A clinical case by our Community member Dr. Nisha Deshpande
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Molar-incisor hypomineralisation (MIH) was first defined in 2001 by Weerheijm et al. and as “hypomineralisation of systemic origin, presenting as demarcated, qualitative defects of enamel of one to four first permanent molars (…) frequently associated with affected incisors”. In 2003, MIH was described as a developmental, qualitative enamel defect caused by reduced mineralization and inorganic enamel components which leads to enamel discoloration and fractures of the affected teeth. Although the etiology remains unclear, the localized and asymmetrical lesions seem to have a systemic origin. The clinical presentation of MIH depends on its severity and can range from whitecreamy opacities, yellow-brown opacities, post-eruptive enamel breakdown, to atypical caries located on at least one first permanent molar with or without incisor involvement.
Common clinical problems for patients with MIH are:
• Post-eruptive enamel breakdown leading to dentine exposure which increases the risk of pulp involvement
• Tooth Sensitivity
• Aesthetic Problems
• Difficulty in administering local anaesthesia
• Tooth loss
Although resin infiltration has shown good results in mild MIH cases with superficial white lesions, deeper lesions require a modified technique for the aesthetic management of incisors, called “deep resin infiltration technique” (Attal et al.). This technique involves preparation of the affected tooth by macroabrasion, either by intraoral sandblasting or a round bur at low RPM to ensure that the infiltration can indeed reach the full extent of the lesion in case of MIH.
A young girl, aged 12 came into our dental office with the chief complaint of the dark brown area on her front tooth. She expressed her embarrassment at school and social situations where she was being teased about the brown spot causing her a lot of despair.
History and examination revealed the presence of brown discoloration of 11, 13, 23 and 41. Both lower first permanent molars were root canal treated at the age of 9 and given metal crowns. The upper permanent molars showed large composite restorations with hypomineralized tooth surfaces. According to the classification of MIH by Mathu – Muju and Wright, this case could be classified as Severe MIH, i.e. post-eruptive enamel breakdown, crown destruction, caries associated with affected enamel, history of dental sensitivity and aesthetic concerns.
Pre operative upper anterior close up reveals a well demarcated brown lesion with 11. The lesions on the other teeth were not a primary concern for the patient hence it was decided to only treat the lesion on 11 and also 23 which showed a discontinuity of the mesial surface, making it prone to caries. The lesions on 13 and 41 had a hard enamel surface and would be checked at regular follow op visits for further treatment. Tooth 11 would be treated with macroabrasion, Deep Resin Infiltration (with ICON, DMG) and composite restoration, while tooth 23 would be treated with a proximal composite restoration.
Isolation with rubber dam is mandatory to ensure excellent protection of the soft tissues and too create contaminant-free environment for infiltration of the lesion and for bonding of the composite.
Macroabrasion is done with a large round bur at slow speed to remove the superficial enamel. This allows deeper penetration of the acid and subsequently the infiltrant to effectively mask the discoloration. The enamel is removed with a very smooth, shallow and controlled movement of the bur without causing any deep pits.
A coarse disc (Shofu Snap on Disc) is used to smoothen the margins of the preparation to allow better blending of the composite material.
After thoroughly washing the etching gel and drying the surface, the next step in the infiltration technique is the Icon Dry (alcohol solution). It is applied for 2 minutes in order to visualize the result achievable with resin infiltration. If the desired result is not achieved, these 2 steps can be repeated up to maximum 3 times, according to manufacturer’s instructions.
We decided to stop after 2 cycles of Etch and Dry.
After using a mylar strip to separate the teeth, the Icon Infiltrant is applied on the tooth surface for 3 minutess and then photocured for 40 seconds. This is repeated for 1 minute more and photocured.
This was the situation after resin infiltration. Some yellow area is still visible but it will be covered with a layer of composite resin.
Photocuring under a layer of glycerin gel.
Immediate post operative result. We must always wait for rehydration of the teeth for at least 48 hours to assess the final result.
Final situation after 2 weeks showing acceptable integration and aesthetics.
When used following the correct techniques and protocols, ICON can be used to treat discolorations in the aesthetic zone of patients with MIH to provide them with a minimally invasive solution and acceptable aesthetics, restoring their lost confidence.
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