A new morphologic classification of the alveolar ridge after distraction osteogenesis in human patients. A 17 years retrospective case series study.

BACKGROUND To perform a morphologic classification based on the results of bone augmentation after a distraction osteogenesis. MATERIAL AND METHODS Thirty-four (34) patients (24 women and 10 men; mean age, 47.1 years (SD=9.5); age range, 23 to 62 years) underwent a total of 42 alveolar ridge distractions before the placement of a total of 89 dental implants. Ridge bone morphology was evaluated as the main ordinal variable. Chi-squared, Kruskal-Wallis and ANOVA one-way test were used. RESULTS Category I (30.95%): consisted of wide alveolar rim and no bone defects Category II (28.57%): wide alveolar rim, lateral bone surface concavity. Category III (23.81%): narrow alveolar rim, lateral bone surface concavity. Category IV (2.38 %): distraction transport segment forming a bridge, without bone formed beneath and requiring guided bone regeneration. Category V (9.52%): return of the transport segment to its initial position due to the reverse rotation of the distractor screw. Category VI (4.76 %): distraction transport segment completely lost. Subcategory D (28.57%), consisted of lingual deviation of the distraction axis, occurring in any of the categories I to IV. More men (76.9 %) presented with category I (p<0.001). The use of the chisel resulted mainly in categories I and II (69.4 %) (p<0.001). GBR was only required in 23.1 % of the cases in Category I (p=0.011). The bone height achieved decreases as the category increases, due to the accompanying osteogenic limitations (p<0.001). The implants placed in category I were longer 11.5 ± 0.9 mm (CI95% 10.9-11.9 mm) compared to those placed in category III with a length of 10.4 ± 1.5 mm (CI95% 9.5-11.4 mm) (p=0.035). CONCLUSIONS The alveolar ridge after distraction osteogenesis could be divided into six morphologic categories which provide a useful basis for decision-making regarding implant placement.