After tooth extraction, bone loss can compromise future dental implant treatment. Dentists often use biomaterials to preserve bone, but in many cases these materials are left exposed to the oral environment, where saliva and bacteria may affect healing. This study will investigate how different collagen-based biomaterials behave when exposed in the mouth, evaluating healing, bone changes, bacterial contamination, and patient experience. Sixty patients will be included in a randomized clinical trial comparing two commonly used biomaterials and natural healing. The results will help clinicians choose safer and more effective treatments, improving outcomes for patients undergoing tooth extraction and future implant rehabilitation.

1. Ethical considerations and patient selection This study will be previously submitted to the ethical committee of PUCRS - Brazil for appreciation and evaluation following the international ethical guidelines for clinical studies. Following ethical acceptance, patients needing non-molar tooth extraction with four/three walls of alveolar integrity will be selected for this study. Exclusion and inclusion criteria will be applied in the patient's selection according to potential systemic diseases and external habits that influence bone regeneration. (please, check inclusion and exclusion criteria).

2. Surgical procedures and group division Following patient selection, minimal invasive extractions will be performed and standard alveolar preservation will be done using Bio-oss Collagen® - Geistlich for alveolar filling and (BioGide® or Mucograft® Seal - Geistlich, depending on the study group) for covering the gap-filling procedure showing one biomaterial side exposed to the oral cavity environment. The patients will be divided randomly into three experimental groups of 20 patients each, completing 60 patients. One group will receive alveolar preservation with Bio-oss Collagen® + BioGide® and the other group will receive alveolar preservation with Bio-oss Collagen® + Mucograft® Seal. A negative control group will be applied without any type of alveolar preservation, only minimally invasive extraction.

   Evaluation time points will be named T0, T1, T2, T3 (T0 = immediate after surgery, T1 = 1 week, T2 = 3 weeks, T3 = 3 months).

   After surgeries, patients will receive detailed verbal and written post-operative instructions, prescriptions for anti-inflammatory medication (ibuprofen 600 mg for 3 days, if needed), and antibiotic therapy (amoxicillin 500 mg every 8h for 7 days or, in case of penicillin allergy, clindamycin 300 mg every 6h for 7 days). Patients will be recalled at 1 (T1), 3 weeks (T2), and after three months (T3). Sutures were removed at 1 week. Patients will be advised to not use mouth rinses in order to not compromise the surgical procedure. Normal hygiene using toothbrushes and toothpastes will be indicated to the patients to maintain clean conditions.

   Following surgical procedures, the surgical sites will be evaluated regarding biomaterial contamination, clinical tissue healing, and radiographic conditions.

3. Biomaterial surface contamination For biomaterial contamination, a sterilized swab for bacterial analysis will be used directly over the procedure (per patient/per time) for investigation of potential biomaterial surface contamination at T0, T1, and T2. Following this, the bacterial collection will be processed and evaluated at the Microbiological laboratory. The potential bacterial collection will be spread in agar plates and cultured in a stove under appropriate bacteria conditions for 24 hours. Bacteria colonies will be evaluated and counted comparing the proposed groups and time points in this study.

   A control collection will be performed before the surgical procedure in the tooth extraction region using a sterilized swab to evaluate the previous microbiome and similarities to the post-surgery evaluations.

4. Radiographic evaluation For radiographic investigation, digital periapical radiographs will be performed on pre-operatory days (for diagnostics of tooth extraction); at T1 and T3, evaluating potential procedure failures or infiltration by comparing the time points. Measurements will be performed digitally using the radiographic software associated with the X-ray to investigate regenerated bone and possible bacterial infiltration comparing the groups.

5. Qualitative and quantitative clinical outcomes Early clinical healing will be evaluated at three different times (T0, T1, T2, T3) through clinical observation and alveolar measurements using a periodontal probe in millimeters. Linear alveolar size and soft tissue contour measurements will be evaluated using a periodontal probe (measuring the mesio-distal and buccal-lingual/palatal distance in millimeters) according to the alveolo size and possible alveolo changes, directly after tooth extraction, at T0, T1, T2, and T3. Additionally, qualitative photographs will be performed for evaluation of early tissue healing, possible infection, possible failures, and/or dehiscence.

6. Patient-reported outcome measures Patients will be asked to rate their level of post-operative discomfort and overall satisfaction after alveolar ridge preservation at T0, T1, T2 and T3. The questionnaire will be applied using a simple table with a 100-point visual analogue scale where the patient will be able to select from 0 to 100 (0 for worst evaluation and 100 for the higher evaluation). (Couso-Queiruga et al. Influence of healing time on the outcomes of alveolar ridge preservation using a collagenated bovine bone xenograft: a randomized clinical trial. Journal of clinical periodontology, 50(2), 132-146, 2023).

7. Statistical analysis The data will be analyzed using one-way ANOVA, followed by post hoc testing Tukey HSD test if necessary, comparing the three experimental groups in the three different time points. Bacterial assays will be performed in triplicate for each time point. A significant variation between groups was considered to occur at 5% (p < 0.05).

Inclusion Criteria:

• Adult subjects in need of non-molar maxillary or mandibular single tooth extraction at the PUCRS university - Porto Alegre - Brazil.

  1. > 18 years of age
  2. non-molar tooth indicated for extraction
  3. intact sockets upon extractions
  4. Patients using removable provisional prosthesis (accessible to remove possible contact with surgical site) or patients without prosthesis after tooth extraction.

Exclusion Criteria:

1. Current smokers
2. Uncontrolled Diabetes Mellitus
3. Mandibular incisors
4. Patients receiving chemo or radiotherapy or history of these treatments in the previous 5 years
5. Any other disease or medications that may compromise normal wound healing
6. Unwilling or unable to sing the informed consent