DLP Versus SLM Stackable Surgical Guide
Condition: Accuracy of Stackable Guide
Study type: Interventional

Summary: 
      Purpose; The purpose of this research is to make a comparative estimation for the positional
      accuracy of dental implants inserted by selective laser melting and digital light processed
      computerized stackable surgical guides for patients with maxillary terminal dentitions.

      Materials and methods; Twenty-four dental implants will be installed in partially edentulous
      patients who will be applied for treatment of tooth loss and required fixed prosthodontic
      rehabilitation. Virtually designed prosthetically driven fixation base with its stackable
      surgical osteotomy guide will be used for bone reduction after tooth extraction and osteotomy
      preparation respectively. The inserted implants will be divided equally into two groups
      according to stackable surgical osteotomy guide to either selective laser melting (SLM) CO-Cr
      metal or digital light processing (DLP) surgical-guides. The final actual implant position
      will be compared to the preoperative planned position and the deviations will be calculated
      for coronal deviation, apical deviation in mm, and two angular deviation measurements in
      degrees.
    

Detailed description: 
      Preoperative evaluation:

      intra-oral and extra-oral examination and medical history for each patient will be recorded
      to assure that the patient will be eligible for the research.

      Written informed consent will be assigned by the patients who will be included in the study.

      Preoperative records Polyvinyl siloxane (PVS) impressions for both arches will be made. Also,
      an interocclusal record will be recorded.

      The poured upper and lower cast will be mounted on the articulator and will be scanned using
      a tabletop scanner (DOF swing, DOF, Korea). the scanned file will be saved in stl format
      Clinical digital photographs for digital smile design will be used to generate a smile design
      driven by an individual's face and smile display. As such, it is critical to have at least
      two portraits representing the lips at rest and another one for a broad smile For each
      patient, a preoperative cone beam computed tomography (CBCT) scan with the two jaws separated
      via cotton rolls to separate the volume of interest using a CBCT machine (Scanora 3Dx,
      Soredex- Finland ) will be taken and saved as Digital Imaging and Communication in Medicine
      (DICOM) files. The saved STL files will be imported into computer-aided design (CAD) software
      ( Implastation, prodigident, USA) and superimpose these files to the DICOM files and the JPEG
      photo files.

      Implant and prosthesis planning Virtual tooth setup of the desired prosthetic outcome can be
      designed to achieve true, restoratively driven implant placement when applied to 3-D surface
      DICOM data. Performing this virtual wax-up will be done by selecting and importing maxillary
      teeth from the software library, followed by adjustment of each tooth shape and position
      according to the patient's occlusion, gender, and smile. The final plan often requires bone
      reduction to facilitate implant placement and the necessary restorative space for the
      prosthesis.

      A 3-dimensional implant planning using a Software Planning program (Implastation,
      ProDigident, USA), allows the clinicians to evaluate the osseous tissues concerning the ideal
      prosthetic position of the virtual waxed-up maxillary teeth. From this information, the sizes
      and implant receptor sites will be digitally evaluated in all of the necessary views,
      including cross-sectional, coronal, sagittal, and axial sections followed by virtual
      placement of the implants.

      The stackable guide that will be planned to transfer the virtual plan to the operating field
      intraorally and consists of 3 components:

        1. carrier guide: it takes its support from the remaining dentition and has a foundation
           base attached to it by locks. its function is to transfer the foundation base to its
           accurate place in the patient mouth.

        2. foundation base: fixed to bone along the whole surgery time by fixation pins and has
           locks to be attached with subsequent osteotomy guides.

        3. osteotomy guide: contains the hole through which the implant drilling will be guided.

      The outline of the surgical guide will be determined. and then the thickness and path of
      insertion. the amount of bone to be reduced will be determined .. a tooth-supported carrier
      (pin guide) will be designed, it takes its support from the remaining dentition. height of
      the foundation guide and locations of widely separated 4 anchor pins will be planned so that
      anchor pins help in achieving the highest degree of surgical accuracy, and then a
      tooth-supported carrier (pin guide) will be designed, it takes its support from the remaining
      dentition and accurately replicates the position of the anchor pins for subsequent guides,
      hence ensuring an accurate replication of the guide position.

      With this protocol, teeth removal and bone reduction will be done virtually to provide the
      available restorative space (from the crest of the bone to the proposed incisal edge position
      and posterior occlusal plane).

      Sleeveless osteotomy guide holes and offset will be designed corresponding to the guided
      drill kit that will be used(OGS guided kit, oxy implant, Italy) Finally, all guides will be
      exported as standard triangle language (STL) files and sent to additively manufactured
      machines.

      Grouping:

      The inserted implants will be divided equally into two groups according to the stackable
      surgical osteotomy guide fabrication/printing technique:

      First group; in which implants will be placed using selective laser melting (SLM) CO-Cr metal
      surgical-guides Second group; in which implants will be placed using digital light processing
      (DLP) resin surgical-guides

      Surgical stents fabrication:

      For Digital light processing (DLP): DLP printers have a digital projector screen used to
      flash a single image of each layer on the entire platform at once using curable photopolymer
      resin. A vat of liquid photopolymer will be exposed to UV light from a digital projector
      under safelight conditions. The printer (Photon, Anycubic, China) builds the stent one layer
      at a time by tracing a laser beam on the surface of a vat of printable Resin liquid (SG
      resin, pro shape, turkey). The process will be repeated, forming another layer on top of the
      previous layer. This process continues layer by layer until the stent is completed. Printing
      will be started with a build angle of 45 and the printing thickness on the z-axis was set at
      100 microns. After printing, the supports will be removed and the printed stents will be
      cleaned in an ultrasonic bath with ethyl alcohol for 2 minutes to remove excess resin. Stents
      will be post-polymerized for 30 minutes using an ultraviolet polymerization unit (bre. Lux
      power Unit 2, Bredent, Germany).

      Regarding Selective Laser Melting (SLM); the STL file will be segmented into cross-sectional
      layer representations and then exported to a metal laser melting machine (vm120, Vulcan tech,
      Germany). To fabricate the prototype, this automated printing machine received numerical
      inputs of the surgical stent design. Sintering of the powder alloy (Starbond easy Pulver 30,
      Scheftner dental, Germany) to the predesigned guide via high-energy laser beams that traced
      across a powder bed of densely compacted powdered material, resulting in local melting and
      fusing of the particles. According to the 3D data fed into the machine, metallic powders will
      melt together, in a layer-by-layer strategy, creating three-dimensional objects.

      Laser spot diameter of 0.08-0.1 mm, sintering speed of 1100-1200 mm/s, a layer thickness of
      0.02 mm, and printing angle of 45 degrees, will be considered the parameters of the laser
      melting machine that will be used for the SLM stent fabrication. SLM stents will be extracted
      from the base plate and homogenization treatment will be performed at 1150ᵒ C for 30 minutes.

      Surgical phase All surgeries will be performed by the same operator under complete aseptic
      conditions. The patients will be locally anesthetized.

      Utilizing the existing dentition to position carrier resin guide to which everything else
      will be related. Verification of the carrier guide of the pin guide over the teeth will be
      done.

      After verification, the carrier will be securely locked to the foundation metal printed guide
      and delivered over the teeth. This method allows for the metal foundation guide to be
      correctly positioned. Four anchor pins will be utilized to stabilize the metal foundation
      guide (divided equally into anterior and posterior regions bilaterally). An anchoring twist
      drill will be used with copious irrigation for the preparation of the fixation screw pathway.
      After that, four anchoring screws will be driven in the anterior and posterior areas After
      the FG will be secured to the bone, the pin guide will be removed, leaving the maxillary
      teeth available for extraction. The teeth will be all carefully removed, leaving the
      remaining alveolus exposed. The outer aspect of the metal FG will be used to determine the
      amount of bone reduction. Once the alveoloplasty will be completed after the elevation of the
      palatal flap, a third surgical template which is the stackable osteotomy surgical stent will
      be positioned and mechanically locked to the top of the FG for guided implant placement.

      The osteotomy sites will be prepared, through the planned locations and angulations of the
      surgical guides, using a sequential series of drills of the OGS Surgical Kit After the last
      drill, six (NeoBiotech Co., Seoul, Korea) implants will be placed freehand after using drill
      guides, and tightened manually to 35N/cm. Finally, cover screws will be tightened (10 N/cm)
      to the implants and the surgical guides were removed. The patients will be instructed to
      complete the course of antibiotic and anti-inflammatory for 5 days after surgery, to maintain
      good oral hygiene.

      Evaluation After the surgery, patients will be submitted to a CBCT scan using the same
      parameter as the preoperative scan. And the data of the postoperative scan will be
      superimposed over the preoperative plan to assess the accuracy of the implant placement using
      the software (blueskybio 4, BlueSky bio, USA). The final actual implant position will be
      compared to the preoperatively planned position and the deviations will be calculated for
      global angel deviation and global linear coronal and apical deviation in mm.
    

Intervention name(s): stackable guide
Intervention type(s): Device
Intervention description(s): different types of stackable guide
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Other
Keywords: implant; stackable guide; 3d printing