The primary objective is the area of newly formed bone (%) as assessed by histomorphometry with either MD05 or beta-TCP.

Inclusion Criteria:

• Patients requiring two-stage unilateral maxillary sinus floor augmentation (sinus lift) in case of insufficient bone height in the area of the posterior maxilla, prior to insertion of dental implants
• Residual bone height at the site of planned implantation > 1 mm and < 5 mm
• Male and female outpatients, 18 to 75 years old
• Female patients must be infertile (either sterilized or postmenopausal). If a patient's menopausal status at screening is uncertain, levels of follicle stimulating hormone (FSH) should be determined. Patients with an FSH level > 25 IU/l and absence of menstrual bleeding > 6 months will satisfy the definition of postmenopausal status.
• Patient has given informed consent.

Exclusion Criteria:

• Women of childbearing potential, lactating women
• Participation in another clinical study within 30 days prior to study start
• Previous participation in this study
• Last dental extraction (maxilla, posterior to canine) within the last 3 months
• Failed sinus lift surgery and previous eradictive maxillary sinus surgery
• Simultaneously bilateral sinus lift
• Legal incompetence or restricted legal competence
• Alcoholism, drug dependency, smoking
• Acute or chronic infection at the application site, e.g., sinusitis
• Known infection with human immunodeficiency virus (HIV), hepatitis B virus (HBV), or hepatitis C virus (HCV)
• Severe allergic rhinitis which requires permanent medication (Rosenlicht 1999)
• Known intolerance of or hypersensitivity to beta-TCP or rhGDF﷓-5
• Presence of local or systemic malignant disease or history of local or systemic malignant disease in the past 5 years
• Patients requiring chemo- or radiotherapy
• Previous or current radiotherapy of the head
• Chronic liver disorder
• Impaired renal function
• Uncontrolled, insulin-dependent diabetes mellitus
• Clinically relevant symptoms of thyroid dysfunction
• Severe hypertension (RRdiast > 110 mmHg);
• Clinically relevant cardiovascular disease
• Systemic bone disease or illness having influence on bone metabolism,
• Clinically relevant blood coagulation disorder,
• Leukopenia < 3.500 leukocytes/µL
• Previous or current treatment with systemic corticosteroids
• Previous or current therapy with drugs having any influence on bone metabolism
• Previous or current treatment with immunosuppressant medication