Abstract
Background
Infraocclusion is the positioning of the occlusal plane of primary molars below the normal level, which can lead to clinical problems such as occlusal disturbances and periodontal defects. There is limited information in the literature regarding the actual frequency in various populations and its association with oral health parameters. The lack of data on its clinical presentation and frequency hinders the development of evidence-based treatment protocols. Therefore, this hospital-based cross-sectional study aims to determine the proportion of infraocclusion in children presenting to a university clinic, identify clinical findings associated with infraocclusion, and assess their gingival health status.
Methods
This study was conducted between June and November 2021 at Erciyes University. The study population consisted of children aged 5–12, of both genders, attending a university clinic. A clinical and radiographic examination was performed on 3012 patients, with clinical assessment specifically aimed at identifying the presence of infraocclusion. Prevalence, tipping, overeruption, the presence of caries in the infraoccluded and the adjacent tooth, and periodontal status, midline deviation, degree of infraocclusion, were recorded by intraoral examination, and the presence of a successor and alveolar bone height were recorded by radiographic examination.
Results
The prevalence of infraocclusion was 1.3%; 50 children with 86 teeth were diagnosed as infraoccluded. The mean age value was found to be 9.75. The highest infraocclusion rate of 24.4% is observed in mandibular primary molar teeth 74, 84, and 85. In 60% of the patients, tipping of adjacent teeth towards infraoccluded teeth, overeruption in 32%, and midline deviation in 30% were detected. Alveolar bone height in the region with infraocclusion was found to be statistically significantly lower. 6. 97% of the cases had no successors. Statistical analysis indicated that the severity of infraocclusion did not significantly influence the overall periodontal health of the study participants.
Conclusion
Infraocclusion is associated with specific clinical signs, including the tipping of adjacent teeth, decreased alveolar bone height, and increased plaque accumulation. However, the severity of infraocclusion does not significantly correlate with poorer periodontal outcomes in this population. Regular screening for infraocclusion is recommended to monitor its impact on occlusal development and guide timely interventions.
Keywords: Ankylosis, Caries, Dental plaque, Infraocclusion, Infraposition
Introduction
Infraocclusion is the positioning of a tooth below the occlusal level of adjacent teeth due to a pause in alveolar bone development during the active growth period [1–3]. While these teeth are at the occlusal level when they first erupt, they cannot maintain their position over time and remain below the level of the neighboring teeth [4]. Its worldwide prevalence ranges from 1.3% to 8.9% [5–7], and no gender difference was observed [8].
Although the etiology of infraocclusion is unclear, familial transmission, local mechanical trauma, periodontal ligament disorders, local infection, chemical or thermal damage, abnormal force exerted by the tongue, disorders in complex tissue metabolism, endocrine disorders, systemic diseases, abnormal germ position, and germ deficiency can be regarded as one of the etiological factors [9].
An infraoccluded tooth causes various changes in adjacent teeth and oral tissues. Depending on the severity of the infraocclusion, these changes can be seen as an overeruption of the antagonist tooth, tipping towards the gap in the adjacent teeth, midline deviation, delayed tooth development on the affected side, reduction in arch length, open bite and crossbite, caries, and periodontal diseases. Literature established statistically significant correlations between occlusal discrepancies and periodontal parameters, including notably deeper probing depths (P < 0.0001) and worse mobility [10, 11], caused by bacterial plaque accumulation, which is an effective indicator of periodontal health [12]. Infraocclusion causes significant tilting of neighboring teeth and vertical changes in the dental arch, which could affect periodontal status. However, this could be an association rather than a definitive causal relationship, warranting further investigation.
Early diagnosis of infraocclusion is crucial to prevent potential long-term consequences, including malocclusion, periodontal issues, and difficulties maintaining adequate oral hygiene [13, 14].
This cross-sectional investigation aims to ascertain the frequency of infraocclusion in primary molar teeth in children and characterize concomitant intraoral findings. It also aims to clarify the periodontal condition of individuals with infraoccluded primary molars, as this aspect may considerably influence treatment planning and results. We hypothesize that patients with more severe infraocclusion may exhibit severe degrees of periodontal disease.
Methods
Ethical approval
Ethical consent for the study was obtained from the Erciyes University Clinical Research Ethics Committee (No:2021/389) and was conducted in accordance with the Principles of the Declaration of Helsinki. Before examinations, informed consent was obtained from parents or guardians and children.
This study comprises a sample of 3012 patients aged 5–12, in the mixed dentition phase. These patients applied to the Erciyes University Faculty of Dentistry for the first time between June and November 2021, a six-month period.
Examiner calibration
The research team consisted of two board-certified pediatric dentists and one periodontologist. The calibration, led by an external professor experienced in pediatric dentistry, involved evaluating 20 children who were not included in the study, for clinical parameters, including tipping of adjacent teeth, overeruption of antagonist teeth, caries in infraoccluded molars and neighboring teeth, midline deviation, crossbite, degree of infraocclusion, alveolar bone height, Gingival Index (GI), Plaque Index (PI), probing depth (PD), and bleeding on probing (BOP) scores. Additionally, 20 panoramic and periapical radiographs from archives were used to assess infraocclusion. Following education for calibration, the examiners’ ability to identify the presence and severity of clinical aspects in an exam setting with 40 questions was evaluated with a success rate of 90%.
Examination procedures
Intraoral examinations of the patients were performed by two dentists in the dental unit under bright light using a mirror, probe, and air-water spray, with visual examination supported by panoramic radiography obtained during the same diagnostic session. Panoramic views were utilized to evaluate the complete dental arch and check for several infraoccluded teeth or other related problems in the dentition, enabling the maximization of the benefits while adhering to the ALARA principle.
A sharp, solid percussion sound compared to symmetric teeth, radiograph showing obliteration of the periodontal ligament space, primary teeth that were 1 mm below the line passing through the occlusal level of the adjacent teeth, and those that were seen to be below the occlusal level on the radiograph were included in the study as infraocclusion [15, 16]. The inter-examiner reliability was evaluated using Cohen’s Kappa coefficient based on the assessment of 50 children, included in the study. The calculated Kappa coefficient was found to be κ = 0.98, with a 95% Confidence Interval (CI) of 0.95–1.00.
Patients with a partial eruption of first permanent molars, patients who were in infraocclusion but had a large-surface restoration on the tooth, or patients with significant loss of material in the reference teeth were excluded from the study to ensure accurate infraocclusion diagnosis based on occlusal plane assessment. Patients were selected based on the identification of at least one primary molar exhibiting infraocclusion, confirmed through clinical evaluation and radiographic analysis.
The amount of infraocclusion by intraoral evaluation was classified as follows [1, 17, 18].
Slight: the occlusal surface of the tooth with infraocclusion is between the occlusal surfaces of the adjacent teeth and the interproximal contact point.
Moderate: between the interproximal contact point and the gingival margin.
Severe: below the alveolar crest.
The presence of caries in infraoccluded and adjacent teeth was evaluated through an intraoral examination and recorded in the evaluation form according to ICDAS [19] (ICDAS 0-No, ICDAS 1–6 Yes). This study was based on specific anatomical landmarks established in a previous investigation that focused on tipping and overeruption [20]. The overeruption was assessed by examining the individual’s occlusal plane and the marginal ridges of adjacent teeth, as well as their corresponding antagonists. Tipping was evaluated by determining the angle between the projected long axis of the unopposed molar and a line perpendicular to the occlusal plane. The underlying permanent tooth germ was recorded on panoramic radiography, and diagnostic criteria for germ absence were based on the development of the tooth germ [21].
An intraoral examination and anatomical landmarks evaluated the amount of midline deviation; the glabella, the tip of the nose, the philtrum, the subnasale, and the bridge of the nose were located in the facial midline. The dentist visually defined the facial midline by aligning the landmarks and labeled the contact point between the maxillary central incisors as the dental midline. A periodontal probe and a calibrated ruler measured the horizontal distance between the two midlines.
Alveolar bone height is defined as the distance from the mandibular base to the alveolar crest along a line parallel to the long axis of the infraoccluded tooth. The MedData program (MedData Hospital Automation System, Ankara, Türkiye) was used for the measurement of alveolar bone height. The shortest distance from the alveolar crest to the inferior border of the mandible through the midpoint of the cervical mesio-distal diameter of the ankylosed deciduous tooth was measured and compared with a symmetric tooth according to Kjaer et al. [6] (Fig. 1). Patients presenting with unilateral infraocclusion were included in the alveolar bone height measurement analyses.
Fig. 1.
Alveolar bone height measurement
The status of the periodontal tissues, including the Gingival Index (GI) (Löe&Silness 1963) [22], Plaque Index (PI) (Silness&Löe 1964), probing depth (PD) [23], and bleeding on probing (BOP) [24] (Yes/No) was evaluated. A symmetrical control tooth without infraocclusion was used as a reference in the intra-individual assessment approach.
Statistical method
Data were analyzed with IBM SPSS V23. Conformity to normal distribution was evaluated with the Shapiro-Wilk test. A paired Two-Sample t-test was used to compare normally distributed data in two dependent groups. Comparisons on categorical data were made with the Pearson Chi-Square Test, and multiple comparisons were made with the Bonferroni Corrected Z Test. Analysis results were presented as mean ± standard deviation and median (minimum–maximum) for quantitative data, and frequency (percent) for categorical variables.
Results
Of the 3012 children examined, 86 teeth were found to have infraocclusion in 50 children who were found to have infraocclusion in their primary teeth and met the inclusion criteria. (Table 1) The prevalence of infraocclusion was 1.3% among the patients examined. 58% of the participants were male, and 42% were female; 86% did not have systemic disease. The mean age of the cases included in the study was 9.75 ± 1.91 years, with an age range of 5.2–14. Twenty-one (42%) of the cases were female, and 29 (58%) were male (Table 1).
Table 1.
Presentation of frequency and percentage distributions for categorical data (Children n = 50)
| Age | Mean ± SD | Median (Min-Mak) |
|---|---|---|
| 9.75 ± 1.91 | 9.4 (5.2–14) | |
| Frequency (n) | Percent (%) | |
| Gender | ||
| Female | 21 | 42.0 |
| Male | 29 | 58.0 |
| Location of Dental Arch* | ||
| Mandible | 48 | 96.0 |
| Maxillae | 2 | 4 |
| Area | ||
| Posterior | 50 | 100.0 |
| Tooth No. | ||
| 54 | 1 | 1.2 |
| 55 | 1 | 1.2 |
| 64 | 2 | 2.3 |
| 74 | 21 | 24.4 |
| 75 | 19 | 22.1 |
| 84 | 21 | 24.4 |
| 85 | 21 | 24.4 |
| Patients with Tipping of Adjacent Teeth | ||
| No | 20 | 40.0 |
| Yes | 30 | 60.0 |
| Patient with Overeruption of Antagonist Teeth | ||
| No | 28 | 56.0 |
| Yes | 16 | 32.0 |
| Tooth extracted | 6 | 12.0 |
| Patient with Caries in Neighboring Teeth | ||
| No | 25 | 50.0 |
| Yes | 25 | 50.0 |
| Midline Deviation | ||
| No | 35 | 70.0 |
| Yes | 15 | 30.0 |
| Midline deviation measurement | ||
| 1 mm | 10 | 66.7 |
| 2 mm | 3 | 20.0 |
| 3 mm | 1 | 6.7 |
| 4 mm | 1 | 6.7 |
| Successor (Patient) | ||
| No | 5 | 10.0 |
| Yes | 45 | 90.0 |
| Systematic Disease | ||
| No | 43 | 86.0 |
| Yes | 7 | 14.0 |
*Multi-response
The tooth with infraocclusion is 96% in the mandible and 100% in the posterior region. Considering the distribution of tooth numbers, the highest rate of infraocclusion belongs to teeth 74, 84, and 85, with 24.4%. (Table 1) The lowest infraocclusion rate was 1.2% in teeth 54 and 55.
In 60% of the patients, tipping towards the infraoccluded teeth was detected in the adjacent teeth. Overeruption of the antagonist of infraoccluded teeth was seen in 32% of patients. A deficiency of the permanent tooth germ was detected in 10% of the patients. While deviation from the midline occurred in 30% of the patients, the deviation rate was 1 mm in 66.7% of those patients. Slight infraocclusion in 50% of primary teeth with germ deficiency in the mandible, severe infraocclusion in 33.33%, and moderate infraocclusion in 16.67% was observed. (Table 1)
The caries rate was found to be 52.3% in the infraoccluded tooth. (Table 2) Considering the degrees of infraocclusion according to tooth number, a slight infraocclusion degree was observed in tooth 75 at the highest rate of 63.2% (Table 2). A moderate degree of infraocclusion was observed in tooth 84 at a rate of 38.1%. Severe infraocclusal degree was observed in the right maxillary upper second primary molar with a rate of 100%.
Table 2.
Distribution of categorical data according to tooth numbers
| Tooth No. | ||||||||
|---|---|---|---|---|---|---|---|---|
| 54 | 55 | 64 | 74 | 75 | 84 | 85 | Total | |
| Degree of Infraocclusion | ||||||||
| Slight | 0 (0) | 0 (0) | 0 (0) | 13(61.9) | 12(63.2) | 12(57.1) | 11(52.4) | 48 (55.8) |
| Moderate | 1(100) | 0 (0) | 2(100) | 7 (33.3) | 6 (31.6) | 8 (38.1) | 6 (28.6) | 30 (34.9) |
| Severe | 0 (0) | 1 (100) | 0 (0) | 1 (4.8) | 1 (5.3) | 1 (4.8) | 4 (19) | 8 (9.3) |
| Caries in the Tooth | ||||||||
| Yes | 1 (100) | 1 (100) | 1 (50) | 11(52.4) | 9 (47.4) | 10(47.6) | 12 (57.1) | 45 (52.3) |
| No | 0 (0) | 0 (0) | 1 (50) | 10(47.6) | 10 (52.6) | 11(52.4) | 9 (42.9) | 41 (47.7) |
| Deciduous Teeth with Successor | ||||||||
| Yes | 1(100) | 0 (0) | 2(100) | 21 (100) | 15 (78.9) | 21 (100) | 20 (95.3) | 80 (93.03) |
| No | 0 (0) | 1(100) | 0 (0) | 0 (0) | 4 (21.1) | 0 (0) | 1 (4.7) | 6(6.97) |
Frequency (percent) No comparison was made because frequency distributions were not suitable for comparison
A statistically significant difference was found between the distributions of the degree of infraocclusion by gender (p = 0.043). While the rate of women with severe infraocclusion was 18.2%, this rate was 3.8% in men. (Table 3)
Table 3.
Distribution of tooth number and infraocclusion degree by gender
| Gender | Test Statistic | p-value | |||
|---|---|---|---|---|---|
| Female | Male | Total | |||
| Tooth No. | |||||
| 54 | 0 (0) | 1 (1,9) | 1 (1.2) | N/A | N/A |
| 55 | 1 (3) | 0 (0) | 1 (1.2) | ||
| 64 | 0 (0) | 2 (3,8) | 2 (2.3) | ||
| 74 | 8 (24.2) | 13 (24.5) | 21 (24.4) | ||
| 75 | 8 (24.2) | 11 (20.8) | 19 (22.1) | ||
| 84 | 8 (24.2) | 13 (24.5) | 21 (24.4) | ||
| 85 | 8 (24.2) | 13 (24.5) | 21 (24.4) | ||
| Degree of infraocclusion | |||||
| Slight | 19 (57.6)a | 29 (54.7)a | 48 (55.8) | 6.307 | 0.043* |
| Moderate | 8 (24.2)a | 22 (41.5)a | 30 (34.9) | ||
| Severe | 6 (18.2)a | 2 (3.8)b | 8 (9.3) | ||
*Pearson Chi-Square Test; a-b: There is no difference between ratios with the same letter.; N/A: Insufficient sample size for statistical analysis
A statistically significant difference was found between the mean values of alveolar bone height compared to the infraocluded and control sides (p = 0.001). (Table 4)
Table 4.
Descriptive statistics for alveolar bone height measurements
| Infraoccluded Side | Control Side | Mean Difference (Control- Infraoccluded Side) | Test Statistic | p-value | Effect Sizex (95% CI) |
|---|---|---|---|---|---|
| 2.21 ± 0.34 | 2.41 ± 0.23 | 0.20 ± 0.28 | -3.847 | 0.001* | -0.702 [-1.430, 0.04] |
* Paired Two Sample t-test; Mean ± S. Deviation; xCohen’s d
The median GI value was obtained as two on the side of the infraoccluded and symmetrical tooth, and the GI value did not show a significant difference (p = 0.083). There was a statistically significant difference (p = 0.013) between the median PI values on the mesial side and the symmetrical distal side. While the PI median value on the left side of the ankle was 2, it was found to be 1 on the symmetrical tooth side. There was a statistically significant difference (p = 0.013) between the median values of PD mm on the lingual side and the symmetrical tooth side. While the median value of PD mm on the lingual side is 2, this value is obtained as 1 on the symmetrical tooth side (Table 5).
Table 5.
Comparison of GI, PI, and PD mm parameters in infraocclusion side and symmetrical teeth
| Infraocclusion Side | Symmetrical Tooth | Test Statistic | p-value* | Effect Sizex (95% CI) | |
|---|---|---|---|---|---|
| Median (Min. - Max.) | Median (Min. - Max.) | ||||
| GI | 2 (0–3) | 2 (0–3) | -1.732 | 0.083 | 0.535;[-0.060, 1.130] |
| PI | 2 (0–3) | 1 (0–3) | -2.496 | 0.013 | 0.802 [0.190, 1.410] |
| PD mm | 2 (0–3) | 1 (0–3) | -2.496 | 0.013 | 0,802 [0.190, 1.410] |
*Wilcoxon Test; xCohen’s d
There was no statistically significant difference between the GI score median values according to the degree of infraocclusion (p = 0.387) (Table 6). The median GI value was 2 in mild cases, 2 in moderate cases, and 1 in severe cases. There was no statistically significant difference between the PI score median values according to the degree of infraocclusion (p = 0.662). The median PI value was 2 in mild cases, 2 in moderate cases, and 1 in severe cases. There was no statistically significant difference between the median PD mm values according to the degree of infraocclusion (p = 0.477). The median PD mm value was 2 in mild cases, 2 in moderate cases, and 1 in severe cases. BOP distributions on the infra-occluded and symmetric sides did not show a statistically significant difference (p = 1.000).
Table 6.
Comparison of GI, PI, and PD values on the infraoccluded teeth side according to the degree of infraocclusion
| Degree of Infraocclusion | ||||||
|---|---|---|---|---|---|---|
| Infraocclusion Side | Slight | Moderate | Severe | Test Statistic | p-value* | Effect Sizex (95% CI) |
| Median (Min. - Max.) | Median (Min. - Max.) | Median (Min. - Max.) | ||||
| GI | 2 (0–3) | 2 (0–3) | 1 (1–3) | 1.900 | 0.387 | 0.092 [-0.460, 0.650] |
| PI | 2 (1–2) | 2 (0–3) | 1 (1–3) | 0.825 | 0.662 | 0.320[-0.240, 0.880] |
| PD mm | 2 (0–3) | 2 (1–3) | 1 (1–2) | 1.481 | 0.477 | 0.211[-0.350, 0.770] |
*Kruskal-Wallis Test;x Cohen’s d
Of the seven patients who reported having a systemic disease, allergies accounted for 42.8% of cases, asthma for 28.5%, combined immunodeficiency for 14.2%, and hyperactivity disorder for 14.2%.
The examined parameters, the existence of an underlying germ and the arch site of infraocclusion, did not demonstrate a statistically significant impact on the extent of infraocclusion. (Tables 7 and 8) This suggests that, in the context of this investigation, these criteria were not deemed essential in assessing the severity of infraocclusion.
Table 7.
Comparison between the underlying germ and the degree of ankylosis
| Tooth germ | Total | Test Statistics | p | ||
|---|---|---|---|---|---|
| No(absent) | Yes | ||||
| Degree of ankylosis | |||||
| Slight | 2 (40) | 19 (42.2) | 21 (42) | 2.646 | 0.266* |
| Moderate | 1 (20) | 20 (44.4) | 21 (42) | ||
| Severe | 2 (40) | 6 (13.3) | 8 (16) | ||
*Pearson Chi-Square Test; Frequency (percentage)
Table 8.
Comparison between the arch location and the degree of ankylosis
| Arch location | Total | Test Statistics | p | ||
|---|---|---|---|---|---|
| Mandibul | Maxilla | ||||
| Degree of ankylosis | |||||
| Slight | 21 (43.8) | 0 (0) | 21 (42) | 4.814 | 0.307* |
| Moderate | 20 (41.7) | 2 (66.7) | 21 (42) | ||
| Severe | 7 (14.6) | 1 (33.3) | 8 (16) | ||
*Pearson Chi-Square Test; Frequency (percentage)
Discussion
This study was conducted to determine the prevalence of infraocclusion and associated oral changes in children presenting to the clinic. 50 out of the 3012 individuals who were evaluated had infraocclusion in at least one tooth. The prevalence of infraocclusion was found to be 1.3%. This rate is lower than in other studies [25–29]. Our investigation revealed a higher incidence of infraocclusion (58%) in male patients, contrary to some previous reports [26–28]. Similarly, in the study of Çiftçi et al. [30], the infraocclusion rate was higher in male patients, but this difference was not statistically significant.
Infraocclusion was more common in mandibular teeth (96%) than in maxillary teeth (6%), and all teeth were detected in the posterior region. Similarly, the incidence of infraocclusion in the posterior region and mandibular arch is higher in the literature [26–28, 30–33]. Infraocclusion occurs more frequently in mandibular molars than in maxillary molars. Numerous investigations have yielded consistent results [4, 34]. The literature has not elucidated any underlying mechanism. The exact biomechanical mechanisms remain incompletely understood; nevertheless, data clearly indicate a developmental beginning with a potential genetic predisposition. Additional work is necessary to clearly identify the anatomical or physiological changes that account for this notable disparity in prevalence [35].
The literature presents differing views on which tooth is most commonly affected by infraocclusion [25, 31, 36]. In our study, infraocclusion was observed most frequently in teeth 74, 84, and 85, while the lowest rate was seen in teeth 54 and 55. Additionally, no infraocclusion was detected in tooth 65 for the included patients.
In our study, the slightest infraocclusion was detected with a rate of 55.8%. Shalish et al. [36] detected mid-level infraocclusion most. While there was no difference between the genders at the slight and moderate levels, severe infraocclusion was significantly higher in women than in men. This result may be the subject of future research on hormone balance studies.
Since the tooth in the infraocclusion is positioned lower than the occlusal level of the adjacent teeth, it causes tooth tipping and related loss of space [13, 30, 31, 37, 38]. Becker et al. [38] found that the rotation center of the teeth adjacent to the infraoccluded tooth was located in a coronal structure. The apex of these teeth moved away from the infraoccluded tooth, and their crowns were tipped towards the infraoccluded tooth. Our study observed that in most of the patients, the adjacent teeth were tipped over the infraoccluded tooth. Future research on patients without caries would be more instructive in understanding the reasons for this movement.
Becker et al. [14] examined the position of the midline relative to the anterior nasal spine on panoramic radiography in patients with infraocclusion of mandibular primary molars. They observed a deviation from the midline in 88.2% of these patients, with a mean deviation of 2.32 mm. In our study, midline deviation was observed in 30% of the patients, with 66.7% of these cases showing a deviation of 1 mm. Infraocclusion significantly affects mandibular growth patterns, causing anterior growth rotation of the mandible [14, 39].
Kurol et al. [13] reported in their study that they detected anomalies, such as overeruption and crossbite in the occlusion, which were resolved spontaneously with the eruption of the permanent teeth. In our research, overeruption was observed in 32% of the children; however, the clinical course is unknown due to a lack of follow-up.
The reasons for increased plaque accumulation in infraocclusion cases might include the tooth’s lower positioning and the angling or overturning of adjacent teeth. Due to plaque accumulation and difficulty in maintaining oral hygiene, dental caries can also be observed in the affected tooth and adjacent teeth [30, 31, 40]. In our study, the rate of caries in the tooth with infraocclusion was 52.3%. The rate of patients with caries in their adjacent teeth was 50%. It is challenging to precisely define the relationship between infraocclusion and caries due to the widespread detection of caries in the mouth and the low level of oral hygiene habits, which is a limitation of this study.
Infraoccluded deciduous teeth are associated with increased susceptibility to periodontal disease [16, 41] and are mainly caused by food impaction in kids with poor oral hygiene [42]. This study revealed higher PI scores on infraoccluded teeth (p = 0.013). No relationship was shown between the degree of infraocclusion and PI, GI, PD, and BOP scores, which refutes our hypothesis linking severity and periodontal diseases.
The relationship between infraocclusion and congenital deficiency of the permanent tooth germ has been emphasized in previous studies [4, 25, 27, 31, 33, 36]. Congenital tooth deficiency was detected in 10% of the patients with infraoclussion included in our study. Congenital tooth deficiency was determined in 3.8% of the patients in the study by Silva et al. [26], 25% of the patients by Shalish et al. [31], and 21.7% of patients by Çiftçi et al. [30]. In another study conducted by Shalish et al. [36], premolar teeth were found to be congenitally missing in 20.2% of the patients. A congenital deficiency was detected in 6.97% of the included 86 teeth; the tooth most commonly missing was the mandibular second premolar.
In the literature, it has been shown that bone development is adversely affected in the region of infraocclusion [6, 13, 43]. Similar to previous results, in our study, alveolar height was significantly lower on the side affected by infraocclusion compared to the control side. This may affect occlusal development and tooth alignment in patients with infraocclusion. The statistically significant decrease in alveolar bone height in the infraoccluded area indicates a possible effect on long-term periodontal stability and may affect future orthodontic treatment strategies.
It is important to note that infraoccluded teeth had much higher Plaque Index (PI) scores (p = 0.013) and lower alveolar bone height (p = 0.001) than symmetrical control teeth. However, our main hypothesis that the severity of infraocclusion would be directly related to worse overall periodontal outcomes was not supported in this group of people. There were probably a number of reasons why this occurred. Our study cohort is relatively young (5–12 years), which makes them less likely to have advanced periodontal disease, regardless of the severity of infraocclusion, as these conditions typically develop and worsen over longer periods of time. Also, there were only 8 severe infraocclusion cases (9.3% of infraoccluded teeth), which probably made it harder to find a strong link between severity and periodontal parameters. Consequently, while infraocclusion clearly acts as a local risk factor for plaque accumulation and bone loss, its direct linear relationship with the severity of periodontal disease was not evident in our young study cohort.
Infraocclusion has been associated with congenital syphilis and endocrine conditions that affect the balance of bone formation and destruction [40]. Although 14% of the patients in our study had a systemic disease, these conditions were not believed to cause infraocclusion, as they did not impact bone remodeling metabolism.
This study evaluated the prevalence of infraocclusion and intraoral changes caused by infraocclusion in patients who visited the faculty clinic. The prevalence may have been underestimated due to zone limitations, which could have introduced selection bias if certain demographic groups, such as those with limited access to dental care, were underrepresented. Patients with partially erupted first permanent molars, extensive surface restorations, or significant loss of tooth material were excluded to ensure an accurate assessment of infraocclusion, which could also limit participation. The exclusion of patients with partially erupted first permanent molars and extensive restorations may have underestimated the true prevalence of infraocclusion and introduced selection bias, as these cases could still exhibit infraocclusion. This limits the generalizability of the prevalence findings to the broader pediatric population. There was no significant difference in GI, PI, PD, or BOP between degrees of infraocclusion. Therefore, the hypothesis that would have predicted greater periodontal disease in patients with more severe infraocclusion was not confirmed. The PI values indicating accumulation were higher than those of the control. There was a minimal sample size for cases of severe infraocclusion (n = 8 or 9.3% of infraoccluded teeth). The age range of the study population—from 5 to 12 years—was such that most children do not yet have conditions associated with severe periodontal disease, as they have not been exposed to various risk factors related to plaque for long periods. Other confounding factors that may have contributed to oral hygiene were not systematically recorded in this study. For instance, children with good oral hygiene may reduce the effects of periodontal disease on their tissues, whether or not they have severe infraocclusion. The above results indicate that, although it may lead to localized plaque accumulation—increasing PI and PD scores on the side of its occurrence—infraocclusion severity has no positive correlation with worse periodontal outcomes among this population. This relationship should be further assessed using large samples of cases with severe infraocclusion and comprehensive periodontal assessments.
Using a more sensitive imaging modality in future research, such as cone-beam computerized tomography (CBCT), differences in bone architecture or changes in the periodontium that are not visible clinically or on panoramic radiographs can be detected. Future research should focus on investigating the genetic and environmental determinants of infraocclusion, as well as assessing the efficacy of various therapeutic strategies in preventing its development and related consequences. Moreover, we recognize that the inclusion of patients with specific systemic conditions, despite thorough clinical evaluation, constitutes a potential limitation of this study. This suggests that future research with larger cohorts should employ more stringent subgroup analyses or exclusion criteria to comprehensively investigate the potential effects of infraocclusion on periodontal health. Oral Health–Related Quality of Life (OHRQoL) in children with infraocclusion would be a valuable avenue for future research.
Conclusion
Infraocclusion caused numerous changes in the mouth, resulting in a pause in alveolar bone height and midline deviation, which can lead to orthodontic anomalies and could be identified as a significant issue in this study. Localized plaque deposition was another notable observation. The observed lack of significant correlation between infraocclusion severity and periodontal health may be attributed to the early age of the study participants and potential confounding variables related to oral hygiene. It is crucial to raise awareness and diagnose it as early as possible to assess follow-up or treatment options with the appropriate indications.
Acknowledgements
We would like to thank the Proofreading & Editing Office of the Dean for Research at Erciyes University for copyediting and proofreading service for this manuscript.
Abbreviations
- GI
Gingival index
- PI
Plaque index
- PD
Probing depth
- BOP
Bleeding on probing
Authors’ contributions
İD and ZAG designed the study, İD, CBD, and ZAG conducted the clinical experiment and survey, ZAG and CBD analyzed the data, and İD, ZAG, and CBD wrote the paper. İD, ZAG, and CBD have approved the submitted version.
Funding
No funding was obtained for this study.
Data availability
The data that support the findings of this study are available from Erciyes University and the Ministry of Health, but restrictions apply to the availability of these data, which were used under license for the current study, and so are not publicly available. Data are, however, available from the authors upon reasonable request and with permission of Erciyes University and the Ministry of Health. The author can share data concerning clinical ethics guidelines when required.
Declarations
Ethics approval and consent to participate
The study was approved by the Erciyes University Clinical Research Ethics Committee (2021/389) and performed in accordance with the ethical standards laid down in the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards.
Consent for publication
Was given by a parent or guardian and the children. Parents and children filled out the consent form themselves. The consent form was approved by the Erciyes University Clinical Research Ethics Committee.
Competing interests
The authors declare no competing interests.
Footnotes
Publisher’s note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Data Availability Statement
The data that support the findings of this study are available from Erciyes University and the Ministry of Health, but restrictions apply to the availability of these data, which were used under license for the current study, and so are not publicly available. Data are, however, available from the authors upon reasonable request and with permission of Erciyes University and the Ministry of Health. The author can share data concerning clinical ethics guidelines when required.