3D Printed Scaffold Device for Ridge Preservation After Tooth Extraction
Condition: Bone Resorption After Tooth Extraction
MeSH terms: Bone Resorption
Study type: Interventional

Summary: 
      Following tooth extraction, the socket heals naturally with bone in 1 to 2 months. This
      healing process occurs with substantial reduction of the original height and width of the
      alveolar ridge. In a significantly resorbed ridge, bone augmentation procedures are necessary
      before dental implant placement. Autogenous bone is the gold standard for this purpose but
      the harvesting procedure results in additional morbidities and expenses. Ridge preservation
      techniques have been introduced, using xenografts, allografts or synthetic materials to fill
      the tooth socket immediately after extraction. While the current materials used have improved
      ridge dimensions to various extents, their osteoconductivity is suboptimal and unpredictable.
      They do not reduce vertical resorption of the bony walls and often interfered with the normal
      healing process. Polycaprolactone - tricalcium phosphate (PCL-TCP) is a bioactive,
      bioresorbable composite polymer that is non-toxic and tissue-compatible. This study will test
      the use of a novel 3D printed PCL-TCP device for ridge preservation, leveraging on its 3D
      shape that fits snugly in the tooth socket, high porosity and bioactivity to promote
      osteogenesis and reduce resorption. The hypothesis is that the insertion of a PCL-TCP
      scaffold in extraction sockets allows normal bone healing and better maintenance of ridge
      dimensions after 6 months compared to extraction sockets without a space filler. This will be
      a prospective, randomized controlled clinical trial in patients who require single tooth
      extraction and replacement with a dental implant. The study will compare the ridge dimensions
      and the quality and quantity of bone formed in tooth sockets, using histology and
      microcomputed tomography, in both groups after 6 months. The PCL-TCP scaffold to be used in
      this study will be fabricated by a local spin-off company, Osteopore International Pte Ltd.
      The market potential for this device is tremendous due to a growing demand for tooth
      replacement from an ageing population worldwide.
    

Detailed description: 
      This will be a prospective, non-blinded randomized controlled clinical trial in adult
      patients who require single tooth extraction and who are suitable for dental implant therapy
      after extraction. The participants will be randomised by a clinician, using sealed envelopes
      that has been prepared by an independent party, to either the test or control group on a 1:1
      ratio:

      Test Group: insertion of PCL-TCP scaffold after tooth extraction Control Group: no space
      filler after tooth extraction

      Proposed study interventions 110 patients who give written consent to participating in the
      study will be recruited from the Departments of Oral & Maxillofacial Surgery and Restorative
      Dentistry at the NDCS.

      Patient may re-participate in the study for a different suitable teeth site. The
      re-participation(s) may take place on the same or a separate visit.

      Pre-extraction Preparation Dental models and standardised dental radiographs, including
      periapical and orthopantomogram, will be taken. A customised acrylic dental stent will be
      fabricated as a reference tool for standardised measurement of ridge dimensions. Three
      markings will be made (mesio-buccal, mid-buccal, disto-buccal) on the acrylic stent at the
      intended extraction site.

      Surgical Extraction and Socket Management

      Under local anesthesia, a trapezoidal buccal mucoperiosteal flap will be raised and an
      atraumatic extraction of the tooth will be performed. The tooth socket will be thoroughly
      debrided and any granulation tissue will be curetted out. The acrylic measuring stent will
      then be positioned by fitting it to the adjacent teeth and the following measurements will be
      taken using a periodontal probe (PCPUNC15; Hu-Friedy USA):

      Ridge height This will be measured indirectly as the vertical distance from each reference
      marking on the stent to the marginal bone of the tooth socket at the mesio-buccal, mid-buccal
      and disto-buccal aspects (Figure 1) and will recorded as RHmeb1, RHmib1 and RHdb1
      respectively.

      Ridge width This will be the horizontal distance from the buccal aspect to the lingual/
      palatal aspect of the alveolar crest at the mid-buccal region of the extraction socket (RW1).

      All measurements will be taken by 2 independent parties. Measurements that differ by less
      than or equal to 1mm will be averaged. Those that differ by more than 1mm will be repeated
      and a consensus will be reached by the parties. All measurements will be approximated to the
      nearest 0.5 mm.

      The extraction sockets will be managed differently for the test and control groups:

      Test Group

      PCL-TCP scaffold:

      The PCL-TCP scaffolds will be supplied by Osteopore International (Singapore). The scaffolds
      will be fabricated by the latest FDM techniques (FDM 3000; Stratasys, Eden Prairie, MN), in a
      class 10K clean room environment. Each scaffold will have a lay-down pattern of 0°/60°/120°,
      porosity of 70% and will be conical in shape. The scaffolds will a typical honeycomb
      structure with interconnected equilateral triangles of regular porous morphology. They will
      be individually packed and sterilized using gamma irradiation.

      One or more suitable size scaffold(s) will be chosen (small or large) based on the tooth to
      be extracted. During the surgery, the scaffold will be shaped by cutting and shaving with a
      scalpel so as to fit the extraction socket snugly at the crestal half to two-thirds aspect. A
      collagen membrane will be placed over the scaffold(s) at the crestal aspect of the socket.
      The periosteum of the buccal flap will then be incised to allow a tension-free primary
      closure with 4/0 Vicryl® suture.

      Control Group No space filler will be inserted in the extraction socket but similar to the
      test group, a collagen membrane will be placed over the crestal aspect of the socket and the
      periosteum of the buccal flap will be incised to allow a tension-free primary closure with
      4/0 Vicryl® suture.

      A periapical radiograph of the extraction site will be taken using standardised settings
      immediately postoperatively. A 5-day course of Amoxicillin (or Clindamycin if the patient is
      allergic to Penicillin) will be prescribed together with an analgesic and chlorhexidine
      digluconate 0.2% mouthrinse. The sutures will be removed 1 week postoperatively. The surgical
      site will be examined clinically for any signs of infection or wound dehiscence. A temporary
      denture will be issued where necessary. The denture overlying the extraction site will be
      completely relieved.

      Stage I Dental Implant Surgery Surgical placement of a dental implant will be performed at 6
      months after tooth extraction. Radiographs, including a periapical of the study site, will be
      taken before the surgery. Following local anaesthesia and elevation of a full-thickness
      mucoperiosteal flap, the site will be clinically observed for any signs of inflammation,
      infection and presence of fibrous or bone tissue ingrowth. The same customised acrylic stent
      used for the case at the time of the tooth extraction will be used for measuring new ridge
      height dimensions in a manner similar to that described previously. Readings will be recorded
      as RHmeb2, RHmib2 and RHdb2. Ridge width will be measured as previously described and
      recorded as RW2.

      The patient in either the test or control group will be taken out of the study at this stage
      if it is found that the extraction site has undergone extensive bone resorption such as to
      warrant simultaneous bone grafting with implant placement or pre-implant bone grafting with
      delayed implant placement.

      Prior to implant placement, a core of bone of 2 mm diameter and 6 mm length at the healed
      extraction site will be obtained using a trephine bur (3i Implant Innovations Inc.; USA). The
      core of bone will be fixed and stored in 10% neutral buffered formalin and sent for
      microcomputed tomography (micro CT) scanning and histological preparation.

      The implant site will be prepared using successive drills, according to the Straumann®
      (Institut Straumann AG, Basel, Switzerland) dental implant surgical protocol. A dental
      implant (Straumann® Bone Level) of the appropriate length and diameter will then be inserted
      at an insertion torque of between 20 Ncm and 40 Ncm. After placement of the dental implant,
      Implant Stability Quotient (ISQ) will be measured by Resonance Frequency Analysis (RFA) using
      the Osstell® machine. A cover screw will be placed over the implant. A releasing incision of
      the periosteum will be done if necessary and the surgical wound will be closed primarily with
      4/0 Vicryl®.

      A 5-day course of Amoxicillin (or Clindamycin if the patient was allergic to Penicillin) will
      be prescribed postoperatively, together with an analgesic and chlorhexidine digluconate 0.2%
      mouthrinse. The sutures will be removed 1 week postoperatively. The surgical site will be
      examined clinically for any signs of infection or wound dehiscence. The denture overlying the
      extraction site will be completely relieved.

      Stage II Dental Implant Surgery This will be performed 3 months after Stage I dental implant
      surgery. The site will be observed for any signs of inflammation, infection as well as
      clinical stability of the dental implant. ISQ will be measured by RFA using the Osstell®
      machine before attachment of the healing abutment.

      Analyses

        1. Clinical Analysis of Bone Resorption

           The amount of vertical bone resorption in millimeters (mm) at 3 aspects will be
           calculated:

           Mesio-buccal: RHmeb2 - RHmeb1 Mid-buccal: RHmib2 - RHmib1 Disto-buccal: RHdb2 - RHdb1

           The amount of horizontal bone resorption in millimeters at the mid-buccal aspect will be
           calculated:

           RW1 - RW2

        2. ISQ ISQ at Stage I and II dental implant surgery will be measured by 2 independent
           parties using RFA for both the test and control groups.

        3. Radiopacity Grading Scale The degree of radiopacity of the tooth socket observed on the
           periapical radiograph taken at 6 months post-extraction in both the test and control
           groups will be graded according to the following scale.

      1 = radiolucent similar to tooth socket* 2 = increased radiopacity but less than surrounding
      bone 3 = increased radiopacity similar to surrounding bone 4 = increased radiopacity more
      than surrounding bone

      * compared with baseline periapical taken of tooth socket immediately after surgical
      extraction

      The investigator performing the grading will be blinded to the grouping of the radiographs.

      4) Micro CT Analysis

      Quantitative analysis of bone regeneration in the test and control specimens will be
      performed using micro CT (SkyScan 1076, Kontich, Belgium). The specimens, consisting of 2 mm
      diameter by 6 mm length core of bone, will be placed in a sample holder and scanned through
      180° at a spatial resolution of 30μm. The image data from the scanned planes will be
      subsequently thresholded, reconstructed to create 3D images and analysed using VGStudio Max
      1.1 and CT Analyzer software (Volume Graphics GmbH, Heidelberg, Germany). The region of
      interest (ROI) will be defined by the boundaries of the specimen of each slice. The ROI will
      be interpolated through the entire length of the specimen to form the volume of interest
      (VOI). To select the area for bone, a bone-defining threshold will be set manually and kept
      constant for all the images. The percentage bone volume (BV%) will be obtained from the ratio
      of bone volume (BV) to total volume (TV):

      BV% = BV/ TV

      5) Histological Analysis After micro CT scanning, the specimens will be dehydrated in a
      graded series of ethanol, embedded in glycol methacrylate resin and polymerised. The block
      will be trimmed to remove excess plastic with an industrial vertical band saw and cut along
      its long axis with a diamond band saw (EXAKT standard saw). Ground polished sections of 10 μm
      thickness will be made using the EXAKT micro grinder system (EXAKT Technologies, Inc.,
      Oklahoma City, OK) and will be subsequently stained with Hematoxylin and Eosin (H&E),
      Goldner's trichrome and von Kossa for descriptive histology.

      (iii) Methods for protecting against other sources of bias (eg. blinding or masking. If
      blinding is not possible, please explain why and give details of alternative methods proposed
      or implications for interpretation of trials results)

      As this study will compare the use of a device in a tooth socket (test group) versus no
      device (control group), blinding is not possible. To reduce bias, 2 independent parties will
      perform the ridge dimension and ISQ measurements.

      The investigator performing the Radiopacity Grading Scale will be blinded to the grouping of
      the radiographs. Blinding for the micro CT and histology analyses is not possible as the
      presence/ absence of PCL-TCP scaffold will be obvious in the specimens.
    

Intervention name(s): PCL-TCP scaffold; Geistlich Bio-Gide collagen membrane
Intervention type(s): Device; Device
Intervention description(s): During the surgery, the scaffold will be shaped by cutting and shaving with a scalpel so as to fit the extraction socket snugly at the crestal half to two-thirds aspect. A collagen membrane will be placed over the scaffold at the crestal aspect of the socket. The periosteum of the buccal flap will then be incised to allow a tension-free primary closure with 4/0 Vicryl® suture.; A collagen membrane will be placed over the crestal aspect of the socket and the periosteum of the buccal flap will be incised to allow a tension-free primary closure with 4/0 Vicryl® suture.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: 3D Printed Scaffold Device