Baby teeth start forming when the foetus is still in the womb. The first baby tooth appears at around 8 months of age. By the time the child is 3-years-old, all 20 teeth can be seen in the oral cavity.

These milk teeth are replaced by the permanent teeth. The first milk teeth begin to shed and are replaced by the permanent teeth at around 6 years of age. Till the age of 14, every permanent tooth except the third molars can be detected in the oral cavity.

The primary or milk teeth's shedding in order to make way for the permanent successors is a normal physiological process. When the permanent teeth exert their eruptive forces underneath, the roots of the primary tooth begin to resorb. The resorptive process makes the tooth loose and mobile, following which, they exfoliate.

Baby teeth don't want to fall out !?

But there are instances when a primary tooth does not fall off. There are many reasons for this. The most common reason is the total absence of the permanent tooth bud underneath. In case a permanent tooth bud is present, but has not replaced its predecessor, then it can be because of a change in the eruption path of the permanent tooth. This can be because of a cyst, tumour or any other pathology that may be present under the primary tooth.

Patients who suffer from systemic conditions that are familial, affecting the osseous architecture of the tooth and its surrounding ligament and the bony framework of the body in general are prone to the retention of milk teeth. Ankylosis of the tooth means the pathological fusion of the tooth with the bone. If a primary tooth is ankylosed, then it might not get resorbed or fall off. Moreover, it can also lead to infraocclusion, i.e., the tooth unable to intercuspate or meet in the bite with the tooth of the opposing arch. Chronic malnutrition and compromised immunity are some of the factors that contribute towards the retention of primary tooth.

The consequences of an over retained or persistent deciduous tooth has a lot of clinical relevance. The underlying permanent tooth might erupt in a different direction if there is an over retained tooth. The ectopic eruption of the permanent tooth leads to malocclusion of teeth which in turn affects the orofacial musculature.

A commonly observed condition in cases of persistent deciduous teeth is crowding of teeth. The prolonged retention means that there is less space for the accessional teeth to erupt and in order to find their place in the oral cavity. They will then erupt in malaligned positions, causing orthodontic problems like crowding.

How can we diagnose retained baby teeth (deciduous teeth that haven't fallen out)?

Diagnosis of an over retained tooth can be made both clinically and radiographically. A radiograph confirms the retention of the deciduous teeth. The radiograph of choice is called an orthopantomogram (OPG). Treatment of an over retained tooth depends on multiple factors.

• If an over retained tooth has blocked the eruption of a permanent tooth, then it needs to be extracted in order to facilitate spontaneous eruption of the successor.
• If an over retained tooth is the reason behind crowded teeth, then it needs to be extracted in order to make space for the other teeth to align.
• If a primary tooth persists and the underlying successor's tooth bud is absent, then the over retained tooth should be saved in order to maintain the functional efficacy. In these cases, any carious involvement or aesthetic concerns of the retained tooth must be addressed and rectified.
• Over retained teeth in the anterior or front region might need recontouring for aesthetic reasons in case they are to be saved.
• In case an over retained tooth needs to be removed and there is no underlying successor, then the space created can be corrected by prosthetic treatments like partial dentures, bridges and implants.

Persistence of a milk tooth may or may not be detrimental. In order to avoid any negative consequences, a routine dental check-up is mandatory. It is in these sessions that the dentist may give the patient a hint or an indication of over retained teeth. A thorough medical history of the patient can help in better understanding the various factors associated with the normal eruption pattern of teeth. Treatment options can then be weighed out as mentioned above.