Prefgel

The simplified papilla preservation flap technique (SPPF) [47 ] was used in case of an interdental width of ≤2 mm, as measured at the papilla base. A modified papilla preservation flap (MPPF) [48 (link)] was performed at sites presenting with an interdental width of >2 mm. Vertical releasing incisions were avoided. After flap elevation, thorough debridement of the root surface, and degranulation, the defect was rinsed with sterile saline. A 24% ethylenediamine tetraacetic acid gel (PrefGel, Institut Straumann AG, Basel, Switzerland) was applied to the exposed root surface and removed after 2 min using saline. Then, EMD (Emdogain, Institut Straumann AG, Basel, Switzerland) was administered to the root surface. The bone defect was filled with a granular bone substitute (biphasic calcium phosphate (BCP); Bone Ceramic, Institut Straumann AG, Basel, Switzerland) mixed with EMD, using a sterile amalgam gun. BCP was not only applied into the bone defect for flap support, but also used for vertical augmentation beyond the remaining defect margins in order to compensate for both vertical and horizontal bone loss and to re-establish the physiologic convex inter-proximal bone contour (Figure 5A,B). Then, the flaps were closed with modified vertical mattress sutures, using fine monofilament suture material (6.0). Sutures were removed after two weeks.

At the end of the instrumentation, the defect was rinsed with sterile saline and EDTA (sterile 24% EDTA gel, pH 6.7; PrefGel, Straumann, Basel, Switzerland) was applied on the instrumented root surface for 2 min. The defect area was then carefully rinsed with saline and a thin layer of cross-linked HA gel (HYADENT BG^®, BioScience, Germany: a gel formulation containing cross-linked HA (1000 kDA HA monomers) and non-cross-linked HA (2500 kDA) in a ratio 8:1, made from biotechnologically produced synthetic HA) was applied on the root surface. Afterwards a 1:1 ratio mixture of HA and deproteinized porcine bone mineral (THE Graft, Purgo Biologics Inc., Korea) was gently packed into the intrabony defect to the level of the bone, not overfilling the defect. The flaps were repositioned and primary wound closure was achieved with a horizontal internal mattress suture at the base of the papilla and a single interrupted suture to connect the tips of the papillae. The papillae were sutured using the monofilament non-resorbable 5-0/6-0 suturing material (Ethilon‚ Ethicon, Johnson and Johnson, Somerville, NJ, USA) (Figure 1 and Figure 2).