Main aim of this study was to assess survival rates of short implants with a length of 4 mm in the edentulous mandible after 1, 3, and 5 years.

It is hypothesized that survival rates after 1, 3, and 5 years of Straumann Roxolid® / SLActive® 4 mm short implants do not differ from values of Straumann SLActive implants with more than 4 mm length in the same clinical situation.

Inclusion Criteria:

General criteria:

• Age: 18 to 70
• Edentulous mandible with reduced bone level in the posterior region (> 5 mm and < 8 mm above nerve conduit)
• Physical and mental condition that allow surgery and a 5-year follow-up period to be carried out without foreseeable problems
• Obtained informed consent from the patient

Specific criteria:

• Limited vertical space for implant placement, where conventional implants with lengths of more than 4 mm cannot be used
• Tooth loss or extraction at least 8 weeks before implant surgery
• Healthy implantation site
• Favorable and stable occlusal relationship
• Complete denture in the mandible. If no denture available, an interims prosthesis will be fitted
• Natural full dentition or sufficient complete or partial dentures in the maxilla

Exclusion Criteria:

General criteria:

• Any conditions or circumstances which would interfere with the requirements for oral surgery
• Allergy to any metallic implant component
• Acute, untreated periodontitis
• Previous oro-maxillo-facial radiotherapy
• Any disorders in the planned implant area such as previous tumors or chronic bone disease (e.g., rheumatoid disease)
• Any ongoing application of interfering medication (steroid therapy, bisphosphonate, etc.)
• Alcohol or drug abuse
• Heavy smoking (>10 cigarettes/day)
• Uncontrolled diabetes
• Severe bruxism or other destructive oral habits
• Pregnant or lactating women

Specific criteria:

• Need for a major bone regeneration technique
• Infections in adjacent tissue of the planned implantation site.
• Bleeding on probing (BOP) and plaque index (PI) higher 25%
• Insufficient bone volume in the posterior region for placing a Straumann Roxolid® / SLActive® 4mm short implant and in the interforaminal region for placing a Straumann Roxolid® / SLActive® implant with a minimum length of 10 mm determined by radiographic analysis (OPG)

Dental patients of university-based prosthodontic department (primary, secondary, and tertiary care clinic)