Tooth agenesis: causes and treatment

What tooth agenesis is

Tooth agenesis is the congenital absence of one or more permanent teeth, due to the failed development of the tooth germ. We speak of hypodontia when one to five teeth are missing (excluding third molars), oligodontia when six or more are missing, and anodontia, rare, in case of total absence. It is a common condition: in European populations the prevalence of congenitally absent permanent teeth is estimated between 3% and 11%, and in an Italian orthodontic sample it was around 9%. In most cases only one or two teeth are missing.

Which teeth are most often missing

Agenesis does not affect teeth at random. The most frequently absent are the mandibular second premolars, the maxillary lateral incisors and the maxillary second premolars. The site of agenesis guides the strategy: the absence of a lateral incisor, in the aesthetic zone, raises different problems from that of a premolar in a posterior sector.

Why agenesis is not only an aesthetic matter

When a tooth does not develop, the alveolar bone that would have supported it does not form adequately: the bony ridge at the agenesis site is often thin or reduced in height. To this are added possible consequences for occlusion, for the position of neighbouring teeth and, at times, for the persistence of the corresponding deciduous tooth. It is a decisive clinical point: it determines whether and how an implant can be placed, and it is the reason the assessment is not limited to the missing tooth but considers the entire biological context of the site.

Treatment options

There is no single solution. The choice arises from a clinical, radiological and occlusal assessment, and from an honest discussion of the prognosis.

Orthodontic space closure. Orthodontics brings the adjacent teeth together, closing the space of the missing tooth. Where feasible, particularly for the lateral incisor, it is often preferable on the periodontal and economic level, because it avoids a prosthesis. Systematic reviews show no clear aesthetic difference compared with the implant, and in some analyses space closure is rated better.

Space opening and prosthetic replacement. When closure is not indicated, the space is maintained or recreated and the tooth is replaced with an implant or, in selected cases, a minimally invasive resin-bonded bridge. Conventional tooth-supported prostheses tend to report worse periodontal outcomes than space closure.

Tooth autotransplantation. In particular situations, and in young patients with suitable donor teeth, the transplantation of one’s own tooth may be considered.

Timing matters: in growing patients the implant is postponed until skeletal growth is complete, because an implant does not follow bone growth.

When an implant is needed: the problem of insufficient bone

This is the technical difficulty of agenesis. The site often lacks enough bone to receive an implant, and the conventional route involves a bone graft (autologous harvest, or materials of animal or synthetic origin) before or during implant placement. Graft outcomes are documented and reliable, but they involve a second surgical site or the use of biomaterials, longer times and a more complex biology.

An alternative approach exists, in selected cases: the MTM approach (Morphogenic Tissue Management), developed in Rome by Dr. Gaetano Calesini, which aims at bone and muco-periosteal regeneration in cases of predominantly horizontal bone atrophy, without grafts, membranes or heterologous materials, using the biological signals present at the site during implant placement. It is an elective procedure, indicated only after a clinical, radiological and instrumental assessment. Where applicable, it changes the balance between invasiveness, time and biological management.

The Studio Calesini approach

At Studio Calesini the decision does not start from the missing tooth, but from the person and the site: clinical and radiographic data are gathered, occlusion and development are assessed, and the options are compared with a prognosis stated transparently. The dual medical and dental-technician competence of Dr. Calesini allows the case to be followed from diagnosis to prosthetic completion. When an implant is the correct choice and conditions allow, the MTM approach is one of the possibilities for addressing the bone deficit without a graft.

Frequently asked questions

Is agenesis hereditary? Often yes: it has a genetic component and can run in families, sometimes associated with other developmental conditions.

Can an implant always be placed? No. It depends on the available bone, on age (growth must be complete) and on the occlusal context. In some cases orthodontic space closure is preferable.

Should a deciduous tooth that was never replaced be removed? Not necessarily straight away: if stable it can be kept for a period, but its long-term prognosis must be assessed case by case.

How long does one wait before an implant in a teenager? Until skeletal growth is complete, because an implant does not accompany bone development.

Tooth agenesis: what it is and how it is treated