TOWARDS A D3G GUIDE FOR DIAGNOSING MOLAR HYPOMIN

As noted here, D3G aims to develop guidelines that are both clinically useful and research friendly. Collaborative input is sought from the practitioner community, so please let us know what you think as the nascent ideas take shape.

The Basics

As a general rule, Molar Hypomin is quite straightforward to diagnose once you know the ropes. We think it's important to not only recognise the key features of a "pristine case", but also to understand how and why these characteristics may change over time. And to be proactively vigilant for this common problem, it helps to know the "red flags" that might crop up on initial presentation.

Clinical Alerts

Unusual caries  (see more)There are three common features that may alert you to Molar Hypomin:

  • obvious Hypomin lesions – perhaps of aesthetic concern to the patient
  • unusual caries – restricted to one or more molars, often contradicting good oral hygiene status
  • dental pain – localised to the affected molars often

In any particular patient, the clinical appearance will depend to a large extent on how long the affected teeth have been erupted.

Spotting it Early

Generally a Hypomin Molar is easiest to spot soon after it emerges into the mouth – that is, before complicating factors set in. So for a typical case of Molar Hypomin presenting in a 6- to 8-year-old child, we like to diagnose at individual-tooth and whole-mouth levels as follows:

Typically, a newly-erupted Hypomin Molar will exhibit:

  • patches of opaque enamel (i.e. lesions) with abnormal colour (white, cream, yellow or brown)
  • normal thickness of enamel throughout the lesion
  • intact enamel surface throughout the lesion, but this may not last for long
  • lesions of varied size and shape, located in the cuspal half of the crown
  • and sometimes a painful response to regular stimuli (tooth brushing, cold, heat, airstream)

A typical Molar Hypomin mouth may have:

  • from one to four Hypomin 6-year molars (6s, obligatory), plus/minus...
  • one or more Hypomin Incisors (generally less-affected than the molars), plus/minus...
  • Hypomin in the Es (primary second molars) too

Spotting it Late

With time, a Hypomin Molar may change its initial appearance quite radically, reflecting inherent weaknesses of the abnormal enamel (i.e. soft, porous & caries prone). And at whole-mouth level, other clues and complications may manifest as follows:

Typically, severely-affected Hypomin Molars will progress through these four steps:

  • surface pitting of the opaque enamel lesion, perhaps associated with extrinsic staining
  • further degradation and breakdown of the lesion, leaving sharp/fractured margins usually
  • caries involvement (cavitation), with progressive loss of the Hypomin borders
  • eventually, severe caries may be all that remains apparent

At later stages, a Molar Hypomin mouth may have:

  • some molars with severe caries, and other teeth with Hypomin still visible
  • unusual restorations in molars or incisors – location & shape consistent with Hypomin

Atypical cases of Molar Hypomin and Enamel Hypomin

As noted above, a typical case of Molar Hypomin involves the 6-year molars (6s), with or without co-involvement of the incisors (1s, 2s) and/or Es. However it's important to realise that other presentations can occur as any other tooth in the adult and primary dentitions can be affected by Enamel Hypomin. When any molars (6s/7s/Es/Ds) are co-involved with teeth other than adult incisors, the case may be called atypical Molar Hypomin – and if not, then the case can simply be described as "Enamel Hypomin affecting teeth X/Y/Z".

The most common atypical cases include involvement of:

  • primary molars and canines (Es > Ds > Cs) – consistent with earlier causation
  • adult canine (3s) – particularly the cusp tips, consistent with later causation
  • adult second molars (7s) or premolars (4/5s) – consistent with even later causation still

Checking it's not something else

To ensure your case is Molar Hypomin and not something else, a differential check can be run against the prime alternatives as follows:

1. Is it Amelogenesis Imperfecta?

 

Amelogenesis imperfecta

Molar Hypomin

Affected teeth

All

First molars, sometimes incisors

Family history

Yes, almost always

Not usually, but possible

  • see an example of AI hereAI Thumbnail Pic

2. Is it Dental Fluorosis?

 

Dental Fluorosis

Molar Hypomin

Affected teeth

Many, mostly incisors

First molars, sometimes incisors

Chronological pattern

Symmetrical usually

Often asymmetrical

Lesion borders & opacity

Diffuse borders, mottled

Demarcated borders, dense

Lesion colour

White usually

White or cream/yellow/brown

  • see an example of dental fluorosis hereFluorosis Thumbnail Pic

3. Is it a Chronological Defect?

 

Chronological Defect

Molar Hypomin

Affected teeth

Many, mostly incisors

First molars, sometimes incisors

Chronological pattern

Symmetrical

Often asymmetrical

Lesion feature

Linear, right across tooth

Non-linear, localised areas

  •   see an example of chronological defect hereChronological Defect Thumbnail Pic

4. Is it Enamel Hypoplasia?

 

Enamel Hypoplasia

Molar Hypomin (w. breakdown)

Affected teeth

Any, no bias towards first molars

First molars, sometimes incisors

Lesion border

Rounded edge & regular outline

Sharp edge & irregular outline

Missing enamel

Before, during & after eruption

After eruption only

  • see an example of enamel hypoplasia here  

5. Is it normal Dental Caries?

 

Dental Caries (normal enamel)

Molar Hypomin (with caries)

Affected teeth

Not restricted to first molars

Restricted to first molars often

Usual locations

Occlusal, interproximal, cervical

Cuspal, occlusal & not cervical

Plaque-associated

Yes, often obviously

Low-plaque areas often

Hypomin enamel visible

No

Often yes (same or another tooth)

  • see an example of dental caries here (help: great images needed)