DENTAL SPEAK: The ceramic crown is finally set right and fitted

A premolar or a molar which has had a traumatic onslaught on it either resulting from a physical fall by the patient, road accident or even a small stone in rice while partaking his food may undergo a fracture. The tooth breaks in various ways. The physical force can chip off a small section from the body of the tooth or it could involve a large section. The small section that has separated from the mass of the tooth may just involve the enamel. A large segment of tooth thus broken off may have both enamel and dentin. Enamel is the outer most covering of a tooth.

Enamel consists chiefly of hydroxyapatite crystals which are its inorganic component. They make up more than 98 per cent of its constitution. The rest of its composition consists of organic material made of glycoprotein and keratin-like protein. The microscopic section of enamel shows rods.

Dentin is the intermediate portion that lies between enamel and the pulp, the vital portion of the tooth that harbours tiny nerve fibrils and capillaries. It is the ‘ivory’ forming the mass of the tooth. About 20 per cent dentin makes up the organic matrix, mostly collagen. The inorganic fraction of dentin 80 per cent – is mainly hydroxyapotite.

It is the inorganic portion of the tooth that provides it hardness, while the organic portion lends it softness. The femur and temporal bone of the skull are the strongest bones of the human body. The tooth enamel, however, is the hardest and most highly mineralized substance in the human body. The enamel is categorized as a tissue and not bone.

Incidentally the hydroxyapatite is a naturally occurring mineral form of calcium apatite. It is a phosphate mineral. A fractured tooth with involvement of enamel alone can be conserved with a composite or silver amalgam filling. A fracture that brings about an exposure of the pulp needs root canal treatment after which a ceramic crown is made once the tooth has been prepared to receive it.

Out of 15 patients since the beginning 2016 who had crown works in their mouths, eight had exposure of their pulps first necessitating root-canal treatment. Three had ceramic crowns made because their esthetics was compromised as the crown/s had to be placed on upper anterior teeth. Two had flattened molars, which were rescued by placing crowns on them.

This feature deals with the narrative of a 64-year-old male patient who had a ceramic crown placed on his upper left first molar. The crown was cemented on January 15, this year. The patient returned on the 19th with the complaint that the ceramic had chipped off from the distal end of the crown as he was chewing hard meat.

A crown remover was used to dislodge the damaged ceramic crown. A new crown was made and fitted. This was fixed on February 10. The patient returned on February 16 stating that the crown was trapping a lot of food filaments both mesially and distally. Upon examination and probing a lot of food debris was disentangled. The crown had to be removed. New impressions taken, fresh casts were made and the ceramic crown was prepared for the third time.  The dental surgeon in order to ascertain what was the reason for so much of laxity if not lack of gravity in preparing the ceramic crown, the ceramist said that there had been power cuts in the area he had his dental laboratory. He had finally managed to have a generator (12.5 KW) installed and there would be no interruption in adjusting the exact temperature of the furnace in which ceramic was being baked.

The DS was hugely embarrassed since the confidence of the patient in his credibility was shaken. The newly made crown was finally placed on the molar. The DS said, “I am certain this time that you will have no further grievance. I am sorry that you had to undergo a lot of bother. This is the first time that a crown had to be repeated and that too thrice.”

The patient came back on March 26. The DS upon seeing him was almost left stuttering, “Oh, no! Not again!” The patient allayed his anxiety, “Doctor, my crown is good. I am enjoying eating on both sides now and the reason for being here is that I want to fix an appointment for my boss who broke his upper central tooth while trying to open a bottle of coke with his teeth”. The DS breathed a sigh of relief.

Dr K. S. Gupta is a dental surgeon with a private clinical dental practice