Some dentists use devices called "pins" to anchor very large fillings placed in your teeth. The pin or pins are countersunk with a handpiece (dental drill) half way into your tooth outside its nerve chamber (canal) after all decay has been removed. The other half projects into the overlying filling material to secure it in place. Pins should not be confused with posts or implants. Posts are larger devices that are manually inserted into the canal of your tooth after its diseased nerve has been removed by means of endodontic therapy (a "root canal"). In many such cases, much of your tooth above the gum line has been lost and the post retains the core material used to restore this lost tooth structure prior to coverage with a crown (cap). Implants are an altogether different matter as they may remind you of a pin or post in shape, but they actually replace the roots of missing teeth in their entirety. While pin placement is a fairly common practice in dentistry, Dr. McArdle does not perform this procedure in his office and has not for some time.
2 pins were placed in this tooth prior to filling it.
A slight crack can already be seen between them.
The reason for this is that has been Dr. McArdle's experience that pin placement carries a high risk of complications that he believes can be avoided by using other types of restorations beyond fillings or other methods of retaining extensive fillings besides pin use. The complications that pin introduction can produce include extreme temperature sensitivity, discomfort on chewing, tooth fracture (much like a hammered nail can split a board), nerve violation with subsequent nerve death leading to odontogenic (tooth borne) abscess, long-term nerve irritation prior to death with resulting tooth abscess and tooth loss if any of these conditions are too severe.
To completely avoid the need for pins in the first place, Dr. McArdle encourages the use of crowns (caps) instead of massive fillings. Very large fillings, even without pin retention, can present with many of the difficulties noted above. While the fractures that typically occur with large, non pin-retained fillings are less likely to end in tooth loss, the incidence of fracture is nonetheless high in these instances. Since the probability that fracture that will end in crown placement anyway in these cases is high, it is better to avoid the wasted expense and needless discomfort of the troubles associated with huge fillings in the first place.
If crowning your tooth is inappropriate for any reason, Dr. McArdle has other means of stabilizing large fillings in your teeth that preclude the need for pins. Dr. McArdle advocates the "amalgapin" technique wherein small channels are cut into your tooth while it is being prepared for a silver amalgam filling that are later occupied by the filling material as it is condensed into your tooth. This approach eliminates the tension created in your tooth by the countersunk pin and prevents many of the failures previously noted with pin use. Where suitable, the so-called "bonded" fillings made of tooth colored composite resin can be utilized that adhere to your teeth chemically. Silver fillings can also be bonded to your teeth, but the average bond strengths between silver amalgam and tooth structure are not as great as those between tooth structure and composite resin. Glass polymer restorations for your posterior teeth that are shaped much like fillings, but are made in a dental laboratory like crowns, are alternatives to crowns or fillings. They can be bonded in place with the same efficacy as composite resin while having a wider variety of uses like amalgam and bolstering your remaining tooth structure like a crown. These restorations are less practical for molar teeth and not indicated when your tooth has lost one of its cusps (corner posts). If you have any questions about the pros and cons of pin retention, please ask Dr. McArdle.