Gli impianti nei deficit ossei verticali della mandibola. Due possibili soluzioni
La riabilitazione implantoprotesica dei settori posteriori atrofici della mandibola ( e parliamo nello specifico dei deficit ossei verticali) rappresenta spesso una sfida per il chirurgo implantologo, il canale mandibolare con il fascio vascolo nervoso aveolare inferiore rappresenta un limite anatomico inviolabile del quale bisogna tener conto in fase di progettazione e pianificazione chirurgica.
Presentiamo due possibili soluzioni riabilitative che possono essere adottate, la prima prevede l’utilizzo di impianti corti (short implants), la seconda invece contempla, prima dell’intervento per l’inserimento di impianti di lunghezza standard, il ricorso ad un intervento di chirurgia rigenerativa preimplantare condotto secondo la metodica definita “inlay tecnique”, si tratta di una osteotomia mandibolare a blocco ( o “a cassetto”) con sollevamento del segmento più coronale ed interposizione di un innesto di osso di derivazione animale in blocco più materiale particolato.
Entrambe le metodiche consentono, secondo la nostra personale esperienza, di ottenere buoni risultati.
Ciascuna metodica presenta vantaggi, svantaggi, limiti, indicazioni e controindicazioni specifiche.
Naturalmente esistono anche altre possibilità di riabilitazione implantoprotesica che posson esser adottate in caso di atrofia mandibolare posteriore, ciascun chirurgo sceglierà l’approccio che riterrà più idoneo alla soluzione del caso che gli si prospetta sulla base di quelle che sono la sua esperienza, cultura e le sue convinzioni personali, sempre e comunque con l’obiettivo unico di venire incontro alle esigenze e alle aspettative del paziente.
Seguono gli abstract (in lingua inglese) di 2 lavori scientifici presentati alla XVII e XVIII edizione del Congresso Nazionale dei Docenti di Discipline Odontostomatologiche e pubblicati su Minerva Stomatologica.
Use of short implants in atrophic mandible
E. Di Iorio, L.M. Sacco, A. Scarano
Department of Odontostomatologic Science, University of Chieti-Pescara, Italy
Aim: In the last decade, several investigators have reported that short implants achieved excellent results with a two-stage technique. Implant prostheses are often used to restore partially or completely edentulous patients, but limited bone height, especially in the posterior mandible, may restrict the use of dental implants. Short implants may be selected in these situations. They have several advantages: it is possible to reduce the need for sophisticated and expensive surgical procedures like sinus lift, bone grafting and mandibular nerve transposition, it is possible to place short-span dentures and it is possible to avoid cantilevers in the posterior regions. The purpose of this study was to test the hypothesis that short implants in prosthetic rehabilitation of atrophied jaws might give similar long-term implant survival rates as longer implants used in larger bone volumes.
Materials and methods: from March 2007 to January 2010, 9 healthy patients ( 6 women and 3 men, age range 45–68 years ) were included in this study. A total of 24 titanium short implants 4,5 X 6 mm ( P.H.I., S.Vittore Olona, Milano, Italy ) were inserted in atrophic mandible.
Results: One implant was removed for mobility after the loading. The overall survival rate of implants placed was 95,83%.
Discussion: Short-length implants should be at a performance disadvantage because of the more limited surface area with which to resist occlusal forces. Nevertheless, anecdotal observations find many short implants performing well in different restorative conditions. Although the predictability of endosseous dental implants is well documented, the restoration of the posterior region of the jaws remains a challenge. The placement of short implants is one therapeutic option that reduces the need for augmentation therapy. This study demonstrates that the use of short implants maybe considered for prosthetic rehabilitation of the severely resorbed jaws as an alternative to more complicated surgical techniques.
Conclusions: Short implants are used in case of reduced bone height as they avoid the need for additional surgical procedures for bone augmentation or mandibular nerve transposition. The overall success rate compares favorably with the available litterature for the performance of implants in general, and short implants in particular. In conclusion short implants can be a solution in cases of limited bone height.
MINERVA STOMATOLOGICA – Volume 59 – Supplemento 1 al N.4 – Aprile 2010. Pag. 56
Vertical ridge augmentation of atrophic posterior mandible using an inlay technique with a xenograft without miniscrews and miniplates
E. Di Iorio, G. Iezzi, C. Mancino, A. Di Cristinzi, A. Scarano
University "G. D' Annunzio" Chieti-Pescara
Limited bone height in the posterior mandible can be treated with surgical procedures for bone augmentation. Purpose of this study was evaluate an inlay technique without the use of miniscrews and miniplates for stabilization of the transported bone fragments. The use of miniscrews and miniplates have been reported to increase the risk of fracture of the osteotomy segments. Nine patients were enrolled in this study. A horizontal osteotomy was performed 2-3 mm above the mandibular canal, and two oblique cuts were made using a piezosurgery device and chisels.
The osteotomized segment was then raised in the coronal direction, sparing the lingual periosteum. Two miniblocks of xenograft (equine collagenated bone) without miniscrews and miniplates were inserted mesially and distally between the cranial osteotomized segment and the mandibular basal bone. The residual space was filled by particles of porcine bone. Four months later a bone trephine was used to take a bone core biopsy during preparation of the implant sites.
Newly formed bone was seen in close contact with the particles of biomaterials. No gaps or connective tissue were present at the bone-biomaterial interface. Histomorphometry demonstrated that 44±2.1% of the specimen was composed by newly formed bone, 18±0.8% by marrow spaces, and 33±2.4% by the residual grafted biomaterial. The rigidity of the equine collagenated bone allowed to eliminate the use of miniscrews and miniplates and allowed maintenance of the space.
MINERVA STOMATOLOGICA - VOL. 60 - SUPPLEMENTO 1 - AL N. 4 (APRILE 2011)