Management of congenitally missing second premolars with orthodontics and single-tooth implants

The Prevalence of Congenitally Missing Permanent Teeth in a Sample of Orthodontic and Non-Orthodontic Caucasian Patients

BACKGROUND

Hypodontia represents a notable clinical and public health concern.

OBJECTIVE

To assess the prevalence of congenitally missing permanent teeth in a sample of orthodontic/dental patients of Caucasian origin originating from the Greek island of Lesvos.

MATERIALS AND METHODS

Panoramic X-rays from 621 children and adolescents, aged 9 to 16 years (average age 12.5 years), 521 seeking orthodontic care (orthodontic group) and 100 seeking dental care (non-orthodontic group) were examined to identify congenitally missing permanent teeth.

RESULTS

The orthodontic group exhibited a 5.5% prevalence of congenitally missing permanent teeth (2.8% females; 2.7% males), while the non-orthodontic group showed a prevalence of 4% (3% females; 1% males). The descending order of prevalence for missing tooth types was as follows: lower second premolars, upper laterals, lower central incisors, lower canines, upper second premolars, and lower second molars. Among orthodontic patients with missing teeth, 62% presented with an Angle's Class II malocclusion. Hypodontia was most frequently observed in the mandible. No statistically significant differences were observed between the orthodontic and non-orthodontic groups in terms of the percentage of children and types of congenitally missing teeth.

CONCLUSIONS

Congenitally missing teeth were observed in about 4-5% of the studied population with a female predilection. The lower second premolar was the most commonly absent tooth, followed by the maxillary lateral incisors. An Angle's Class II malocclusion was present in the majority of orthodontic patients with hypodontia, mostly in the mandible.

The congenitally missing second premolar: Space closure. A viable option

Many treatment options are available to address the problem of missing second premolars. Extraction of retained deciduous second molars and subsequent space closure are often appropriate because this option alleviates the need for implants or other restorations. This article describes the conventional orthodontic closure of unilateral and bilateral congenitally missing second premolar spaces after the extraction of retained deciduous second molars.

Alveolar bone resorption after primary tooth loss has a negative impact on straightforward implant installation in patients with agenesis of the lower second premolar

OBJECTIVES

To compare the alveolar bone dimensions in patients with lower second premolar (P2) agenesis prior to and after primary molar loss on CT scans, and assess the possibility for straightforward implant placement.

METHODS

Alveolar bone dimensions were evaluated on 150 mandibular CT scans in three groups: (i) agenesis of P2, with the primary tooth in situ, and regularly erupted first premolar (P1) and molar (M1) (AW); (ii) agenesis of P2, without the primary tooth in situ for ≥3 m, but regularly erupted P1 and M1 (AWO); and (iii) P1, P2, and M1 regularly erupted (CTR). The possibility of straightforward placement of an implant 3.5 or 4.3 mm in Ø × 10 mm long was digitally simulated and compared to the actually performed treatment.

RESULTS

Buccolingual width (7.3 ± 2.0 mm) at the coronal aspect of the ridge in the AWO group was statistically significantly smaller comparing with both the AW (9.2 ± 1.4 mm) and the CTR (9.5 ± 1.1 mm) group; width reduction appeared to be mainly due to "collapse" of the buccal aspect of the ridge. Simulated straightforward placement of implants with a diameter of 3.5 or 4.3 mm was possible in 62% and 56% of the cases in the AWO vs. 86% and 84% in the AW group (p = .006 and .002, respectively). Straightforward implant placement was actually possible in all patients (22) in the AW group, while 28% (11 of 39) of the patients in the AWO group needed additional hard tissue augmentation.

CONCLUSIONS

Significant dimensional differences exist in the alveolar ridge, especially in the coronal part, at lower P2 agenesis sites missing the primary tooth for ≥3 m, when compared to P2 agenesis sites with the primary tooth in situ. It seems thus reasonable to advise that the primary second molar should be kept as long as possible, in order to facilitate straightforward implant installation and reduce the probability of additional bone augmentation procedures.

Second premolar agenesis is associated with mandibular form: a geometric morphometric analysis of mandibular cross-sections

The aim of this study was to compare mandibular form (i.e., size and shape) between patients with agenesis of the lower second premolar (P2) and a control group with no agenesis. Three hypotheses were tested: (H1) agenesis causes a change in mandibular morphology because of inadequate alveolar ridge development in the area of the missing tooth (mandibular plasticity); (H2) agenesis is caused by spatial limitations within the mandible (dental plasticity); and (H3) common genetic/epigenetic factors cause agenesis and affect mandibular form (pleiotropy). A geometric morphometric analysis was applied to cross-sectional images of computed tomography (CT) scans of three matched groups (n=50 each): (1) regularly erupted P2; (2) agenesis of P2 and the primary second molar in situ; and (3) agenesis of P2 and the primary second molar missing for >3 months. Cross-sections of the three areas of interest (first premolar, P2, first molar) were digitized with 23 landmarks and superimposed by a generalized Procrustes analysis. On average, the mandibular cross-sections were narrower and shorter in patients with P2 agenesis compared with that in the control group. Both agenesis groups featured a pronounced submandibular fossa. These differences extended at least one tooth beyond the agenesis-affected region. Taken together with the large interindividual variation that resulted in massively overlapping group distributions, these findings support genetic and/or epigenetic pleiotropy (H3) as the most likely origin of the observed covariation between mandibular form and odontogenesis. Clinically, reduced dimensions and greater variability of mandibular form, as well as a pronounced submandibular fossa, should be expected during the treatment planning of patients with P2 agenesis.

Induced ankylosis of a primary molar for skeletal anchorage in the mandible as alternative to mini-implants

BACKGROUND

Mesial protraction of mandibular posterior teeth requires increased anchorage to avoid undesired tooth movements. Orthodontic mini-implants have become a popular and successful way to increase skeletal anchorage in such cases. However, mini-implants may cause injury to adjacent teeth or anatomical structures and may lead to tissue inflammation. Induced ankylosed primary teeth have been used in the past as abutments for the protraction of the maxilla in cases of maxillary retrognathism. However, this technique has not been described in the literature for the protraction of mandibular molars. The aim of this paper is to present, through a case report, an alternative to mini-implant devices to maximize anchorage in the mandible by inducing ankylosis on a primary molar.

FINDINGS

A 13-year-old female with class II right malocclusion, deep bite, and congenitally missing right second premolars was referred for orthodontic treatment. Treatment plan involved removal of the primary teeth and mesial protraction of the posterior. In the mandible, ankylosis was induced on the retained primary second molar by extraction, bisection, replantation of the mesial part after endodontic treatment, and bonding of a rigid splint. Ankylosis was diagnosed after 10 weeks and a closing T-loop sectional wire was inserted to move the permanent first molar mesially. At 6 months, the remaining space was closed using elastic chain on a rectangular stainless steel wire with tip-back bends, supported by class II elastics.

CONCLUSIONS

Induced ankylosis of primary teeth can be an alternative to orthodontic mini-implants in selected cases, with minimal risks and maximum biocompatibility.

Orthodontic Considerations in Restorative Management of Hypodontia Patients With Endosseous Implants

The use of implant-supported restorations in patients with hypodontia remains challenging and requires a multistage treatment that begins in late mixed dentition and continues into late adolescence. The aim of this article is to review the role of orthodontics in endosseous implant rehabilitation of patients with hypodontia. The MEDLINE, Web of Science, Scopus, Cochrane databases, and necessary scientific textbooks were searched for relevant studies and reviews, and as far as possible, they were only included if they had been cited at least once in the literature. Dental implants are susceptible to overloading as the periodontal ligament is absent and the proprioceptive nerve endings are either lacking or very limited. Patients with hypodontia may present with skeletal features such as short and retrognathic maxilla, prognathic mandible, and shorter lower anterior facial height, and they sometimes need orthognathic correction as part of their overall treatment. Dental problems vary and include bimaxillary retroclination of incisors, spacing, centerline discrepancies, microdontia, hypoplastic enamels, ankylosis of the retained primary teeth, overeruptions, and volume deficiencies of alveolar ridges. The challenges mentioned, as well as bone volume deficiencies, compromise the successful placement of implants. Orthodontic strategies and techniques, such as uprighting mechanics, extrusion/intrusion, delayed space opening, and orthodontic implant site-switching, can be used to create, preserve, or augment the implant site. After orthodontic site development, the final planned position of the teeth should be maintained with a rigid bonded retainer; overlooking this stage may compromise the implant site and require orthodontic retreatment.

Evaluation of panoramic radiographs taken at the initial visit at a department of paediatric dentistry

OBJECTIVES

To examine oral and maxillofacial lesions other than those related to the chief complaint in panoramic radiographs taken at the department of paediatric dentistry at our hospital.

METHODS

We retrospectively reviewed all 1092 patients who had visited the department of paediatric dentistry at our hospital and had a panoramic radiograph taken between August 1999 and October 2004. The following information was obtained from the patients' files and panoramic radiographs: gender, age, chief complaints and the presence or absence of lesions.

RESULTS

Lesions were observed in 140 of the 1092 panoramic radiographs (12.8%). Among the 140 patients discovered to have lesions in the panoramic radiographs, 66 (47.1%, or 6.05% of the entire group of 1092 patients) had different lesions from those underlying the chief complaint. These 66 patients ages ranged from 3 years to 14 years and the lesions involved 39 (59.1%) missing teeth, 20 (30.3%) mesiodentes, 4 supernumerary teeth, 1 odontoma, 1 radicular cyst and 1 impacted tooth. The missing teeth were observed in the central and lateral incisor, canine, and first and second premolar positions of both jaws, especially in the lower lateral incisor and upper central incisor positions.

CONCLUSIONS

We were able to detect incidental lesions at a rate of 6.05% (66 of 1092 patients) and at a relatively early age (mean 6.8 years) in the present study. Early treatment of these lesions could avoid maxillofacial deformity and other complications.