Evaluation of Bone Quality and Primary and Secondary Stability of Implants Installed in Alveolar Regeneration Area by Three Different Techniques

The objective of this randomized controlled clinical study was to compare bone quality between three different alveolar ridge preservation methods, also with the evaluation of primary and secondary dental implant stabilities at these sites.

In the present study will be collected 24 patients, with indication of extraction of premolars or upper incisors. All participants will sign a Free and Informed Consent Form (TCLE), agreeing to participate voluntarily in this research.

Patients were randomly allocated into three groups according to the following treatments:

Group RET: Closure of the alveolus by first intention through palatal flap sliding according to the technique of Khoury.

SBC Group: Fill bone alveolus with Bone Ceramic® graft (Straumann AG, Basel, Switzerland) and cover it with palatal flap according to the technique of Khoury.

PRO Group: Alveolus sealing by a temporary ovoid pony of acrylic resin.

All patients will be prescribed the use of amoxicillin 2G, dexamethasone 4 mg and dipyrone sodium 500 mg one hour before the surgical procedure. After intra- and extraoral antisepsis with 0.12% and 2% chlorhexidine respectively, the sterile surgical fields were placed. Local anesthesia was obtained with lidocaine 2% epinephrine 1: 100,000.

With the aid of a surgical guide will be collected material for histological analysis, removed using trephine drill with 2.0 mm diameter. Samples will be removed before the incision, to be defined through the presence of gingival tissue the most coronal part of the sample. They will be placed immersed in a container with 10% formalin solution.

Then a linear incision will be made on the alveolar ridge in the region and detachment of the flap. The implants and components to be used are from Neodent® (Curitiba, PR, Brazil). The diameters used were standardized in 3.5 x 11.5 mm or 3.5 x 8 mm, depending on the remaining height of the collar. The milling and insertion system of the implants will follow the protocol recommended by the manufacturer. The drill rotation of the drills does not exceed 800 rpm, as recommended for Type III and IV bones.

The initial insertion of the implant will occur with the use of the contra-angle regulated at 30 rpm, the final insertion of the implant will be performed using a manual torque wrench, to measure the insertion torque and the registered value, preferably not exceeding 60 N.cm.The prosthetic component should be installed immediately after installation with an implant with a maximum torque of 20 N and on it adapted the SmartPeg® (Integration Diagnostics AB, Göteborg, Sweden). According to the manufacturer, the device generates a series of signals with different frequencies in Hertz (Hz) and these values are immediately converted to ISQ (Implantation Stability Coefficient), providing fast and accurate monitoring. The ISQ linear scale ranges from 1 to 100, with high ISQ values assuming high quality bone implant anchors. The calibration will be performed on the buccal and palatal surfaces of the intermediaries, that is, each implant submitted to 2 readings. The readings will be captured and recorded for further analysis.

Patients who do not achieve a minimum insertion torque of 30 N will have the micro-abutments removed, the implant cover screw installed, and sutured. In these patients, they will not have the values of SSI in the period of osseointegration of the implants. Implants that presented insertion torque equal to or greater than 30 N were to be maintained with the prosthetic components in position to have the repeated evaluations at intervals of 7 to 10 days, 30 days and 60 days, for evaluation of SSI in the period of osseointegration. With the objective of not subjecting the implant to torque and torque during this period and to avoid interfering with the osseointegration process, the micro-piers will be covered with the micro-pillar protection screws with digital pressure only, and the incision will be sutured.

Patients will receive guidance regarding postoperative care. It will be prescribed amoxicillin 500mg every eight hours for seven days, nimesulide 100mg twelve in twelve hours for three days, dipyrone sodium 500mg in case of pain and mouthwashes with chlorhexidine 0.12% of twelve in twelve hours until the removal of the sutures.After the surgical procedure, periapical radiographs of the operated region will be performed to check the position of the implants.

The microCT examination of each bone sample will be performed by the Skyscan® micrograph 1272 (Skyscan, Antwerp, Belgium) to analyze the bone microarchitecture of each location from which the implants were installed. After the analysis the samples will be subimeted to immunohistochemical tests.

Eligibility Criteria:
Inclusion Criteria:

* Extraction of premolars
* Canines or incisors
* Having two adjacent teet
* Due to root fracture
* Extensive cavities that do not allow restorative treatment and / or unfavorable -endodontic prognosis
* Systemically healthy

Exclusion Criteria:

* Patients who use any drug that influences bone metabolism
* Patients with a history of head and neck radiotherapy
* Patients undergoing chemotherapy for the treatment of malignant tumors at the time of the study
* Patients with severely resorbed alveoli
* Smokers
* Pregnant