Bone tissue engineering is a promising approach for treatment of defective and lost bone in the maxillofacial region. Creating functional tissue for load bearing bone reconstruction using biocompatible and biodegradable scaffolds seeded with living cells is of crucial importance. The aim of our study was to compare the effects of poly-lactic-co-glycolic acid (PLGA) and hydroxyapatite (HA) ceramic granulae on growth, differentiation, mineralization and gene expression of mandibular mesenchymal cambial layer precursor cells (MCLPCs) cultured onto tissue engineered three-dimensional (3-D) composites in vitro. These 3-D composites were cultivated in a rotating cultivation system under osteogenic differentiation conditions for a maximum period of 21 days. After 6 and 21 days, histological examination was performed; scanning electron microscopy (SEM), alkaline phosphatase (ALP) activity and levels of DNA were investigated. Expression of bone-specific genes osteocalcin, osteonectin, osteopontin, ALP, core binding factor alpha 1 and collagen type I were investigated by using a reverse transcription-polymerase chain reaction (RT-PCR) method. After 6 and 21 days of incubation an initiation of mineralization and the presence of newly formed bone at the surface of the composites were shown after evaluation of ALP activity, DNA content, SEM and histological staining. Expression of bone-specific genes confirmed the bone-like character of these composites and different effects of PLGA or HA granulae on the osteogenic differentiation of human MCLPCs in vitro. The results of this study support the concept that substrate signals significantly influence MCLPCs growth, differentiation, mineralization and gene expression in vitro, and that the use of these cells in the manufacturing of 3-D cell/HA composites is a promising approach for load bearing bone reconstruction in the maxillofacial region in vivo.