Online First

2021 : Volume 1, Issue 1

Tooth Agenesis in People with Down Syndrom

Author(s) : Emilia Severin 1 , Ruxandra Baltag 2 , George Gabriel Moldoveanu 3 and Andreea Moldoveanu 4

1 Genetics Department , Carol Davila University of Medicine and Pharmacy , Romania

2 , Profiladent Clinic , Romania

3 Department of Anesthesiology and Intensive Care , C.I. Parhon National Institute of Endocrinology , Romania

4 Department of Preventive Dentistry , Carol Davila University of Medicine and Pharmacy , Romania

Mod J Med Biol

Article Type : Research Article

Abstract

Introduction: Down syndrome people have special health care needs due to physical, medical, developmental, or cognitive conditions and require special considerations when receiving dental treatment. As a child or an adult, people with Down syndrome frequently visit a dental clinic because of the oro-dental, and craniofacial abnormalities they present. Published medical literature reported that tooth agenesis occurs more often in people with Down syndrome than in the general population. The study aims to describe and compare the prevalence of tooth agenesis, the number of missing teeth, and the type of teeth affected in a sample of 58 people confirmed with Down syndrome by cytogenetic testing.

Material and Methods: A total of 58 persons with Down syndrome needed dental care and treatment. None had previous orthodontic treatment. The dental findings were described by performing the complete extra- and intra-oral clinical examinations at Profiladent Clinic in Bucharest. For the assessment of tooth agenesis, a radiographic examination has been performed as well. All patients were able to cooperate for radiographic exams or panoramic radiographs, and no sedation was required. To select participants, we analysed medical records and cytogenetic profiles. 

Results: The prevalence of tooth agenesis among Down syndrome participants is 56.9%. Most affected individuals suffer only a mild form of tooth agenesis involving a small number of missing teeth (one or two). Some tooth types were more often missing than other ones. Excluding the third molar, upper lateral incisor and lower second premolars were most commonly missing teeth. Bilateral agenesis of upper lateral incisors occurred more often. There was no difference between the left and right sides of the jaw. Tooth agenesis occurred in different phenotypic patterns. Additional dental anomalies included microdontia, delays in development, delayed eruption, or taurodontism.

Conclusion: Down syndrome has tooth agenesis as one of its features. The severity of tooth agenesis varied from person to person. 

Keywords: Tooth Agenesis; Down’s Syndrome; Trisomy 21

Introduction

Down’s syndrome (DS) is the most common and best known of all chromosomal syndromes [1]. The aetiology of Down syndrome is trisomy of all or part of chromosome 21, especially its long arm, in all or some of the body cells. Down syndrome people have special health care needs due to physical, medical, developmental, or cognitive conditions and require special considerations when receiving dental treatment [2]. Many of the medical and physiological features of Down syndrome have direct consequences for the oral health of persons affected and indirect consequences for the quality of life of persons with Down syndrome and their carers [3]. As a child or an adult, Down syndrome people frequently visit a dental clinic because of several oral-facial abnormalities and tooth anomalies they present. These include class III malocclusion, relative macroglossia, and delayed tooth eruption, missing teeth, microdontia, taurodontism, ectopic eruption and impaction of teeth. Due to compromised immune response, people with Down syndrome have an increased risk for periodontal disease as well. Published medical literature reported that absence of tooth development occurs more often in people with Down syndrome than in the general population [4]. Tooth agenesis may increase the risk for malocclusion, masticatory dysfunction, speech disorder, or aesthetic problems. The study aims to describe and compare the prevalence of tooth agenesis, the number of missing teeth, and the type of teeth affected in a sample of 58 people confirmed with Down syndrome by cytogenetic testing. Our study contributes to the literature by presenting individual phenotypic patterns of tooth agenesis in people with trisomy 21 and not only by describing the number or type of missing teeth.

Material and Methods

A total of 58 Caucasian persons with Down syndrome (25 males and 33 females) needed dental care and treatment. To select participants, we analysed medical records and cytogenetic profiles. The participants, aged between 8-36 years, were enrolled in our study if they met the following criteria:

  1. Having one or more missing teeth (excluding the third molar).
  2. Cytogenetic diagnosis of trisomy 21.
  3. Having no previous orthodontic, restorative, or prosthodontic treatment.
  4. Adequate cooperation.
  5. Mild cardiac problems.
  6. Patients or parents/legal guardians were able to read and sign informed consent.

A 47 age and gender-matched healthy control participants have been included in the study as well. The dental findings were described by performing the complete extra and intra-oral clinical examinations at Profiladent Clinic in Bucharest. For the assessment of tooth agenesis, a radiographic examination has been performed as well. All patients were able to cooperate for radiographic exams or panoramic radiographs, and no sedation was required. The sample size was too small, and statistical analysis was not used. The Ethics Committee of the “Carol Davila” University approved the study clinical protocol.  The research was in full accordance with the World Medical Association Declaration of Helsinki. All the parents or legal guardians of the Down syndrome participants signed the informed consent form.


Results
Out of 58 subjects with Down syndrome, 33 (15 males and 18 females) experienced tooth agenesis meaning 56.9% of our patients. Tooth agenesis showed lower prevalence in the control group (4.3%) compared with the Down syndrome group. Due to an oral cavity with undersized bone structure and all permanent teeth developed, four Down syndrome participants (6.89%) presented dental crowding. 

1.    The number of missing teeth varied between 2 and 6 (hypodontia), showing mild to moderate levels of severity of the dental phenotype. The third molars were not considered. 
2.    Distribution of tooth agenesis by gender: no significant difference between the prevalence of tooth agenesis in males and females (Table 1).

 

Permanent dentition

Prevalence %

Male (n=27)

Female (n=31)

Missing teeth

15 (55.5)

18 (58.0)

 

Table 1: Distribution of tooth agenesis by gender.
3.    Tooth agenesis and type of teeth affected: upper lateral incisor (right lateral incisor) and lower second premolars (both right and left) were most commonly missing teeth. The second molars and central incisors were most rarely affected (Table 2).

 

Tooth

Central incisor

Lateral incisor

Cuspid

Canine

Second premolar

First molar

Second molar

Prevalence

0.21

0.7

0

0

0.4

0

0

 

Table 2: Distribution of tooth agenesis by the most frequent affected tooth group.
4.    Bilateral versus unilateral tooth agenesis: considering all missing teeth, a predominance of bilateral tooth agenesis was noted (Table 3).

 

Localization

Lateral incisor

Second premolar

Maxilla

Unilateral

35.71%

25%

Bilateral

50%

37.5%

Mandible

Unilateral

14.28%

25%

Bilateral

21.42%

62.5%

 

Table 3: Prevalence rate of the most affected tooth group by the pattern of symmetry in the maxillary and mandible jaws.

5.    Distribution of missing teeth over maxilla/mandible: tooth agenesis does not seem to affect the maxilla and the mandible differently (Table 4).
6.    Distribution of missing teeth over left/right sides: no significant difference between the left and right sides of the jaw has been revealed (Table 4).

 

Localization

Lateral Incisor

Second Premolar

Maxilla

Right

71.42%

50%

Left

57.14%

50%

Mandible

Right

42.85%

75%

Left

21.42%

75%

 

Table 4: Distribution of the most affected tooth group by localization in the maxillary and mandible jaws, right and left.
7.    Tooth agenesis occurred following an individual pattern of missing teeth (Figure 1-5) characterized by the different number or types of missing teeth involved and their combination.


 


Figure 1: Multiple tooth agenesis in an 8-year-old male patient with Down syndrome. (1,2,3) Examination of the dental arches reveals a mixed dentition, with a delayed tooth eruption pattern. (4) Panoramic radiograph showing the absence of both the lateral incisors in the maxillary arch and the agenesis of the lower right lateral incisor and the left central incisor. Moreover, the agenesis is associated with mesotaurodont first molars in both upper and lower arches * Position of the missing teeth.

 


Figure 2: A 28-year-old female patient with trisomy 21 presenting lower second premolars agenesis. Several dental anomalies are observed on the intraoral photos (1,2,3): upper diastema, maxillary lateral incisors microdontia, ectopic canines and spaced lower teeth. (4) Panoramic radiograph shows the absence of the lower second premolars and an agenesis diagnosis can be confirmed. * Position of the missing tooth.