## 2 The First and Second Parts of Making the Surgical Guide for TADs
### Part 1: Rationale for Using a Surgical Guide in the Implantation of TADs
#### 2.1.1 Collecting Data, Planning, and Designing in Consideration of the Making of the Surgical Guide  
The sites for, number, and types of TADs are influenced by the nature of the malocclusion and the treatment plan. However, the placement and design must consider the availability of quality and quantity of the bone at the proposed anatomical site. These are assessed with volumetric data of CBCT and other X-rays. Therefore, more than a panoramic X-ray or other 2-dimensional data is required [36]. The Hounsfield value at the site should be evaluated to determine bone density. For spongy bone, the value should be around 300 HU, while cortical bone should be above 500 HU. For optimal results, it is recommended that the thickness of the cortical bone should be at least 0.5 mm [37; 38]. If the values are lower than these standards, it is best to check the surrounding sites. If the density is still unsuitable for TAD placement, another site for TAD placement should be explored until the minimum requirements are met. Making a secure placement site will reduce failure risk and prevent reimplantation. The digital dental impression data obtained from the intraoral scan in SLT format and DICOM data of CBCT are shared with the professional outsourced laboratory or in-house laboratory for processing. The success and failure of TADs can range from issues with the mucosa and the bone condition, mainly density and the thickness of the cortical bone, to the TAD design itself [35]. The design of the surgical guide is created in the application software. Initially, designing can be performed by the dental technician and then checked by the doctor; therefore, communication is the key to success. Orthodontists should check the manoeuvrability to position the TAD toward the desired insertion location and preferred angulation. The final design by the doctor is crucial because only the doctor knows the patient's situation, such as how far the patient can open their mouth and the instruments required, keeping anatomical limitations in mind, especially the placement of the posterior region. Once the planning and design are completed, the laboratory will do the 3D printing of the pilot drill and the guide of the specific screw. Each placement might have a different pre-drilling and TAD size; therefore, the technician should fully know about the intended TADs, their design, and size. Two guides are advised to be fabricated for accurate implantation. A vertical direction of placement on a flat surface of bone can be performed easily with self-drilling TADs; however, when it comes to an angulated surface, it can be slippery to make a hole directly on the surface of the cortical bone. As explained in the last reference, several failure attempts could tear off the mucosa and affect the healing process. Therefore, two surgical guides are needed; one is for the pre-drilling to make the initial hole, and the other is for the TAD. After the 3D printing, the technician will wash and cure these to finish the laboratory procedure. The surgical guides are then sent to the orthodontist's office. The need to place the TAD for anchorage depends on the demand for specific treatment biomechanics. Generally, it is wise to avoid interdental space placement whenever possible and choose places without a tooth or away from the tooth. The point of selection is relatively easy on the maxillary but has fewer anatomical choices available in the mandible. 1. In the maxilla, CBCT is used to look for the ideal places and the palatal sites in the T-zone, as described by [PERSON] [39]. The system's benefit is two screws being used to connect a plate to make it a sturdy anchorage for 3D movement of the upper teeth. Therefore, the two screws' placement is critical to insert the plate easily and quickly, such as parallel or close to the parallel to provide easy fixation [40; 41; 42; 43]. The surgical guide will facilitate the parallel insertion of TADs. TADs are placed at the best bone density in the area intended to be the anchorage placement.