This issue, edited by Dr. Frank Scannapieco, is devoted to "Unanswered Questions in Periodontology." Review articles will help answer clinical questions such as: Can lost bone in furcations be regenerated?; What biomarkers exist to detect active periodontal disease?; Which mouthrinse products are beneficial for plaque control and gingival health?; Do mobility and occlusal trauma impact periodontal longevity?; Can peri-implantitis be treated?; Is there a genetic basis for periodontitis?; What is the minimal sample size for studies of periodontal treatment?; Does treatment of periodontal disease influence systemic disease?; Does periodontal disease cause cancer?; Is the use of photodynamic therapy beneficial to conventional mechanical therapy in the treatment of periodontitis and peri-implantitis?; Are radiographs the best modality to diagnose and monitor periodontitis?; Does gingival recession require surgical treatment?; and Should antibiotics be prescribed to treat chronic periodontitis?

Articles include: Current Rationale for Treatment of Periodontitis, Effects of Periodontal Treatment on Systemic Health, Non-Surgical Mechanical Treatment Strategies, Use of Lasers to Treat Periodontal Diseases, Regeneration of Periodontal Tissues: Bone Grafts, Implants and Periodontal Patient, Regeneration of Periodontal Tissues: Growth Factors and Bone Morphogenetic Protein, Treatment of Gingival Recession, Non-surgical Chemotherapeutic Treatment Strategies, Regeneration of Periodontal Tissues: Guided, Future Approaches in Periodontal Therapy: Gene Therapy, RNA Interference and Stem Cells, and Restorative Trends for the Periodontal Patient.