ABSTRACT:

Dental Implants are one of the best alternatives to lost dentition be it partial or complete. It provides one of the most comfortable replacement for the lost oral function with best patient satisfaction and oral rehabilitation, but certain anatomical limitations like low quality bone, pnuematized sinuses and loss of excessive basal bone act as limitations for successful Implant placement and functioning. With the advent of techniques and science,sinus lifting and grafting is now a boon in modern dentistry which allows to improve the quality of bone and has almost eliminated implant failures . Nevertheless less invasive noval techniques of sinus lifting like balloon sinus lift and peizoelectrics have overcome the risk of membrane rupture as complication which was most feared by many clinicians who can now proceed with sinus lifting without any fear of complications.

Introduction:

Poor oral function and detriment to self-esteem can debilitate millions of people who are partially or totally edentulous. Denture Prosthesis, which are often used to treat this condition, may not completely restore function because of poor fit related to alveolar ridge atrophy. As a result, dental implants have been developed to improve aesthetics and the function of mastication. These implants are surgically placed in the jaw to support a dental prosthesis. Dental implants provide an alternative to the standard removable complete or partial dentures and improve function almost completely. To be a candidate for the dental implant procedure, a patient must have sufficient bone in the maxillary and mandibular alveoli to support these fixtures. Unfortunately, after a prolonged period of being edentulous, the alveolar ridge that once supported the teeth becomes atrophic and sufficient bone may not be present for implant fixture placement. To increase the amount of bone in the maxilla, the sinus lift procedure or subantral augmentation, has been developed. This procedure involves placing bone-graft material in the maxillary sinus to increase the height and width of the alveolus¹.

A sinus-lift procedure is a surgical procedure, performed by an appropriately trained dental surgeon or dental specialist, to augment bone mass in the maxilla which increases the likelihood of successful placement of dental implants. Bone from another part of the body, such as the iliac crest, or artificial bone grafting material is grafted into the bone (endosseous) below the floor of the maxillary sinus. In the maxilla the amount of bone is reduced by the presence of the sinus².

Why should the membrane be lifted?

• Advantage of membrane elevation is that if there is laceration of the sinus membrane, the freeing up of the mucosa will allow membrane to collapse over the lacerated portion of soft tissue and facilitates healing.
• If not elevated, membrane tends to be taut, and laceration or opening will tend to persist because of tightness of the membrane¹.

INDICATIONS¹,³
1. Loss of alveolar bone height as a result of Periodontal disease prior to tooth loss.
2. Pneumatization
3. Poor Bone Density (Bone mineral density α contact between implants & bone surface.)
4. Strong Occlusal Forces.

TECHNIQUES

• The Osteotome approach⁴
• Hydraulic Sinus Condensing⁵
• Peizo surgery or Lasers⁶
• Balloon sinus lifting⁷

Osteotome Technique ³,⁴,⁸
Was developed to compress soft maxillary bone. Improved initial fixation obtained from bone compression of the osteotomy walls leads to better primary stabilization. Healing is rapid and uneventful. It involves inserting a series of osteotomes of successful larger diameter until full depth is reached, if possible. Surgeon positions and guides the instrument with both hands – one hand creates a rest and maintains stability while the other hand gently rotates and applies pressure with the osteotome .The assistant will apply gentle malleting technique to the osteotome. Osteotome is rotated after every stroke to prevent binding to the bone. Osteotomes are to be kept lubricated but irrigation is not required.

Summers technique with a crestal approach⁴

The site for implant is accomplished initially with a special, 3mm. long, pilot drill. A special, 3mm. long, intermediate drill is used now to prepare the site for the lifting drill. A lifting drill is inserted as long as the actual height of the ridge measured on the X-Ray. The grafting material is prepared and pushed up into the implant site with the body trying .Consequential fillings are then performed till the desired lifting Insertion of the screw implant or the cilindrical HA-coated implant.

Staged Sinus Floor Elevation¹,⁸

A technique for sinus floor augmentation with delayed implant placement introduced by Tatum in 1977. Large sized osteotome is used to infracture the crest after limited use of drills or trephines. Grafting is done without disturbing the sinus membrane. A collagen membrane is used to close the sinus membrane. The crestal entry creates a “socket” that heals rapidly. Implant fixture is placed 6 months later.

Lateral Wall Approach for Sinus Elevation / Simultaneous Sinus Elevation and Implant Placement

It is used for both delayed and simultaneous implant placement. Autogenous bone is harvested from the lateral wall of the antrum for use in conjunction with the allograft. The full extent of the sinus wall is made visible by thinning out of the lateral wall.Osteotomy is performed using a multifluted finishing bur. Infracture and membrane elevation are accomplished and the graft procedure is performed.

Advantages in lateral approach

Excludes nonosteogenic connective tissue, contains particulate graft material, prevents soft tissue growth, increases vital bone formation, increases implant survival rate, and results in positive outcomes when used for perforation repairs.

Hydraulic Sinus Condensing (HSC) ⁵

Hydraulic Sinus Condensing (HSC) is a sinus lift procedure invented in 1995, by Dr. Leon Chen of the Dental Implant Institute. Unlike the traditional methods of sinus lifts, which typically use an osteotomy of the lateral aspect of the maxilla, the HSC technique uses an osteotomy on the lateral aspect of the crestal ridge of the maxilla.

The Piezoelectric Bony Window Osteotomy and Sinus Membrane Elevation⁶

The piezoelectric bony window osteotomy easily cuts mineralized tissue without damaging the soft tissue, and the piezoelectric sinus membrane elevation separates the Schneiderian membrane without causing perforations. The elevation of the membrane from the sinus floor is performed using both piezoelectric elevators and the force of a physiologic solution subjected to piezoelectric cavitation, using the appropriate surgical device (Mectron Piezosurgery System). Micrometric cutting actions are produced by microvibrations, 20-60 µm in width bat a frequency of 29 KHZ, able to cut mineralized structures but remain completely inactive on soft tissues.

Balloon sinus lift⁷
Implant site preparation is done using 2mm pilot drill, followed by 2.8mm drill to reach upto 1mm short of the sinus floor, the sinus floor was gently elevated using osteotomes ranging from 3.8mm to 4.3mm or 5.0mm. Integrity of sinus membrane was confirmed by Valsalva maneuver. Inflatable balloon (Hager and Meisinger) is anchored and balloon slowly inflated with syringe filled with 0.9% saline, once desired elevation (>10mm) is achieved the balloon is deflated and removed.
Postoperative care⁹
Maintaining oral hygiene and using mouth wash is a must.
Prescribed Antibiotics must be taken as directed to help to prevent infection.
Patient is not supposed to blow the nose for the next four (4) weeks, not to sneeze holding the nose.
Not to drink with straws and not to spit.
Scuba diving and flying in pressurized aircraft should be avoided.
Avoid “Bearing down”—as when lifting heavy objects, blowing up balloons, playing musical instruments that require a blowing action or any other activity that increases nasal or oral pressure. 
Smoking must be stopped. 
Not to rinse or spit on the day of surgery.
Not to brush the teeth in the area of surgery for 48 hours.
Partial dentures, flippers, or full dentures should not be used immediately after surgery.

Complications⁷:
Sinus membrane perforation
Infection
Bleeding
Infra orbital nerve laceration
Postoperative discomfort like - Bleeding, discolouration, disability, hematoma and pain
Loss of incorporation of graft material

Summary and conclusion
Advances in sinus bone grafting have been interesting and exciting for prosthodontic reasons. Future areas of research oppurtunity for the development of improved methods of treating patients requiring implant therapy with significant maxillary deficiencies in need of osseous reconstruction as part of overall root form implant-supported prosthodontic rehabilitation. Where technologic innovation of sinus bone grafting will lead in future as the era of tissue engineering is entered, is to be seen. As rightly said by Aristotle, “All future inquiry must be based on critical observation and experimental validation”, Sinus lifting procedure is thus rightly proved to be a boon to patients who would otherwise never have dreamt of having implants placed because of the inherent deficiencies in bone quality and enlarged sinuses or would have to compromise retention with use of short implants.

References

1. Jenson OT: The Sinus Lift Procedures. 2nd Edition, Mosby Co.Chicago . Quintessence  2007
2. wikipedia
3. Misch CE: Contemporary Implant Dentistry. Mosby Co.3rd edn. 2008
4. Summers RB. Sinus floor elevation with osteotomes. J Esthet Dent 1998;10:164-71
5. Chen, L., Cha, J.: An 8-year retrospective study: 1,100 patients receiving 1,557 implants using the minimally invasive hydraulic sinus condensing technique. Journal of Periodontology 76(3):482-91, 2005 .
6. Myron Nevins, TomasoVercellotti, , Sergio De Paoli. The Piezoelectric Bony Window Osteotomy and Sinus Membrane elevation; Int J Periodontics Restorative Dent 2001;21:561–567.
7. Xiulian Hu, Ye Lin, Arnulf- Reimar Metzmacher, Yu Zang. Sinus membrane lifting using a water balloon- followed by bone grafting and implant placement: A 28 case report; Int J Prosthodont 2009;22:243-47.
8. Tatum H Jr.Maxillary and sinus implant reconstructions. Dent Clin North Am. 1986;30:207-29.
9. Dental Website