Xenogenic Bone Intentionally Left Exposed
Condition: Soft Tissue; Dental Implants; Healing Wound
Study type: Observational

Summary: 
      The goal of this clinical trial is to compare, the effect of letting the xenogeneic bone
      graft exposed to the oral environment or seal off the graft with a collagen matrix. Them main
      questions it aims to answer are:

        -  The enhancement of soft tissue healing during the initial phases following immediate
           implant placement.

        -  The secondary aim is to evaluate the dimensional alterations in hard tissues at
           immediately placed implants and different biomaterial protocol.

      It were selected patients with indication of flapless extraction in posterior teeth, which
      was placed immediate implant (n=28) and gap filling with deproteinized bovine bone mineral
      (Geistlich Bio-Oss®). In this study, participants were stratified into two randomized blocks,
      each corresponding to a distinct surgical technique: left exposed the graft to the oral
      environment or coverage with a collagen matrix (Geistlich Mucograft®).

        -  Previously the extraction was performed the measurement of the keratinized gingiva, and
           after 04 months of implant placement.

        -  The soft tissue healing was evaluated on days 02, 07, 30 days; by means of a
           blue-stained solution (methylene blue 0.05%) and standardized photograph.

        -  In the same date from different healing times it was performed immunoenzymatic analysis
           of the levels of VEGF (vascular endothelial growth factor), IL-1β (interleukin-1β) and
           FGF2 (fibroblast growth factor 2).

        -  It was also be performed cone beam computed tomography images quantifying the soft and
           hard tissues thickness of the facial and lingual bone wall. The clinical trial examiner
           was blinded during the study period.
    

Detailed description: 
      The present study aimed to evaluate molecular, histologically and tomographic soft and hard
      tissue parameters of tissue healing in immediate placement of dental implant and gap filling
      with Bio-Oss covered (control group), or not (test group) with Mucograft. he hypothesis was
      that both the test group and the control group would have great results in alveolar
      preservation.

      The implant function successful does not reach the patients and clinicians aesthetic demands,
      as well the approach and integrity of hard and soft tissue structures, which are compromised
      by physiological and structural changes after the dental extraction, are challenge in the
      implant treatment (Chappuis et al., 2017). The alveolar process is tooth dependent, and the
      dimensional alterations of the alveolar ridge that occurred following tooth extraction in a
      thin bone phenotype (< 1 mm) is inherent in the healing process, but can be minimized by
      alveolar preservation (Ten Heggeler et al., 2011; Jung et al., 2013; Sculean et al., 2014;
      Chappuis et al., 2017; Jung et al., 2018). A systematic review revealed 2.6 to 4.5 mm in
      width bone loss and 0.4 to 3.9 mm vertically in non-molar regions following tooth extraction
      (Ten Heggeler et al., 2011). This loss could be reduced from 43.3% to 18.1% by using bone
      grafts and covering the alveolus with free gingival grafts in a 6-month follow-up (Jung et
      al., 2018). Several studies focused on bone healing parameters, placing bone substitute
      materials in alveolar sockets to reduce resorption after tooth extractions. However, soft
      tissue healing after extraction received little attention in clinical research.

      The average and standard deviation of group 1 were 4 and 0.8, respectively, and for group 2,
      they were 5 and 1. To verify the variation in amount of keratinized tissue considered
      clinically relevant and different between groups was calculated (GPower 3.1). A sample for a
      total of 28 immediate implant placement, being equivalent to each group (14 for group 1 and
      14 for group 2), taking into account a significance level of 5%, 80% test power and average
      difference of 1.0 mm between the groups and standard deviation of 20%. The study was a
      Randomized Controlled Clinical Trial, with clinical procedures conducted by an experienced
      dentist, and the examiner analyzing the entire trial blinded during the study period.

      The selection included patients requiring extraction of at least one posterior tooth due to
      caries, endodontic complications, periodontitis, orthodontic and prosthetic reasons. Only
      healthy patients with adequate oral hygiene (bleeding on probing ≤ 10% and plaque), primary
      stability of at least 35N after implant placement. The exclusion criteria were: age < 18
      years, smoking; smoking more than 10 cigarettes per day; presence of relevant medical
      conditions: diabetes mellitus, unstable or potentially fatal conditions or requiring
      antibiotic prophylaxis and drug medication that influence bone metabolism; pregnant or
      lactating women; radiotherapy or chemotherapy for malignancy in the last 5 years; history of
      autoimmune disease; presence of acute periodontal or periapical pathology; and history of
      drugs or elitist. . Patients were invited to participate after ethical committee approval,
      and randomization into blocks was done through an online application.

      A comprehensive periodontal examination was conducted before any surgical procedure.
      Keratinized gingiva width was evaluated using a periodontal probe at the facial level,
      measuring the distance from the muco-gingival junction and gingival margin before extraction
      and after 4 months at implant placement. Flapless tooth extraction was performed in the least
      traumatic way, and dental implants (Straumann SLActive) were immediately placed. The buccal
      gap was filled with xenogeneic deproteinized bovine bone (Geistlich Bio-Oss®). In the study
      group, bone grafting was exposed with flap healing by second intention, while in the control
      group the collagen matrix (Geistlich Mucograft®) was pulled over the healing cap. Standard
      postoperative instructions were given, and Amoxicillin 875 mg (every 12 hours for 11 days)
      was prescribed 24 hours before the surgical intervention, along with analgesics every 6 hours
      for 3 days.

      At each follow-up visit (02, 07, 30 days) the surgical area was stained with methylene blue
      (0,05%) to check for surface epithelialization. The lesions are stained so that they are
      easily distinguishable. This solution has been suggested to identification of minor areas
      lacking epithelium (Kohale et al., 2018). Tthe chosen dates corresponded to the stages of
      tissue healing: initial (0 - 3 days), revascularization (4-11 days), and maturation of tissue
      (11-42 days). Clinical measurements recorded on days 2, 7, and 30 postoperatively were
      photographed by occlusal view, and epithelium scores were evaluated, classified as follows
      (Jung et al., 2018): Grade 1: non-existent; Grade 2: covering less than one-quarter of the
      wound surface; Grade 3: covering less than half the wound surface; Grade 4: covering more
      than three-quarters of the wound surface; and Grade 5: normal or complete covering of the
      wound.

      The regulation of anti-inflammatory cytokines VEGF and IL-10, and pro-inflammatory IL-1β and
      TNF-α (tumor necrosis factor-α) are key factors in wound healing, in which the increase of
      these latter cytokines are indicative of delayed healing. VEGF is a vascular endothelial
      growth factor, being one of the main stimulators of the formation of new blood vessels
      (Sculean et al., 2014). Thus, in the immunoenzymatic analysis, the levels of VEGF, IL-1β and
      FGF2 were evaluated. Fluid samples from the wound were obtained by means of a stick with
      sterile swab, slow rolling movements, edge-to-edge, after little irrigation with sterile
      saline solution. Then the the swabs were placed in 2 mL microtubes and samples were frozen at
      -80° C until analyzed. Immunoenzymatic analysis was conducted to evaluate the levels of VEGF,
      IL-1β, and FGF2 in fluid samples obtained from the wound. Commercial kits and Luminex/MAGpix
      technique were used for quantitative cytokine levels determination from a fifth-degree
      polynomial curve using the xPONENT Software® (Luminex Corporation, Austin, TX, EUA).

      For the evaluation of bone thickness and soft tissues, cone beam computed tomography (CBCT)
      imaging was used. Patients used mouth retractors and were instructed to stay with the tongue
      retracted, directed to the palate, and it was possible to distinguish the soft tissues of the
      lips, cheeks and gums. The CBCT were acquired with the iCAT software on a computer. A scan
      was taken of the maxilla (scan dimensions of 6x17 cm) for 40 seconds with the following
      setting of the iCAT-voxel size: 0.2 mm; gray scale: 14 bits; focal spot: 0.5 mm; image
      detector: amorphous silicone flat panel; image acquisition: single 360° rotation. The scan
      was performed after surgery and in the fourth following month, evaluating bone thickness and
      gingival tissue. An open software package (Slicer 3.6. www.slicer.org) was used for the
      overlap of the original DICOM data of the two tomographies, evaluating bone thickness and
      gingival tissue. Thus, the two image sets were aligned and checked manually for perfect match
      (Jung et al., 2013). Reference lines were drawn based on the most apical point of the
      extraction outlet and the apex of the implant. The vertical reference line was drawn at the
      center of the extraction outlet crossing the apical reference point. The horizontal reference
      line was drawn perpendicularly to the vertical line crossing the apical reference point.
      Standardized measurements evaluated horizontal bone thickness, both vestibular and lingual,
      from traces delimited 2 mm below the implant machined collar (reference line - RL), RL, -2,
      -1 and 0 mm above this line. Soft tissue thickness was evaluated at baseline and alterations
      after 4 months.
    

Intervention name(s): Bio-Oss Exposed; Mucograft Exposed
Intervention type(s): Procedure; Procedure
Intervention description(s): Molar extraction with a flapless approach and immediate implant installation, filling the gap with deproteinized bovine bone mineral (Geistlich Bio-Oss) and left exposed to the oral environment.; Molar extraction with a flapless approach and immediate implant installation, filling the gap with deproteinized bovine bone mineral (Bio-Oss; Geistlich) and covered by a collagen matrix (Mucograft; Geistlich).
Other intervention name(s): Immediate Implant Placement Associated with biomaterials; Immediate Implant Placement Associated with biomaterials
Observational model: Case-Control
Time perspective: Prospective
Sampling method: Probability Sample
Study population: 
        Patients with hopeless molar teeth who are scheduled for immediate implant placement in
        this area, in the researcher's town.
      
Keywords: Molar site; Alveolar Bone Loss; Tissue Conditioning, Dental; Biomaterials