Socket Preservation for Implant Placement: Fact or Fiction
 

Consider the following statements.

1. During an extraction bone preservation is achieved by using gentler forces and newly designed instruments.

2. Grafting an extraction site is the preferred treatment when an implant is going to be placed because it gives better quality of bone sooner.

3. Once you have grafted an extraction site the bone dimensions are maintained indefinitely as long as an implant is placed to stimulate the bone.

The idea that teeth just need to be taken out more gently in order to preserve bone is a fallacy.  We have all taken out teeth that have no crown and no bone loss to know light gentle forces will not be effective.  The force must be directed at a specific area after the socket has been prepared to remove a tooth like this.  The instrumentation we use has not changed with the exception of the periotome.  In most situations, the periotome is ineffective because the dull flat spatula-like end and narrow neck will deform under pressure.  What has really changed in removing teeth, with reference to socket preservation, is the technique.  All textbooks show the classic envelope flap with releasing incisions and buccal ostectomy to remove roots.  Today, almost all exodontia is done flaplessly and without buccal or lingual bone removal when an implant is anticipated.  If we can preserve the four bony walls, the width and height can be maintained, the healing time will be less, and there will be no need for a costly graft and membrane.

The second statement is a fallacy because grafted sites have a longer healing time.  The reason grafted sites heal more slowly is because the graft material (essentially dead bone) is used as a scaffolding for new bone to grow in between the bony fragments.  In order for this site to mature and form solid bone, a large portion of the bone graft material has to be resorbed and replaced with new bone.  This resorption and apposition of bone slows healing thus delaying implant placement.  A grafted site has a healing time of approximately six months versus three months for non-grafted sites.  At three months a non-grafted site looks like bone but in a grafted site, even at 6 months, the bone graft material is easily visible and often softer than a non-grafted site that’s had half the healing time.

The criteria we use to graft sockets is when the  labial or lingual plate is missing and the bone graft is used to maintain alveolar width.  The one caveat: in the esthetic zone we will sometime place a graft even when the buccal plate is intact but thin, or if losing any bone height is a concern.  Also, we have had poor results when using particulate grafts to increase bone height.  In order to increase bone height, we use a titanium mesh with Allografts, PRP, and BMP or use Distraction Osteogenesis.    

The third statement is false because all extractions, whether grafted or not, with or without an implant, will remodel and lose width until the bone has reached equilibirium with the load placed on it.  How much remodeling is dependent upon: the thickness of the cortical bone, the extraction technique, bone quality and density, whether or not the site has an implant and time.  Numerous studies, notably Chen et al. in 2005 and 2007 and Covani et al. in 2003, show a 35% reduction in bone width in extraction sites with immediate implants without grafts over a six month period.  In extraction sites where implants were placed with grafts, they saw a 24% reduction in buccal-lingual bone dimensions.  Mind you, both of these are short term studies of six months.  These results shouldn’t be surprising because we know that bone will adapt to the load placed on it (Wolf’s Law).  Since an implant is narrower than the tooth it replaces and is usually placed more toward the palate, we would expect the buccal bone to remodel, and continue to remodel, even after six months.  Once the bone reaches equilibrium with the forces placed on it, the width will be maintained.
 
Although these concepts are controversial, they are based on the best scientific studies available and over 25 years of experience.  Feel free to contact our office if you would like more information on flapless extractions to avoid grafts and membrane.

Michael R. Stohle, D.D.S., M.S.

References:
Chen St. et al.  Clin. Oral Implants, Res 2005; 16: 176-184
Chen St. et al.  Clin. Oral Implants, Res 2007; 18: 552-562
Covani U. et al.  I Peridontology 2003; 74: 268-273