclinic	Clinic	Preclinic	Clinic
Gingival inflammation (Total = 334)	181 (23.2%)	153 (19.6%)	67	121	114	32	0	0
-Gingival inflammation	142	140	54	109	88	31	0	0
-Gingival swelling	29	5	8	5	21	0	0	0
-Gingival bleeding	10	8	5	7	5	1	0	0
Attachment loss (Total = 319)	104 (13.3%)	215 (27.5%)	67	137	37	78	0	0
- Attachment loss	55	168	33	108	22	60	0	0
- Tooth mobility	19	34	14	21	5	13	0	0
- Gingival recession	30	13	20	8	10	5	0	0
Other keywords implied to periodontitis but not in the AAP periodontitis definition (Total = 74)	19 (2.4%)	55 (7.0%)	11	28	5	23	3	4
- Calculus	8	17	4	7	3	9	1	1
- Plaque	9	35	5	19	2	13	2	3
- Malodor	2	3	2	2	0	1	0	0
Other conditions not related to periodontitis (Total = 54)	41 (5.2%)	13 (1.7%)	4	4	8	2	29	7
- Dental caries	1	0	0	0	1	0	0	0
- Disease in the mouth, cystic lesion, tooth disease, infection etc.	40	13	4	4	7	2	29	7
Total	346	436	149	290	165	135	32	11

Abbreviations: TC Totally correct, the answer with keywords related to both gingival inflammation and attachment loss, PC Partially correct, the answer with keywords associated with either gingival inflammation or attachment loss, IC Incorrect, the answer with other keywords

When classified according to correctness, 50.2% of students fell into the PC group, demonstrating partial but incomplete understanding of periodontitis, primarily identifying either gingival inflammation or attachment loss. Clinical students had a significantly higher proportion of TC responses than pre-clinical students (p < 0.001). In contrast, IC responses, reflecting fundamental misunderstandings or unrelated conditions, were more prevalent among pre-clinical students (Table 4).

Table 4.

Distribution of the participants in groups based on their response from the question “What is periodontitis?”

	Total (N = 425) Preclinic (N = 207), Clinic (N = 218)
	TC group		PC group				IC group
Number of participants; N	Preclinic	Clinic	Preclinic (N = 119) Clinic (N = 95)				Preclinic	Clinic
	57	112	Keywords related to “Gingival inflammation”		Keywords related to “Attachment loss”		31	11
			Preclinic 91	Clinic 31	Preclinic 28	Clinic 64

Abbreviations: TC Totally correct, the answer with keywords related to both gingival inflammation and attachment loss, PC  Partially correct, the answer with keywords associated with either gingival inflammation or attachment loss, IC Incorrect, the answer with other keywords

A statistically significant association was observed between correctness of responses and academic year (p < 0.001). Notably, TC responses peaked in the 3rd and 4th years, corresponding to the transition into clinical training. A slight decline in TC responses occurred in the 5th and 6th years, although overall understanding remained higher than in pre-clinical years. Detailed distributions across academic years are shown in Table 5.

Table 5.

Demographic data of participants and their association between responses the question “What is periodontitis?”

Demographic data		Group of the participants
		TC group (N= 169)	PC group (N = 214)	IC group (N = 42)	Total (N = 425)	p- value
Academic year	Year 1	11 (15.7%)	41 (58.5%)	9 (12.8%)	70 (100%)	< 0.001*
	Year 2	15 (18.1%)	50 (60.2%)	18 (21.7%)	83 (100%)
	Year 3	31 (49.2%)	28 (44.4%)	4 (6.4%)	63 (100%)
	Year 4	41 (57.7%)	24 (33.8%)	6 (8.5%)	71 (100%)
	Year 5	37 (45.7%)	40 (49.4%)	4 (4.9%)	81 (100%)
	Year 6	34 (51.5%)	31 (47.0%)	1 (1.5%)	66 (100%)
Educational level	Pre-Clinic	57 (27.5%)	119 (57.5%)	31 (15.0%)	207 (100%)	< 0.001*
	Clinic	112 (51.4%)	95 (43.6%)	11 (5.0%)	218 (100%)
Dental visit	Regularly	32(9.3%)	176(51.2%)	136(39.5%)	344 (100%)	0.389
	Only when having symptom	33(42.3%)	36(46.2%)	9(11.5%)	78 (100%)
	Never	0(0%)	2(66.7%)	1(33.3%)	3 (100%)

Abbreviations: TC  Totally correct, the answer with keywords related to both gingival inflammation and attachment loss, PC  Partially correct, the answer with keywords associated with either gingival inflammation or attachment loss, IC  Incorrect, the answer with other keywords

*Pearson Chi-square test: p- value; statistically significant at p < 0.001

Discussion

This study examined the periodontal knowledge of Thai undergraduate dental students by analyzing their open-ended definitions of periodontitis. The findings revealed clear differences between pre-clinical and clinical students, with higher accuracy generally observed among clinical-year students. However, important gaps remained, even among clinical-year students, underscoring persistent challenges in periodontal education.

Clinical students demonstrated significantly greater accuracy in defining periodontitis, frequently referencing both gingival inflammation and attachment loss, which aligns with the AAP definition [16]. In contrast, pre-clinical students tended to focus primarily on gingival inflammation, reflecting a more superficial understanding of the disease without acknowledging the essential concept of attachment loss. This observed difference may be related to differences in clinical exposure across academic years, as previous studies have reported that clinical exposure enhances students’ understanding and diagnostic accuracy regarding periodontal diseases [15]. Additionally, evidence from more experienced cohorts, including periodontists, periodontal residents, and dental interns, indicates that increased clinical exposure correlates with improved diagnostic performance, especially for attachment-loss-based criteria [17].

Interestingly, the proportion of totally correct responses peaked during the transition between pre-clinical and early clinical training (3rd and 4th years) and then declined slightly in later clinical years. This pattern may reflect reduced reinforcement of foundational periodontal knowledge as students progress into more specialized or procedure-focused clinical rotations. At the Faculty of Dentistry, Chulalongkorn University, formal didactic Periodontology courses are delivered mainly in the 3rd and 4th years (Supplementary Table 1). Reduced curriculum exposure in later years may therefore be associated with changes in conceptual recall. Similar trends have been reported in other health professions, where skill and knowledge decline without structured longitudinal reinforcement [18, 19]. In addition, peer interaction across clinical years and students’ engagement or affinity toward faculty members teaching the discipline may also influence knowledge retention and conceptual understanding. Variations in understanding may reflect the interplay of multiple educational and contextual factors rather than curriculum sequencing alone. Nevertheless, continued curricular integration, including spiral curriculum approaches or periodic reinforcement, may therefore help sustain retention of core periodontal concepts throughout training.

The higher prevalence of incorrect responses among pre-clinical students further emphasizes the importance for strengthening foundational periodontal instruction. Because Periodontology is traditionally introduced in the later pre-clinical years, students in their earlier years may form misconceptions or lack adequate baseline understanding. Prior research suggests that early introduction of core periodontal principles contributes to improved long-term comprehension, clinical reasoning, and confidence [20, 21]. Incorporating structured and progressive educational modules earlier in the curriculum, or even within pre-university health-science preparatory programs, may therefore establish a more robust conceptual foundation prior to clinical practice.

In evaluating students’ understanding, this study used the AAP Glossary of Periodontal Terms definition of periodontitis [16] as the reference. This definition emphasizes inflammation of periodontal tissues coupled with clinical attachment loss, alveolar bone loss, and periodontal pocket formation. Although the 2018 periodontal classification provides a contemporary case definition based on interdental clinical attachment loss [22], its primary purpose is to support clinical diagnosis and research rather than patient communication. Given its relative complexity [23], it is less suited for assessing whether dental students can articulate a clear and patient-friendly explanation of periodontitis. The Glossary definition, therefore, was considered more appropriate for evaluating student’s understanding in this educational context.

Despite the strengths of conducting a qualitative assessment of open-ended responses, which offers nuanced insight into students’ conceptual frameworks, several limitations must be acknowledged. The cross-sectional design prevents assessment of causality or changes over time, and the inclusion of a single institution may limit generalizability. In addition, the open-ended question was purposefully designed to elicit students’ understanding of periodontitis but was not derived from a formally validated instrument. Nevertheless, this approach allowed insight into how students articulated key periodontal concepts in their own words. The study also focused solely on periodontitis; inclusion of a parallel open-ended question on gingivitis could have provided a more comprehensive assessment across the periodontal disease spectrum. Variability in written expression may also have influenced response quality rather than understanding alone.

Future research may incorporate parallel open-ended questions addressing both gingivitis and periodontitis, along with longitudinal follow-up, to examine knowledge retention across academic years and to identify critical periods where reinforcement is most effective. Multi-institutional studies would help determine whether the observed trends are consistent across different educational settings. Further development and validation of standardized periodontal knowledge assessment tools may also support more robust evaluation and curricular planning.

Conclusions

This study describes differences in dental students’ understanding of periodontitis across academic years. Clinical-year students more frequently included both gingival inflammation and attachment loss in their definitions of periodontitis compared with pre-clinical students, while partially correct responses were common, particularly among earlier academic years. Incorrect responses, reflecting misunderstandings or unrelated concepts, were also observed, most frequently among pre-clinical students. These findings indicate variation and gaps in understanding of periodontitis within the undergraduate dental curriculum. The observed patterns suggest that continued attention to core periodontal concepts throughout training may support more consistent understanding among dental students.

Abbreviations

TC

Totally correct; the answer with keywords related to both gingival inflammation and attachment loss

PC

Partially correct; the answer with keywords associated with either gingival inflammation or attachment loss

IC

Incorrect; the answer with other keywords

AAP

American Academy of Periodontology

Authors' contributions

Pimchanok Sutthiboonyapan: Contributed to the conceptualization, methodology, formal analysis, funding acquisition and writing-original draft of the manuscript. Nirinya Raoprajong: Contributed to the data curation, investigation, analysis and final approval of manuscript. Pirada Itthipolchai: Contributed to the data curation, investigation, analysis and final approval of manuscript. Dissara Akkarasrisawad: Contributed to the data curation, investigation, analysis and final approval of manuscript. Patrika Bodhidatta: Contributed to the data curation and writing-original draft of the manuscript. Paswach Wiriyakijja: Contributed to the conceptualization, methodology, visualization and critical revision of the manuscript.

Funding

This study was supported by the Faculty Research Grant (DRF 68 − 002), Faculty of Dentistry, Chulalongkorn University to PS.

Data availability

Data available upon request from the authors.

Declarations

Ethics approval and consent to participate

This cross-sectional questionnaire-based study received ethical approval from the Faculty of Dentistry, Chulalongkorn University (HREC-DCU 2023-056) and adhered to the principles the Declaration of Helsinki. Study participants included Thai adults aged 18 years and above. Prior to participation, all individuals provided informed consent.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.