Influence of Anatomy of Maxillary Sinus on New Bone Formation After Transcrestal Augmentation Procedures

Bone resorption and sinus pneumatization, following tooth extraction, are common occurrences in the posterior maxilla. They may cause both a quantitative reduction and qualitative deterioration of bone, resulting in an inadequate bone volume for a standard implant placement. Sinus floor elevation with lateral approach had been described 35 years ago and widely studied afterwards, demonstrating an high predictability in regenerating bone, to allow for reliable implant supported rehabilitations. Maxillary sinus floor elevation with transcrestal approach represents a validated and effective alternative option to vertically enhance the available bone through an access created in the edentulous bone crest. Regardless of graft type, it is not yet well defined how three-dimensional anatomical sinus cavity characteristics may influence healing and mineralization process. An adequate Schneiderian membrane elevation in order to expose sinus floor, buccal and medial walls, seems to represent a crucial factor in influencing new bone formation, as the greatest part of the osteoprogenitor cells derives from these anatomical structures. It is not documented yet the efficacy of the different trnanscrestal sinus floor elevation approaches in exposing the internal bony walls of the sinus. Moreover, on the basis of the fact that only few articles correlated the size of the maxillary sinus with histologic outcome by lateral window and one retrospective radiographic study reported results in relation to the three-dimensional conformation of the sinus using a trans-crestal approach, the investigators conjecture that sinus bucco-palatal diameter could influence the newly-formed bone quality after a crestal sinus lift procedure. For example, the healing in a narrow maxillary sinus could result in a faster new bone formation, when compared to a larger and wider sinus. The aim of this study is to analyze neoformed bone after maxillary sinus lifting with transcrestal approach, in atrophic crests (≤5 mm residual bone height). Clinical and laboratory data will be related to maxillo breast anatomy. The present study has been designed as a multicenter prospective clinical trial. Five clinical centers will treat patients with two-stage transcrestal sinus floor elevation using a calibrated drills technique and a xenogeneic biomaterial. Implants will be inserted 6 months after sinus augmentation and bone-core biopsies will be harvested during the implant site preparation. Histological analyses will be performed in order to assess the quality of the newly-formed tissue and cone beam computed tomography scan examination will be used to evaluate graft resorption over time. For each inserted implant, collection of experimental parameters will be required up to 1 year after its placement.

• transcrestal sinus floor elevation (Procedure), also known as implant insertion: augmentation procedure with xenograft

Primary outcomes

• newly formed bone [6 months after surgery]: assessment of newly formed bone via histomorphometric analysis

Secondary outcomes

• implant success [1 years after implant insertion]: short term implant success rate via clinical and radiographic data
• exposed walls [10 day after surgery]: number of sinuses exposed walls after augmentation procedure via cone beam computed tomography

Sex: All, ages: 18 Years to any

Inclusion Criteria:

Local inclusion criteria will be the following:

* indications for a transcrestal sinus floor augmentation to allow for a single implant placement, based on accurate diagnosis and treatment planning;
* presence of a residual bone crest with a height ≤3 mm on the maxillary sinus in the site where implant placement is programmed;
* the bone crest must be healed (at least three months elapsed after tooth loss);
* age of the patient >18 years;
* patient willing and fully capable to comply with the study protocol;
* written informed consent given.

General exclusion criteria are:

* acute myocardial infarction within the past 2 months;
* uncontrolled coagulation disorders;
* uncontrolled diabetes (HBA1c > 7.5%);
* radiotherapy to the head/neck district within the past 24 months;
* immunocompromised patient (HIV infection or chemotherapy within the past 5 years);
* present or past treatment with intravenous bisphosphonates;
* psychological or psychiatric problems;
* alcohol or drugs abuse.

Exclusion Criteria:

* Local exclusion criterion is the presence of uncontrolled or untreated periodontal disease.

• Farina R, Pramstraller M, Franceschetti G, Pramstraller C, Trombelli L. Alveolar ridge dimensions in maxillary posterior sextants: a retrospective comparative study of dentate and edentulous sites using computerized tomography data. Clin Oral Implants Res. 2011 Oct;22(10):1138-1144. doi: 10.1111/j.1600-0501.2010.02087.x. Epub 2011 Feb 15. PMID 21320169
• Esposito M, Grusovin MG, Rees J, Karasoulos D, Felice P, Alissa R, Worthington H, Coulthard P. Effectiveness of sinus lift procedures for dental implant rehabilitation: a Cochrane systematic review. Eur J Oral Implantol. 2010 Spring;3(1):7-26. PMID 20467595
• Avila G, Wang HL, Galindo-Moreno P, Misch CE, Bagramian RA, Rudek I, Benavides E, Moreno-Riestra I, Braun T, Neiva R. The influence of the bucco-palatal distance on sinus augmentation outcomes. J Periodontol. 2010 Jul;81(7):1041-50. doi: 10.1902/jop.2010.090686. PMID 20450402
• Results publication: Lombardi T, Stacchi C, Berton F, Traini T, Torelli L, Di Lenarda R. Influence of Maxillary Sinus Width on New Bone Formation After Transcrestal Sinus Floor Elevation: A Proof-of-Concept Prospective Cohort Study. Implant Dent. 2017 Apr;26(2):209-216. doi: 10.1097/ID.0000000000000554. PMID 28125520

• Claudio Stacchi, Dr., Principal investigator, Piezosurgery Academy