SINUS AUGMENTATION

Maxillary atrophy, sinus augmentation

Sinus graft is a technique-sensitive procedure. The success of the procedure requires surgical and prosthodontic skills. 
Despite complications such as tearing of the sinus membrane, infection of the graft, or loss of the implants, it is rare that any long-term sinus complication occurs.
 
Tolman D. 1995. Reconstructive procedures with endosseous implants in grafted bone. JOMI 1995) 
The lining of the healthy sinus is a structure with immunologic homeostasis. Bathed with mucin, lactoferrin, sIgA, which inhibits epithelial colonization of microorganisms and in conjunction with ciliary action maintain a sterile sinus environment. The reparative capacity of the sinus lining is rapid and it returns to a sterile state soon after sinus graft wound healing. 
Misch CM. 1992. The pharmacologic management of maxillary sinus elevation surgery. J Oral Implantology. 1992
Endoscopy prior and posterior to the sinus grafting has demonstrated normal sinus function, including ciliary action. It appears that as long as the sinus graft does not extend high enough to interfere with ostium function, grafting in this area of the maxilla is not contraindicated physiologically and is generally benign procedure.
Watzek G. et al. 1998. Anatomic and physiologic fundamentals of sinus floor augmentation. Quintessence 1998.
 

Bone grafts and the sinus floor

A review of biopsy from of the sinus grafts been reported separately demonstrates that bone forms endosteally from the sinus floor with every material reported. As long as a pace is maintained beneath and an intact sinus lining to form a closed wound environment.
Lazzara RJ. 1996. The sinus elevation procedure in endosseous implant therapy. Current opinion in Periodontology 1996, 
Summers RB. 1994. A new concept in maxillary implant surgery. Comp Contin Educ Dent 1994
Jensen OT, Sennerby L. 1998. Titanium micro implants retrieved from human sinus cavity bone grafts. JOMI. 1998.


The addition of osseocoductive alloplast materials that maintain a apace above the sinus floor within a blood clot has been reported to be associated with bone formation that ascends from the floor of the sinus several millimeters up into the graft.
 
Jensen OT. 1998. Treatment planning for sinus graft.  The sinus bone graft, Quintessence 1998
Osteoinductive materials form new bone endosteally from the floor of the sinus as expected, but also form bone de novo within the graft depending on its osteoinductive (and osteoconductive) capacity.
Kirsch et al. 1998. Sinus graft using porous hydroxyapatite, in the sinus bone graft by Jensen., Quintessence 1998.
In general, autografts have been shown to be highly osteoinductive and therefore may be less dependent on sinus floor endosteal bone migration.
Marx RE. 1995. Osseointegration in natural bone, radiated bone, grafted bone. University of Miami Symposium Sylabus
 

Osteoinductivity

Materials containing BMP that have been used in the sinus include allograft, autograft , BMP-2,7, which by themselves include the complete consequence of bone formation.
 
Nevins et al. 1996. Bone formation in the goat maxillary sinus induced by absorbable collagen sponge implants impregnated with recombinant human bone BMP2. Int J Perio Rest Dent 1996. 
 

Allografts

Sinus allografts may have more late loading failure, more infections, and more stage 2 uncovering failures when compared to other materials.
 
Jensen OT. Greer R. 1992. Immediate placement of osseointegrating implants into the maxillary sinus augmented with mineralized cancellous allograft and Gore-Tex. Quintessence 1992.
Do they interfere with bone formation and osseointegration, implant fixation in the remodeling phase? vital/nonvital bone due to incomplete replacement by creeping substitution
Aspenberg et al. 1988. Rapid bone healing delay by bone matrix implantation, JOMI. 1988
The mechanical significance of this is unknown, but it probably makes fatigue failure more likely!
Frost H. 1998. Vital biomechanics of bone-grafted dental implants. In the Sinus Bone Graft by Jensen, Quintessence 1998.
 

Autografts

Animal studies using block autografts showed a high level of osseointegration compared to particulate autografts. Human studies?
 
Lew et al. 1994. A comparative study of osseointegration of titanium implants in cortico-cancellous block and cortico-cancellous chip grafts in canine ilium. J Oral Maxillofac Surg.1994. Intimacy of graft-vitality/fixation,consolidation/scar tissue vitality
 

Sinus graft healing

The way the various sinus grafting materials undergo angiogenesis, osteogenesis, consolidation, osseointegration, and remodeling requires more study to determine the exact mechanism of healing, establish the optimal grafting material, and further define the critical stages of healing.
Sinus lining/ endo-periosteum as the source of angioblast-osteoblast and /or Pluripotent cells and vascular capacity
Summers RB. 1995. The osteotome technique: part 4- future site development. Compendium 1995.
>No significance morphogenic protein or osseo-proliferative contribution is found from the infractured sinus wall, which demonstrates a more passive or osteoconductive effect.
 

Implant Surface in Bone Grafts

The type of implant surface texture (rough-surface including HA-coated & TPS implants) and material appears to be an important variable in the bone graft setting. This indicates that in grafted bone these surfaces may have a greater capacity to osseointegrate. 
 
Jensen et al.1996. Report of the sinus consensus conference of 1996. JOMI.vol. 13. 1998.
In the nongrafted setting , rough surfaces have been shown to result in greater bone contact and greater torque removal capacity in the human tibia.
Carlsson L. et al. 1994. Bone response to HA-coated and commercially pure titanium implants in the human arthritic knee J Orthop Res 1994.
The chemical nature of the biomaterial surface may also be the result of its increased capacity to bridge small gaps between the implant surface and the bone graft (up to 1mm), whereas machined titanium bridges osseous gaps of only 0.25 mm consistently to form intimate, early contact and then osseointegration.
 
Jensen JA. et al. 1993. A histological evaluation of the effect of HA-coating on interfacial
response. J Mater Sci Mater Med 1993.
However, there is yet no evidence to determine if rough surfaces are > favored in the bone-graft setting and data regarding comparative success rates of the different implant surface is required.
Carlsson L. et al. 1988. Implant fixation improved by close fit :
Cylindrical implant-bone interface studied in rabbits. Acta Orthop Scand 1988.
 

Sinusis consensus conference of 1996 

(O T. Jensen et al.1996.JOMI.vol. 13. 1998)
  • Retrospective data from sinus floor augmentation bone grafts were collected from 38 surgeons for 1007 sinus grafts that involved the placement of 2997 implants over a 10-year period with the majority of implants followed for 3 years or more post-restoration.
  • 229 implant failures reported with 90% success rate of implants placed in sinus grafts with at least 3 years of function. 
  • Controlled prospective?)
  • Multivariative / multifactorial database!
Consensus: Sinus graft should now be considered a highly predictable and effective therapeutic modality.  
Sinus graft (sinus lift), introduced by Tatum (1986) and Boyne & James (1980)
  • 61% implant failure when there was a 5mm or less of the presurgical bone present.
  • 61% implant failure when implants were placed simultaneously with sinus bone grafting. 
  • Smoking was reported as a factor In 50 (31%) of the 164 implant failures.
  • Ethanol abuse was considered a factor in 4 (3%) implant losses.
  • End-stage peri-implantitis occurred in 49 implants (18 machined titanium, 36 HA-coated, 5 TPS).
  • The overall success rate for delayed placed implants was 83.9% and 85.5& in the simultaneous group, statistically no differences.
  •  
  • Regardless of harvest site, grafts did somewhat better with the delayed approach (87.4%) than with the simultaneous approach (79.1%)


Surgical procedure

Sinus spaces are cavities in the upper jaw (Maxilla) on each side of the nose and above your upper back teeth. Specially treated donor bone is placed into these empty areas. Over a period of time this is replaced by new bone thus providing a bed into which implants can be fixed. 
Whatever type of bone is added o the sinus it must be left to mature before implants are placed or brought into function. Implants can be inserted after four to nine months, although occasionally it may be necessary to wait longer.
As with other one grafting procedures, the implants are left to become firmly attached to bone. Commonly a slightly extended healing period is chosen with an average of six to nine months before a denture or crown and bridgework is fitted. However, all bone grafting is unique to each individual and this information is for guidance only.s


Risks and Complications:

At the time of the procedure: If any infection is found or a tear in the lining of the sinus occurs it may be necessary to discontinue the procedure. 


Immediately after surgery

  • The post-operative symptoms are unpredictable and varying in different patients.
  • The occurrence of severe complications is extremely rare but most patients will have some swelling and a minority bruising and some may have temporary closure of the eys. 
  • Occasionally mild nose bleedings may occur. 
  • You may not to work for a few days. 
  • Later complications: 
  • The possibility of infections of the sinus post-operatively is very low. 
  • If this does occur and the infection continues after antibiotic treatment, it may be necessary to clean the sinus graft out. A rare complication is the development of a small hole from the sinus into the mouth. This can be treated.


Post-operative care

  • Avoid blowing your nose for 2 weeks
  • Sneeze through your mouth
  • Avoid swimming or flying
  • Report nose bleeds or sinus pain or swelling immediately
  • Swelling is often worse by the 2ndor 3rdday and may persist for a few days. If persists more tha a week then contact the surgery immediately.
  • Soft diet during the first days
  • Rinse X3/Day with Corsodyl (0.2%) and GENGIGEL mouth wash
  • Consume your antibiotic if/as recommended  (please read the instruction inside the package)