Journal of Dental School

Objectives This study aimed to compare the reproducibility and consistency of the World Health Organization (WHO) and Binary oral epithelial dysplasia grading systems when applied to leukoplakic lesions, the most common oral potentially malignant disorders (OPMDs).

Methods In this retrospective, cross-sectional study, clinical data and microscopic slides of 89 leukoplakia cases were reviewed. Two pathologists independently graded each sample using both WHO and Binary systems. Inter-observer agreement was evaluated using kappa statistics. The relationship between variables and the grade of dysplasia was analyzed using T-test and Chi-square test at p<0.05.

Results The mean age of cases was 53.93 ± 13.84 years, with a slight female predominance. The lesions were most commonly located on the tongue (38.2%) and buccal mucosa (37.08%). The inter-observer agreement was higher for the Binary system (kappa index= 0.62) compared to the WHO system (kappa index= 0.46). The highest agreement was observed for cellular features such as the increased number of cell nucleoli (0.74) and cell pleomorphism (0.73), while keratin pearls showed the lowest agreement (0.21).

Conclusion The Binary classification system demonstrated superior consistency and reproducibility compared to the WHO system due to fewer grading categories. However, its detailed numerical requirements and time-consuming nature may limit its widespread adoption, which is why the WHO system is more commonly used.

Objectives: This study assessed the correlation of tongue posture with dental arch characteristics in sagittal and vertical skeletal patterns using cone-beam computed tomography (CBCT).

Materials and Methods: This cross-sectional study evaluated 225 CBCT scans of sagittal Class I, II, and III patients. Class I and II groups were subdivided into high-angle, normal, and low-angle vertical subgroups. Palatal length, width, and height, maxillary width (Wmax), mandibular width (Wman), tongue posture according to the Graber’s analysis, tongue length (TGL), and tongue height (TGH) were three-dimensionally measured. Statistical analyses were conducted using one-way and two-way ANOVA, and Pearson and Spearman tests (alpha=0.05).

Results: All dental arch parameters were significantly greater in Class III, compared with Class I and II groups (P<0.05), except for) Wman, palatal length, and palatal height( . Palatal height was significantly greater in Class II and III, than Class I group (P<0.05). Wmax was lower in high-angle than low-angle, and palatal length was lower in high-angle than low-angle and normal groups (P<0.05). In Class I normal-angle patients, Wmax had a positive correlation with TGL. In Class I low-angle patients, Wmax had a moderate positive correlation with TGH.

Conclusion: Significant differences were found in Wmax and palatal length among the vertical groups. In different skeletal patterns Wmax, Wman had a low to moderate positive correlations with D4, D5, D5ʹ, TGL and TGH. Wmax in Class I was significantly lower than that in Class III; this variable in Class II was significantly lower than that in Class III

Palatal width in Class I and Class II was significantly lower than that in Class III.

Palatal height in Class I was significantly lower than that in Class II and Class III

Objectives Restoration of primary teeth have become more critical than extracting them. Composite resin materials are considered suitable materials for primary teeth restoration due to their aesthetic and acceptable performance. However, they have limitations such as polymerization shrinkage, microleakage, post-treatment sensitivity, and reduced marginal adaptation. This study evaluated the microleakage of Tokuyama Bulk flow composite and Grandiflow composite resin materials in restored primary teeth.

Methods In this in vitro study, 54 primary teeth were randomly divided into two groups. After preparing the Class II cavity in the samples and applying acid etch and bonding material, one group was allocated to the Tokuyama Bulk flow composite, and the other group was allocated to the Grandiflow composite. The amount of microleakage was determined by immersion of samples in 1% methylene blue dye and evaluation under stereomicroscope. Scores from 0 to 3 were assigned depending on the degree of dye penetration. Mann-Whitney U test was used to compare the scores in two groups at a significance level of 0.05.

Results The amount of microleakage in the Grandiflow group was significantly higher than the Tokuyama Bulk flow group (p=0.019). In the Grandiflow group, the highest microleakage score was 3 (63.0%), 2 (29.6%), and 1 (7.4%), respectively. In the Tokuyama Bulk flow group, the highest microleakage scores were 2 (55.6%), 3 (29.6%), 1 (11.1%), and 0 (3.7%), respectively.

Conclusion It can be concluded that Tokuyama Bulk flow composites have lower microleakage than the Grandiflow composite, potentially affecting the microleakage and subsequent failure of the restoration in a positive way.

Objectives Enhancing dental health and oral hygiene is essential for preventing dental caries. Recently, there has been significant interest in using natural ingredients in oral care products. This study aimed to compare the effects of herbal toothpaste containing Saqqez oleo-gum resin essential oil with Sensodyne toothpaste on the colony count of Streptococcus Mutans (S. mutans) and salivary pH levels.

Methods A randomized double-blinded clinical trial with a crossover design was conducted with 40 students aged 18-35 years who were caries-free. Initially, unstimulated saliva samples were collected to determine the baseline mutans streptococci count and salivary pH levels. In the first phase, participants were randomly divided into two groups: Group I received herbal toothpaste containing Saqqez oleo-gum resin essential oil, while Group II used Sensodyne toothpaste. After supervised tooth brushing, saliva samples were collected again to assess pH levels and S. mutans counts. Following a 72-hour washout period, the procedures were repeated with the groups switching toothpastes according to the crossover design. Data were analyzed using the Mann-Whitney U test and Wilcoxon matched pairs signed-rank test, at a significance level of p<0.05.

Results A significant reduction in the S. mutans colony count and a significant increase in salivary pH levels were observed in both groups compared to their baseline values (P<0.05). However, no significant difference was found between the efficacy of the two toothpastes (P>0.05).

Conclusion The effect of herbal toothpaste containing Saqqez essential oil on salivary pH and S. mutans level was comparable to that of commercial toothpaste evaluated in this study.

Objectives Literature has reported high caries prevalence and unmet dental treatment needs among disabled individuals. This study was carried out to assess the oral health condition of disabled students in relation to age, gender, and type of disability in Tehran, Iran.

Methods The study involved 1,170 disabled students aged 6 to 20 years, each with one or more of the following disabilities: physical retardation (PR), hearing impairment (HI), visual impairment (VI), mental retardation (MR), and autism spectrum disorder (ASD). The mean decayed, missing, and filled teeth index was used as an oral health indicator (dmft for children aged 6-12 years, and DMFT for children older than 9 years). Mann-Whitney and Kruskal-Wallis tests at significant level of 0.05 were conducted for comparisons.

Results Mental retardation (MR) was the most prevalent disability (59.4%). The decayed component constituted the largest part of the mean dmft (82%) and DMFT (75%) indices in all age groups. Girls had significantly higher DMFT scores compared to boys (P < 0.001). Among the different disabilities, children with HI had the highest dmft score (mean ± SD = 2.17 ± 2.86), while those with MR had the highest DMFT score (mean ± SD = 3.76 ± 3.83). Additionally, the caries-free ratio was significantly higher among VI students in the 9-12 years (40.5%) and older than 13 years (38.8%) age groups.

Conclusion The high prevalence of untreated dental caries, particularly among those with HI and MR, points to significant unmet treatment needs and emphasizes the importance of regular dental check-ups and access to dental care. These results underscore the critical need for improved oral health services and preventive programs tailored to the specific needs of disabled students.

Objectives Learning clinical sciences is challenging for medical students and requires a wide range of knowledge and skills in the clinical environment. There are several ways to learn, and choosing the best can be very effective in a student’s learning success. Therefore; in this study, the learning styles of postgraduate students at Shahid Beheshti Dental School were evaluated.

Methods The study was performed on 92 postgraduate students at Shahid Beheshti Dental School. The data analysis tool was the VARK questionnaire, and the data obtained were analyzed using descriptive tests. The learning styles among the gender and age groups were comprised using Chi-square (Exact test) at p<0.05.

Results Among the mentioned learning methods, the kinesthetic method had the highest frequency, followed by the auditory and visual methods. Auditory-reading-writing- kinesthetic and visual-reading-writing were the least common. Moreover, there was no significant difference between the distribution of learning styles among men and women (p = 0.67) and different age groups (p = 0.7).

Conclusion According to the results obtained from this study on the superiority of kinesthetic learning style among postgraduate dental students, it seems necessary for the educational system's officials and managers to plan appropriately for this group of learners' learning conditions to improve the quality of education.

Objectives The final phase of root canal therapy involves the obturation of the root canal system to prevent bacterial leakage and ensure successful outcomes. However, during this process, there is a risk of sealer extrusion into vital structures such as the mandibular canal, which can lead to sensory changes like paresthesia.

Case This report discussed a 40-year-old female case who presented with a crown fracture and a periapical lesion on her endodontically treated mandibular left second molar. During the retreatment, bioceramic sealer was extruded into the mandibular canal. Immediate radiographic evaluation and cone beam computed tomography confirmed the sealer’s presence within the sub-branches of the mandibular canal, though the main canal was unaffected. Conservative treatment with ibuprofen and dexamethasone resulted in pain relief and the patient did not experience any neurological deficits such as paresthesia. A 36-month follow-up revealed successful healing of the periapical lesion and absorption of the extruded sealer.

Conclusion This case highlighted the importance of precise endodontic techniques to prevent sealer extrusion and demonstrated the potential of conservative management in cases of sealer extrusion into sub-branches of inferior alveolar nerve.

“Complex problems require complex solutions” ¹ and the population's oral health is a typical –and still unresolved- complex problem. There are some reasons why oral diseases are considered as a major and complex global public health problem. Over three billion people in the world suffer from these diseases ², and their economic burden on individuals and societies is considerable ³, but the current treatment-oriented (rather than preventive) ⁴ high-technology approach has proved inefficient and has failed to address the underlying causes of these diseases as well as the existing inequalities in oral health. Even the most cited proposed models applied to understand the determinants of oral health are mostly linear and do not adequately consider the interaction of behavioral, psychological, sociological and structural factors. Thus, a fundamentally different approach is required for a ‘radical action’, i.e., a system change to reduce the burden of oral diseases. ⁵

In this commentary, we introduce “system thinking” (ST) as the required approach to address this hugely complex problem. We will start with a brief introduction to the definition and characteristics of ST. Then, we discuss how this approach might help policy makers to develop new and effective solutions for some specific problems in the dental public health domain.

 System thinking could be considered as an initiative or approach aimed at examining how things interact with each other within their respective contexts as a whole entity. ⁶  This approach has been emerged in the public health literature with impressive growth in the recent years and its implications in solving public health problems ranging from obesity to tobacco have been discussed. Public health interventions usually deal with complex issues that are multifactorial and multilevel. The recognition of such complexity has encouraged public health practitioners and researchers to experiment with systems sciences techniques to shift their focus from individual behavior changes to societal, environmental and policy interventions. ⁷ Thoughtful engagement with complexity, including capturing and understanding nonlinear cause and effect relationships, differing time scales, identification and management of unintended consequences, and transdisciplinary thinking can be regarded as the key strengths of systems approaches that could be adopted to solve public health problems.  ⁸

 Different theories and methods in ST have been designed to aid the analysis and address complex public health problems for which simple blueprint approaches have limited success. ⁹ Some tools are developed to facilitate reaching a common understanding of an issue, thus prompting further inquiry and action among a group of people. For example, “systems archetypes”, including causal loop diagrams (CLD), can help teams to understand the generic patterns of interaction that can be applicable to their “story”, rather than using the pre-existing templates. ¹⁰ CLD has the potential to promote our understanding of the broader political, institutional, and cultural contexts. It could be helpful in improving the currently accepted causality models in dentistry, which have commonly categorized determinants as structural, intermediate and proximal ones, with direct, linear and mostly unidirectional relations. ² For example, understanding the current visible trend toward cosmetic dentistry in many high-income and even middle-income countries could be seen as a typical case that requires a system-thinking approach. Reduction of the trend to only a moral or financial issue is clearly insufficient. The interaction of a series of cultural, structural, economic and psychological causes could explain over-utilization or over-provision of aesthetic dental services. However, even when analyzing the commercial determinants of dental diseases, as an emerging approach in dental public health, its interactions seem to follow the same causality approach. Therefore, a system science approach might be helpful in identifying how unhealthy commodity industries market their products, gain control over policy, and legitimize their increasing presence in public health. Thus, identification of the connection circles for dental disease causes that would otherwise be missed in more individualized behavior approaches could be achieved by using such qualitative-quantitative methods as CLDs.

 One of the concerns of health planners has been the inquiry that whether interventions shown to be effective in a research setting would be simply replicated at the large scale or in the real world. The concept of “Effectiveness Decay” contributes the ‘effective coverage’ of an intervention to contextual and operational determinants. The process of using or utilizing an intervention begins with the questions asking whether patients access care and whether and how services are administered, received and adhered to. ¹¹ Therefore, based on this concept, the real effectiveness of a community-based intervention might differ from the expected efficacy illustrated in small-scale research settings. For example, in the field of dental public health, based on a Cochrane systematic review of Fluoride Varnish (FV) application in ideal settings for clinical trials, it is suggested that this intervention can reduce the worsening of caries in the primary dentition with a prevention fraction of 37%.  However, applying FV in wider public health programs has shown a modest and nonsignificant anti-caries effect. ¹² The potential area for case loss in these interventions, or ‘node’, as a function of many concurrent forces between actors, context and structure of health systems might be discovered. ¹³

While effectiveness decay models highlight areas of deficiency requiring targeted attention, they do not reveal the underlying causes of such a decay. There are a number of other tools including network mapping, social network analyses and process mapping that are used to map out events or show how things are connected. Thus, it is possible to examine critical processes that are associated with the potential supply and demand-side determinants underlying the nodes indicated in the effectiveness decay models. ¹¹

Application of ST in designing and evaluating the system-wide upstream policies seems to be another enormously important but overlooked issue. To design system-wide policies, the emphasis would be on some kind of multi-disciplinary and multi-stakeholder involvement. It is recommended that for a collective brainstorming on the possibly system-wide effects of the proposed upstream policies, the representative of each relevant sub-system (considering the relationships and dynamics among these sub-systems) is required. ¹⁴ The current unacceptable state of global oral health is rooted not only in external factors as competing disease priorities or scarcity of resources, but also in the inadequate coalescence among oral health actors and their disconnection with the wider global health mainstream. Therefore, to improve the populations' oral health, it is highly recommended that upstream policy interventions, such as legislation, regulation and fiscal change, focus more on the involvement of stakeholders from private and public sectors in oral health and other NCDs systems, industry, non-health sectors such as education councils, mass media, etc. We then need to focus on maximizing the synergy of efforts. Involvement of a wide range of stakeholders is crucial in conceptualizing the pathway of dynamic interactions in sub-systems or building blocks of the oral health system.

Furthermore, system thinking can be beneficial for designing the methods to evaluate the implemented system-wide interventions. The emphasis in this approach is mainly upon incorporating plausibility designs such as “interrupted time-series”, which use mixed methods to provide estimates of adequacy, processes, contexts, effects and economic analyses of the interventions. They could complement and upgrade the traditional evaluation methods commonly used in health systems, i.e., probability designs such as randomized controlled trials with high internal validity but insufficient in evaluating system-wide interventions.

Finally, it is worth mentioning that while the dental public health could benefit from system thinking approach to solve its special problems, the application of the such approach is emerging slowly in the oral health sector and mostly limited to the behavioral and psychological acculturation of dental habits such as tooth brushing.  ¹⁵    The use of systems science within DPH is crucial to understanding and promoting good oral health for all, as well as to better understanding the complexity associated with the systems.