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To cover or not to cover the cusp, that is the question

A clinical case by our Community member Dr. Khalid Jamal Mohammed

This article and its content are published under the Author’s responsibility as an expression of the Author’s own ideas and practice. Styleitaliano denies any responsibility about the visual and written content of this work.

Dentistry is in a continuously evolving state, which leans towards the minimal invasive approaches. It is nowadays recognized that all tooth structure removed in the process of removing carious tissue is considered to be a loss that cannot be restored. Contemporary dentistry is all about maintaining as much tooth structure as possible, therefore, all the efforts are now focused on producing instruments that serve this purpose, which in turn open the door to new protocols and standards aimed at maintaining sound tissues. In our case study we put the spotlight on the magnificent benefits offered by the LM Cusp Misura, an instrument aimed at instantly informing the dental practitioner about the predictability and strength of the remaining structure that will have to withstand masticatory forces based on the minimum width (2 mm) and depth (4mm ). This in turn guides the dentist with regards to how much reduction is required without the need for indirect solutions.

molar with extended decay style italiano styleitaliano

Fig.1
A young female patient presented to the clinic with spontaneous pain at the lower left first molar; the patient also complained about food impaction. A large carious cavity was found upon examination.

isolated field before caries removal styleitaliano style italiano

Fig.2
After isolation with the rubber dam, we started cleaning the cavity. Pre-wedging was used to avoid harming the proximal periodontium.

pulp exposure during decay removal style italiano styleitaliano

Fig.3
Caries reached the pulp, as you can see from the bleeding in the distal area.

clean pulp chamber style italiano styleitaliano

Fig.4
Tooth was cleaned form carious lesion, pulp tissue removed and irrigation protocol intimated (Normal Saline and Sodium Hypochlorite) to stop the bleeding. We decided to go with a minimally invasive approach. Distobuccal and distolingual cusps were weak.

LM arte cusp misura instrument for measuring dental cusps style italiano styleitaliano

Fig.5
A unique instrument, such as the LM Arte Cusp Misura is ideal for evaluating the width of the remaining tooth structure, and choosing the restorative technique to be used. If the forked instrument tip penetrates up to its marks, the tooth structure is too weak to withstand occlusal forces with a direct restoration, and other clinical options must be considered.

LM cusp misura instrument on tooth style italiano styleitaliano

Fig.6
Using LM Cusp Misura to check cusp hight and width starting with the distobuccal one. As it was thinner than 2 mm, the risk of fracture was high, so we decided to proceed to cusp coverage after endodontic treatment.

LM cusp misura measuring buccal cusp style italiano styleitaliano

Fig.7
Another view shows Misura in action.

LM cusp misura measuring lingual cusps style italiano styleitaliano

Fig.8
The same instrument was used to measure distolingual cusp, which was also too thin, so coverage was needed for this cusp as well.

LM cusp misura measuring lingual cusps style italiano styleitaliano

Fig.9
Another view shows Misura in action.

tooth after cavity preparation and cusp reductio styleitaliano style italiano

Fig.10
Distal cusps were reduced, all unsupported enamel was removed.

endodontically treated lower molar style italiano styleitaliano

Fig.11
Endodontic treatment was performed, and the gutta percha was cut at the canal orifice. The tooth was ready for overlay preparation.

flowable filled endodontic cavity style italiano styleitaliano

Fig.12
Covering the pulpal floor with flowable composite.

acid etching of cavity before overlay cementation style italiano styleitaliano

Fig.13
After impression of the prepared tooth, we were ready to cement the overlay Emax restoration. Acid etching was carried out for 20 seconds on the preparation and on the overlay restoration (with hydrofluoric acid and phosphoric acid for the different substrates).
A universal adhesive, and dual-cure resin cement were used for cementation.

cemented overlay restoration style italiano styleitaliano

Fig.14
Immediate result after cementation, occlusal adjustment.

Conclusions

Maintaining sound tooth structure should be the prime goal of every restorative procedure, despite the fact that the tooth has lost its vitality which makes it more prone to fracture than vital teeth. To serve this purpose a precise measurement of the remaining tooth structure should be done. A unique instrument known as Cusp Misura (LM) was used to determine the remaining tooth structure in the cusp area, thus leading to cusp coverage of the distal occlusal surface.

Bibliography

1. Veneziani M. Posterior indirect adhesive restorations: updated indications and the Morphology Driven Preparation Technique, Int J Esthet Dent 2017, 12(2):204-230
2. Musella V. Modern Aesthetic Dentistry: An A to Z Guided Workflow. Quintessence Pub 2017
3. Magne P. Composite Resins and Bonded Porcelain: The Postamalgam Era? J Calif Dent Assoc 2006 34(2):135-147
4. Duarte S et al Adhesive Resin Cements for Bonding Esthetic Restorations: a Review, QDT 2011, 34:40-60

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