Unprotected autogenous bone block grafts in the anterior maxilla: Resorption rates and clinical outcomes

Abstract

Background/Aim. The use of autogenous bone grafts for augmentation of the resorbed alveolar ridge is still considered the gold standard in implant dentistry. The aim of this study was to analyze the resorption rate of autogenous bone block grafts from the retromolar region placed in the frontal segment of the upper jaw unprotected by barrier membranes, to assess the stability of implants placed into the grafted bone, as well as to monitor its changes during the healing period. Methods. The study included 18 patients with a total of 20 grafted sites. The residual alveolar ridge was measured before and after the augmentation and prior to implant placement. All implants were restored with provisional crowns within 48 hours after the placement. Implant stability was assessed using resonance frequency analysis. Results. The average period from ridge augmentation to reentry was 5.4 months (range 4-6 months) . At reentry the healed alveolar ridge had a mean width of 6.1 ± 1.27 mm. The mean calculated width gain was 3.04 ± 1.22 mm. The overall surface resorption of block grafts was 0.68 ± 0.69 mm (18.85%). At the time of implant placement the mean value of implant stability quotient (ISQ) was 71.25 ± 5.77. The lowest ISQ values were noted after three weeks of healing, followed by a gradual increase until week 12. After 12 weeks implants showed significantly higher ISQ values compared to primary stability (p lt 0.05 Wilcoxon signed ranks test). During the 3-years followup period no cases of implant loss were recorded. Conclusion. Despite a significant resorption of bone grafts, it was possible to place implants in all the cases and to use the immediate loading protocol without affecting implant survival rate.

Uvod/cilj. Primena autogenih koštanih graftova (implantata) za uvećavanje smanjenog (resorbovanog) alvelarnog grebena još uvek se smatra zlatnim standardom u implantologiji. Cilj ove studije bio je analiza stepena resorpcije autolognih koštanih blok transplantata nezaštićenih barijernim mebranama, uzetih iz retromolarnog predela mandibule i postavljenih u frontalni segment gornje vilice, procena stabilnosti implantata ugrađenih u povećanu regiju, kao i praćenje promene implantne stabilnosti tokom perioda oseointegracije. Metode. U studiju je bilo uključeno 18 pacijenata sa ukupno 20 autotransplantata. Širina rezidualnog alveolarnog grebena merena je pre i posle postavljanja transplantata, kao i neposredno pre ugradnje implantata. Svi implantati su opterećeni privremenim nadoknadama 48 sati nakon ugradnje. Stabilnost implantata procenjivana je primenom analize rezonantne frekvencije. Rezultati. Srednje vreme između uvećavanja grebena i ugradnje implantata iznosilo je 5,4 (4-6) meseci. Pre ugradnje implantata srednja vrednost širine grebena iznosila je 6,1 ± 1,27 mm, a povećanja širine grebena u odnosu na vrednosti pre uvećanja 3,04 ± 1,22 mm. Površinska resoprcija grafta iznosila je 18,85% (0,68 ± 0,69 mm). Srednja vrednost koeficijenta implantne stabilnosti (ISQ) u momentu ugradnje iznosila je 71,25 ± 5,77. Najniže vrednosti ISQ zabeležene su u trećoj nedelji nakon ugradnje, što je bilo praćeno postepenim porastom do dvanaeste nedelje zarastanja. Nakon dvanaest nedelja vrednosti ISQ bile su statitički značajno više od vrednosti u momentu ugradnje (p lt 0,05 Wilcoxon test). Tokom trogodišnjeg perioda praćenja nije bilo izgubljenih implantata. Zaključak. Bez obzira na značajan stepen resorpcije autotransplantata, kod svih pacijenata bilo je moguće ugraditi implantate u uvećani greben, kao i primeniti protokol ranog opterećenja bez uticaja na stepen preživljavanja implantata.