The primary aim of this study is to evaluate 1-year survival of maxillary molars with subclass C vertical furcation involvement after vital root resective therapy

Schedule of Treatment for each visit:

Visit 1 - Baseline (day 0)

• Informed Consent, medical/dental history and demographics
• Record concomitant medications
• Periodontal assessment with recording of full mouth PPD, gingival recession, bleeding on probing (BOP), tooth mobility and furcation involvement
• Long cone periapical radiographs with paralleling technique (if radiograph taken in previous 3 months is not available)
• CBCT examination
• Photographs
• Oral hygiene instructions
• Sensitivity tests

Visit 2 - Treatment (intervention) visit

• Medical/dental history update and record adverse events and/or concomitant medications
• Root-resective surgery
• Post-treatment regime will be outlined according to protocol

Visit 3 - 1 Week Post-Intervention and Further Treatment

• Update medical/dental history and record adverse events and/or concomitant medications
• Clinical photos
• Post-treatment regime will be outlined according to protocol

Visit 4 - 1-Month Post-Intervention

• Update medical/dental history and record adverse events and/or concomitant medications
• Full mouth plaque score (FMPS) recording (6 sites per tooth)
• Oral hygiene reinforcement, full mouth supra-gingival debridement to remove new accumulations of plaque or calcified deposits and supra-gingival polishing
• Clinical photos
• Sensitivity tests

Visit 5 - 3 Months Post-Intervention

• Update medical/dental history and record adverse events and/or concomitant medications
• FMPS recording
• Oral hygiene reinforcement, full mouth supra-gingival debridement to remove new accumulations of plaque or calcified deposits and supra-gingival polishing
• Periodontal assessment consisting of recording of full mouth (6 sites per tooth) PPD, recession, BOP, mobility (tooth level) and furcation involvement (for each multirooted tooth)
• Clinical photos
• Sensitivity tests

Visit 6 - 6 Months Post Intervention

• Update medical/dental history and record adverse events and/or concomitant medications
• Clinical photos
• FMPS recording
• Periodontal assessment consisting of recording of full mouth PPD, recession, BOP, tooth mobility and furcation involvement
• Oral hygiene reinforcement, full mouth supra- and sub-gingival debridement to remove new accumulations of plaque or calcified deposits and supra-gingival polishing
• Sensitivity tests

Visit 7 - 9 Months Post Intervention

• Update medical/dental history and record adverse events and/or concomitant medications
• Clinical photos
• FMPS recording
• Periodontal assessment consisting of recording of full mouth PPD, recession, BOP, tooth mobility and furcation involvement
• Oral hygiene reinforcement, full mouth supra- and sub-gingival debridement to remove new accumulations of plaque or calcified deposits and supra-gingival polishing
• Sensitivity tests

Visit 8 - 12 Months Post Intervention

• Update medical/dental history and record adverse events and/or concomitant medications
• Clinical photos
• FMPS recording
• Periodontal assessment consisting of recording of full mouth PPD, recession, BOP, tooth mobility and furcation involvement
• Oral hygiene reinforcement, full mouth supra- and sub-gingival debridement to remove new accumulations of plaque or calcified deposits and supra-gingival polishing
• Sensitivity tests

Description of study procedures:

Clinical periodontal examination:

Dichotomous (no/yes) full mouth plaque scores (FMPS) will be recorded, identifying tooth surfaces revealing the visual presence of plaque following the use of plaque-disclosing tablets. Periodontal measurements will be taken by the calibrated examiner at six sites per tooth using a manual University of North Carolina (UNC-15) periodontal probe. The following periodontal measurements will be taken full mouth at 6 sites per tooth: probing pocket depth (PPD), recession of the gingival margin from the cemento-enamel junction (CEJ), dichotomous (no/yes) bleeding on probing (BoP). Recession will be recorded as a negative number if the gingival margin is above CEJ; and as a positive number (incl. 0) if margin is on (0) or below CEJ (>0). Further, tooth mobility (no/yes and degree 1, 2 or 3), horizontal furcation involvement using a Nabers probe (no/yes and degree 1, 2 or 3) and finally vertical furcation involvement (no/yes and class A, B or C) measured with a UNC-15 probe will be recorded. Clinical attachment levels (CAL) will be calculated as PPD + recession. This is part of standard care.

Sensitivity testing:

Cold stimulus (Endo-Frost; Roeko GmbH & Co - Coltène-Whaledent, Switzerland) will be applied on a sprayed cotton pellet to the cervical third of the buccal and palatal surfaces of isolated teeth after gentle air-drying and for up to 10 seconds per tooth. A negative response will be recorded when the subject fails to indicate a response on two consecutive occasions on each surface.

Electric testing will be carried out following manufacturer instructions by placing the toothpaste-impregnated probe tip to the occlusal third of the tooth. A plastic interproximal matrix band will be used between teeth to prevent current conduction to the adjacent teeth. A negative response will be recorded when the tester reaches its maximum level on two consecutive occasions.

Root-resective surgery:

Following rinsing with chlorhexidine digluconate 0.12% mouthwash (Perio-Aid; Dentaid, Spain) and administration of local anaesthetic (Xilonibsa 20 mg/ml + 0,0125 mg/ml; Inibsa SA), intrasulcular and/or submarginal incisions will be performed as judged by the clinician. Releasing incisions may be performed if necessary. Full-thickness flaps will be elevated to access the furcation area. Granulation tissue will be eliminated with the aid of curettes (Hu-Friedy Manufacturing Co LLC), and root surface debridement will be performed with ultrasonic devices (EMS, Switzerland) with specific thin and delicate inserts and/or curettes. The root scheduled for resection will be separated from the root using high-speed rotary instruments. Once complete root separation is verified, it will be carefully elevated from the socket. Additional cuts in the separated root may be performed as necessary in order to minimise trauma to the socket and the tooth. Following root resection, the tooth will be isolated with rubber dam and a light-cured resin barrier (Opaldam, Ultradent Products) to avoid contamination of the pulpal wound. A 3-mm amputation of the pulp will be carried out with sterile round diamond burs under water cooling, to allow space for both pulp capping and restorative material. Pressure will be applied on the exposed pulp for up to 5 minutes with a sterile cotton pellet soaked in 2.5% NaOCl to achieve hemostasis. The exposure cavity will be filled with Biodentine (Septodont, Saint Maur des Fossés, France) following manufacturer's instructions on material manipulation and placement. After initial setting of the capping material (12 minutes from mixing), a rubber dam will be placed in order to isolate the resection site and avoid moisture, and 1 mm of Biodentine will be removed with a sterile tungsten carbide bur at low speed (5000-10000 rpm) under copious irrigation. A self-etching dentine adhesive (Clearfil SE Bond; Kuraray, Osaka, Japan) will be applied to the cavity and subsequently restored with a light-cured resin composite (Clearfil AP-X; Kuraray, Osaka Japan). Finishing and polishing of the restoration will be accomplished with a very fine diamond bur. Careful recontouring of the resection area will be performed in order to avoid ledges or plaque-retentive anatomy. Bone resection will be performed with rotary and manual instruments as judged by the clinician. Flaps will be will be repositioned and sutured with 5/0 and 6/0 monofilament sutures (Seralene; Serag-Wiessner GmbH & Co. KG). Gentle pressure will be applied with a moist gauze until haemostasis is achieved.

Follow-up Procedures:

All sites in the mouth of participants will receive the required periodontal treatment by a trained therapist (periodontist/dentist/hygienist) throughout the duration of the study, as judged by the examining clinician. This is likely to involve supportive periodontal therapy (including supra- and sub-gingival debridement, polishing, oral hygiene re-enforcements and motivation) but may also involve more advanced periodontal treatment including surgical options. If any participant-related acute medical or dental problems arise, these will be managed in the appropriate manner in line with routine clinical practice. Where appropriate, if care is required in relation to one of the study treatment procedures, participants will be seen at the study site. In other cases, following an assessment of the most appropriate treatment required, participants will be appropriately directed to their medical or dental general practitioner.

At the study completion phase the patient may be further allocated for treatment if it is deemed necessary. If no such treatment is required then the patient will be enrolled in a supportive periodontal therapy program.

'Rescue' therapy: In case of continued CAL >2mm at 2 consecutive appointments, an extra session of sub-gingival debridement under local anaesthesia or an access flap operation will be planned for the study site, as judged by the examining clinician. In case of development of endodontic pathology: consider endodontic therapy (if indicated) or otherwise extraction (if combined with mobility > I). In the case of a development of root fracture or in cases of excessive mobility or patient discomfort, extraction will be considered and discussed with the patient. Any further treatment carried out on the molar with FI will be recorded and analysed. If any extraction is carried out, the reason for extraction will be documented in the case-report forms.

In case endodontic pathology developed, the patient will be provided endodontic treatment.

Radiographic Assessments:

The selected study defect will be detected based on radiographs often taken at the new patient consultation or provided by referring dentists. A long-cone periapical radiograph of selected study sites will be taken by one of the study investigators at baseline, 6 and 12-month follow-up visits. Additional radiographs may be taken when considered clinically necessary by the treating clinician.

These radiographs are considered standard of care as they will be important for treatment planning purposes and for assessing the treatment response. They will also help decide whether or not the teeth are still maintainable post-treatment.

A preoperative limited-volume CBCT will be taken in order to assess root morphology and presence of periapical pathology. A follow-up CBCT scan will be taken at 12 months in order to assess the presence of periapical pathology and intra-pulpal calcifications in reaction to the treatment.

Inclusion Criteria

• Minimum of 12 teeth present
• Diagnosis of Severe Periodontitis stage III or IV (Tonetti et al., 2018)
• At least one maxillary molar with: i) degree II-III horizontal furcation involvement (Eickholz and Walter, 2018), ii) class C vertical furcation involvement (bone loss up to the apical third of root cones) (Tarnow and Fletcher, 1984, Tonetti et al., 2017), iii) residual probing pocket depths > 5 mm, iv) maximum mobility degree I (Hamp et al., 1975) and v) not already accessible for self-performed oral hygiene
• Received a course of non-surgical periodontal therapy within the past six months
• Positive response to electric and cold testing

Exclusion Criteria

Patient:

• Full mouth plaque score > 30%
• A course of antibiotics within the past 3 months
• Pregnant/lactating women
• Relevant medical history as evaluated by the examining clinician which may have the potential to affect periodontal surgical treatment (such as disease affecting clotting ability)
• Individuals on long-standing (2 or above years) supportive periodontal therapy (SPT) management plans

Molar affected by FI:

• Ongoing endodontic pathology affecting the furcation-involved molar, as judged by the examining clinician
• Teeth associated with signs or symptoms indicative of pulpal or periapical pathology
• Evidence of coronal cracks upon root resection
• Previous periodontal surgical treatment to the furcation-affected molar within the previous 5 years
• Endodontically treated tooth
• Restorations affecting more than 2 walls or 1 cusp
• Molar tooth acting as a bridge abutment
• Planned for extraction (for strategic/restorative reasons)
• Root trunk exceeding ½ of the total root length
• Fused roots
• Remaining furcation not accessible for self-performed oral hygiene
• The presence of occlusal dysfunction as assessed by the examining clinician
• Sinus floor anatomy limiting possible osseous resective surgery
• Tooth mobility causing discomfort to the patient