A Rare Case of Bilateral Agenesis of Central Lower Incisors Associated With Upper Impacted Canine- A Case Report.

This case of a female patient, 14 yr old with association of the two anomalies, which we came across with in 2014, is rarely met in the specialty practice. The impacted canines are part of the group of dental anomalies of position, while the agenesis is part of the group of dental number anomalies. The orthodontic treatment in the two arches has to be differentiated, the therapeutic objectives being, also different in the two arches.

Introduction

The development of the dental-maxillary device represents a long and complex process, in which can appear different abnormalities from normal, variable regarding the way they are produced, the manifestations, the moment of appearance and the consequences (1).

The dental anomalies represent a special group of the dental-maxillary anomalies, in this category being included affection with a common characteristic: the dominant modification is that of the dental system, while the modification of the bone is discreet, sometimes hardly perceivable, and sometimes secondary to the dental disturbances (2, 3).

The dental anomalies can appear as freestanding, namely isolated dental anomalies, and in the orthodontic syndromes (4).

Agenesis of bilateral (both right and left) mandibular central incisors is not well documented and literature shows paucity of data pertaining to this anomaly. The first report of congenitally missing two mandibular incisors was earlier (5).

The prevalence of agenesia in European populations is estimated at 0.08% (6). Females have shown higher predilection then males (7). Certain discrete malpositions of the human canine tooth and agenesis of at least one tooth are abnormalities known to occur together, one of the situations being the association between agenesia with palatal displaced canine (8).

Depending on research, it is estimated that on average there is a 1.6% incidence of maxillary impacted canines (9). Impactions are twice as common in females (1.17%) as in males (0.51%) (9). In patients who present with impacted maxillary canines, it is estimated that 8% of these are bilateral (9). Reasons for impactions can be varied and are categorized as both localized and generalized. The most common reasons for canine impaction are usually localized and are the result of any one or combination of the following factors: tooth size/arch length discrepancies, prolonged retention, or early loss of the deciduous canine, abnormal position of the tooth bud, the presence of an alveolar cleft, ankylosis, cystic or neoplastic formation, dilacerations of the root, iatrogenic origin, and idiopathic condition. Irradiation, febrile diseases, and endocrine deficiencies are some of the general causes (9).

The aim of the present article is to report a rarely case of bilateral agenesis of central lower incisors, associated with upper impacted canine. The documentation of such case reports is necessary due to its rarity, to provide a review to minimize the clinicians challenge in diagnosing such cases and thus helpful in providing a multidisciplinary approach in treating the patient.

Possibilities of treatment in this type of dental anomalies are multiple, from orthodontic, through prosthetic, till implants, depending on many factors, age of patient being the most important in our opinion. This kind of anomalies does not have typical treatment, the choice of choosing orthodontic, prosthetic or implant treatment relies only on clinician`s decision in order to obtain the best results possible.

Case presentation

The female patient, 14 yr old in 2014, comes for an orthodontic consultation, being brought by the mother, displeased with the physiognomic aspect of her teenage daughter.

At the clinical examination are observed the following (Fig. 1):

Fig. 1:

Initial clinical aspect

-on the upper arch is found the persistence of both temporary canines and of the second temporary molars, over the physiological limit of replacing.

-on the inferior arch is found the presence on the arch of both temporary inferior central incisors, more over the physiological limit of replacing.

Orthopantomography (Fig. 2) and CBCT (Fig. 3) underlines:

Fig. 2:

Aspect of orthopantomography

Fig. 3:

Aspects of Cone Beam Computer Tomography (CBCT)

-intra-maxillary presence of germs 1.7, 1.5, 1.3, 2.3, 2.5, 2.7

-intra-maxillary presence of germs 3.8 and 4.8, in process of mineralization

-intra-maxillary absence of germs 3.1 and 4.1

Following the clinical examination, carefully studied, the analysis of the study models, the beginning photos, orthopantomography (OPT) and CBCT, we gave the diagnosis of bilateral agenesis of inferior central incisors and the diagnosis of impacted right upper canine.

The diagnosis of bilateral agenesis of inferior central incisors was given based on the radiologic examination: the intra-maxillary absence of the inferior central incisors germs, more over the physiological limit of the replacing period (10–12).

The diagnosis of impacted right upper canine was given based on the radiologic examination: the intra-maxillary presence of the germ of 1.3, with the root completely formed and the apex closed, 2 years over the maximum age of the physiological replacing (13–15).

The treatment of the two aches was differentiated, the therapeutic objectives being different in the two arches, thus:

-In the inferior arch, after the extraction of the two temporary inferior central incisors, will be chosen the closing of the distance by physiological mesializations (16–19).

-In the upper arch, after the extraction of all the temporary teeth persistent on the arch over the physiological limit of replacing, we will wait a period of a few months for the spontaneous eruption of the definitive teeth on the arch and in case of 1.3 we will choose its surgical exposing and bringing it on the arch by the slow tractioning, to a fixed poly-aggregate orthodontic appliance (20, 21).

Thus were performed dental extractions of 5.5, 5.3, 6.3 and 6.5 in the upper arch and of 7.1 and 8.1 in the inferior arch.

It followed then the applying of a fixed poly-aggregate bimaxillary metallic appliance (Fig. 4–6).

Fig. 4:

Final aspect of inferior arch

Fig. 6:

Aspect of upper arch after 4 months

Aspect of upper arch after 2 months

Discussions

The exact etiology of congenital agenesis of both central incisors is unknown, several factors like trauma, radiations, infection, metabolic disorders and idiopathic are the possible etiologic factors (22). Newman has given four main theories mainly for the cause of agenesis of incisors (23). Heredity or familial distribution is the primary cause. Second, anomalies in the development of the mandibular symphisys may affect the dental tissue forming the tooth buds of the lower incisors (24). Third, a reduction of the dentition regarded as nature’s attempt to fit the shortened dental arches (an expression of the evolutionary trend) (25) and finally, localized inflammation or infections in the jaw and disturbance of the endocrine system destroying the tooth buds (5,7).

Genes MSX1, TGFA and PAX9 interaction sometimes play a role in human tooth agenesia (26).Mandibular incisor agenesis has a large effect on mandibular symphysis growth and morphology. Buschang demonstrated that, vertical and horizontal growth changes during childhood and puberty were most pronounced in the upper half of the mandibular symphysis, resulting in an increase in the height of the mandibular body (27). Hence patients with absence of mandibular both central incisors, exhibit significantly smaller mandibular symphysis area than the normal patients. They have also reported that, the growth of alveolar bone is also associated with continuous eruption of the dentition (27). Endo M. have concluded from their study that, before planning/implementing orthodontic treatment on a patient with congenital missing incisors, some factors like retroclination of alveolar bone and reduced mandibular alveolar bone area should be taken into consideration, as these may affect the treatment outcome (28).

Some orthodontists say that congenital absence of both mandibular central incisor is advantageous, as the extraction of mandibular central incisors is sometimes considered as the treatment of choice in crowded class I malocclusion, especially when a preexisting tooth-size discrepancy (severe mandibular excess) prevents the achievement of an acceptable occlusion (29, 30).

The other consequence of agenesis of both mandibular incisors is disturbance in tongue-lip pressure balance and lack of lingual support. Severe malocclusion usually class II Div I malocclusion is also seen with severe anterior deep bite and absence of dental midline or sometimes wide spacing in the anterior region exists resulting in unaesthetic appearance for a child.

The other problem encountered with congenital absence of incisors is the difficulty in identification of teeth. Because of the existing space resulting from missing teeth, the adjacent teeth move to this space, leading to difficulty in identification of incisors. Thus, for correct diagnosis of teeth, radiographic examination is mandatory in order to see the exact position of the root.

Conclusion

The association of the two anomalies is rarely met in specialty practice. The impacted canines are part of the group of position dental anomalies, while agenesis is part of the number dental anomalies. The treatment is differentiated, on the two arches, the therapeutic objective being different in the two arches, thus:

-In the inferior arch we will choose the closing of the distance by physiological mesializations.

-In the upper arch we will choose the surgical exposing of 1.3 and bringing it on the arch by the slow tractioning, to a fixed poly-aggregate orthodontic appliance.

Due to the age of patient (only 14 years of age), we decided that orthodontic treatment is the proper choice in this particular case.

Ethical considerations

Ethical issues (Including plagiarism, informed consent, misconduct, data fabrication and/or falsification, double publication and/or submission, redundancy, etc.) have been completely observed by the authors.