In the daily practice we are often challenged by cases of severe dental decay . The dentist is always challenged by the decision to extract and replace with an implant or the decision to save the tooth but with a doubt on the long term prognosis . We know from several articles, like for example the article of Seltzer and Kim ( Comparison of Long term survival of implants and endodontically treated teeth J Dent Res 93(1):19-26, 2014), that recovering teeth is a better option , especially in younger patients . The missing key of the puzzle for the general dentist is often a good biomechanics evaluation of the residual dental structure . Most of the failures of endodontically treated teeth is , in fact , related to mechanical failures like crack and fractures . A careful biomechanical evaluation of the residual dental structure together with focusing on techniques able to improve the mechanical performances are chief in the search of long term outcome . In the practice of the author the combination of use of vertical preparation with a minimal approach together with the use of orthodontic extrusion are game changer in restorative dentistry , like is showed in the following case .
A caucasian male , 35 years old , patient came to our office for the fracture of the tooth 1.4 (upper first premolar ) , the fracture was oblique . In the restoration of compromised teeth one of the most important step is the biomechanics evaluation of the remaining structure . A mistake in this phase is detrimental on the long term outcome . Most of the cracks , for example , are generated by the wrong preparation of dental cavities for restorative dentistry . In the same way a wrong evaluation of the remaining structure may lead over time to a failure related to mechanical reasons.
Occlusal view showing the amount of tooth structure , in the xray is also possible to appreciate a Class II decay on tooth 1.5 . Even if possible to treat these cases with a crown lenghtening approach , the final result is , on average , not satisfactory . The recovery of the ferrule is limited and we have also periodontal complications like black triangles , root exposition of neighboring teeth . Orthodontic extrusion is way more advantageous .
Tooth 1,4 and 1,5 have been isolated under rubber dam . Tooth 1.5 has been restored with a direct technique with a selective caries removal approach in order to avoid an endodontic treatment .
Tooth 1.4 has been endodontically treated .
In order to recover tooth structure and improve the resistance of the tooth-restorative complex a orthodontic extrusion has been performed using a wire bonded on the neighboring teeth and a simple elastic ligature .
Follow up of the extrusion after couple of weeks . At the end of the extrusion a small recontouring of the soft tissues has been executed. The author usually performs the extrusion without fibrectomy and at the end of the extrusion does a recountouring of soft tissues.
The tooth after the extrusion and the vertical preparation . Vertical preparation are the best preparations regarding the ability to maintain tooth ’s structure especially when used with a minimally invasive approach . The author is using a modified vertical technique with higher focus on the maintenance of the pericervical dentin .
Recovered buccal wall
Comparison between Buccal structure before /after extrusion . The occlusal load on the residual dental structure is now much more favorable for a long term outcome .
(35% wall height)
Even on the palatal wall we had a gain of dental structure . Around 35% of the palatal wall is now on sound dental structure . This allows a much better outcome for the future restoration due to improved biomechanics.
Cementation of the Zirconia Crown with a GlassIonomer Cement . Using this approach is evident the amount of ferrule gained without any kind of complications to neighboring teeth . The periodontal apparatus is , in fact , untouched . No black triangles , no risk of root exposition of neighbouring teeth . Already the day of the delivery we have the papillae filling the inteproximal spaces . The amount of ferrule gained is massive . On the buccal wall we can easily recognize that the whole wall is now on sound dental structure and ,on the palatal wall, we have much more than the recommended 1-1,5 mm .
With vertical preparation we can also keep easily the amount of recovered dental structure , especially the area of the pericervical dentin that is the most important for the long term outcome .
After the rise of implantology , the bar in restorative /prosthetic dentistry has been raised . To “compete “ with dental implants in a more successful way , dentists have to focus much more on evaluate and improve the biomechanical situation of teeth . A deep comprehension of biomechanics together with the implementation of technique able to improve tooth’s ability to bear loads is chief in the search of a long term success.