Comparison of Anesthetic Efficacy and Safety Between Inferior Alveolar Nerve Block and the Infiltrative Technique for the Treatment of Peri-implant Diseases in Posterior Mandibular Implants

This study is a triple-blind randomized clinical trial designed to compare the anesthetic efficacy and safety of two local anesthesia techniques used for the surgical treatment of peri-implantitis in posterior mandibular implants: the inferior alveolar nerve block (IANB) and the infiltrative technique (TINF), both performed with 4% articaine and epinephrine 1:100,000. Background and rationale Peri-implantitis is an inflammatory disease affecting the tissues surrounding osseointegrated dental implants. It is characterized by progressive peri-implant bone loss together with clinical signs of inflammation. It represents one of the most relevant biological complications in implant dentistry. Initial management of peri-implant diseases usually involves non-surgical therapy, including mechanical debridement of the implant surface, antiseptic irrigation, and, in selected cases, local or systemic antimicrobial therapy. However, when peri-implantitis progresses or does not respond adequately to non-surgical treatment, surgical intervention is often required. Surgical treatment may include flap elevation, removal of granulation tissue, implant surface decontamination, bone recontouring, regenerative procedures, soft tissue surgery, or combined approaches, depending on the morphology and severity of the defect. Adequate local anesthesia is essential to perform these procedures safely and predictably. This is particularly relevant in the posterior mandible, where dense cortical bone may limit the diffusion of local anesthetic solutions. Traditionally, the inferior alveolar nerve block has been the standard technique for achieving profound anesthesia in mandibular posterior procedures. Although generally effective, its success may be affected by anatomical variation, accessory innervation, technical difficulty, or incomplete nerve blockade. In addition, although uncommon, transient neurosensory complications have been described. The infiltrative technique has gained interest as a possible alternative, especially when using articaine, which has high tissue diffusion capacity due to its chemical structure. Articaine contains a thiophene ring, which increases lipid solubility and may facilitate penetration through dense tissues. It also has a rapid onset of action and favorable pharmacological characteristics for oral surgery. Despite this, the available evidence suggests that IANB may still provide greater anesthetic predictability in complex surgical procedures. There is a lack of well-designed randomized clinical trials directly comparing IANB and infiltrative anesthesia specifically in the surgical treatment of peri-implantitis in posterior mandibular implants. For this reason, the study aims to provide controlled clinical data that may help guide evidence-based anesthetic decision-making in this specific surgical context. Main objective The primary objective is to compare the anesthetic efficacy of the inferior alveolar nerve block and the infiltrative technique during the surgical treatment of peri-implantitis in posterior mandibular implants. Anesthetic efficacy will be assessed through the need for re-anesthesia during the surgical procedure. The absence of re-anesthesia will be considered evidence of successful anesthesia. Secondary objectives The secondary objectives are to compare both anesthetic techniques in terms of: Safety and incidence of adverse events. Intraoperative discomfort. Pain during anesthetic injection. Postoperative pain intensity. Duration of anesthesia. Patient satisfaction with the anesthetic technique and surgical experience. Need for rescue analgesic medication. Postoperative complications. Feasibility of the protocol for a future confirmatory clinical trial. Hypotheses The main null hypothesis is that the anesthetic efficacy of IANB, measured by the number or frequency of re-anesthesia events during surgery, is not superior to that of infiltrative anesthesia in the surgical treatment of peri-implantitis in posterior mandibular implants. The alternative hypothesis is that IANB provides superior anesthetic efficacy compared with infiltrative anesthesia in this clinical setting. Secondary hypotheses include the possibility that IANB may be associated with a different safety profile, lower intraoperative discomfort, reduced postoperative pain, and higher patient satisfaction compared with the infiltrative technique. Study design The study is designed as a randomized, triple-blind clinical trial. It is also described as a pilot and exploratory study because there is limited previous evidence in this exact clinical context, making it difficult to establish robust assumptions for a definitive sample size calculation. The trial will be conducted at the Dental Hospital of the University of Barcelona, specifically within the Master's program in Oral Surgery and Bucofacial Implantology. Study population The study will include consecutive adult patients attending the Implant Maintenance Unit or the Oral Surgery and Implantology service who require surgical treatment of peri-implantitis in posterior mandibular implants. Patients will be assigned either to the experimental group, receiving IANB, or to the control group, receiving infiltrative anesthesia. Inclusion criteria Participants must meet the following criteria: Age 18 years or older. Need for surgical treatment of peri-implantitis in the posterior mandibular region. Absence of relevant uncontrolled systemic disease, corresponding to ASA I or ASA II. Sufficient intellectual capacity to understand the study, provide informed consent, and complete the questionnaires and pain records. Exclusion criteria Patients will be excluded if they meet any of the following conditions: Pregnancy. Allergy or hypersensitivity to articaine or epinephrine. Uncontrolled systemic disease. Coagulation disorders or medication affecting coagulation. Ability to recognize the anesthetic technique used, for example dental professionals. ASA III or higher systemic status. Drugs or systemic conditions that contraindicate surgery or the use of local anesthetics or vasoconstrictors. Relative or absolute contraindication to the conventional postoperative analgesic or anti-inflammatory regimen. Randomization Randomization will be performed using a computer-generated sequence. The allocation sequence will be prepared through randomization software and placed into opaque, sequentially numbered envelopes. Each envelope will contain the treatment allocation: either the experimental group, corresponding to IANB, or the control group, corresponding to TINF. The envelope will be opened immediately before administering the anesthetic technique, ensuring concealment of the allocation sequence. Blinding The study is designed as triple-blind. Several measures will be used to reduce bias: The patient will be blinded to the anesthetic technique. During anesthesia administration, the patient's eyes will be covered with sterile drapes, preventing visual identification of the technique. The surgeon will also be blinded. The surgeon and assistant will leave the operating room while the study investigator administers the assigned anesthetic technique. After anesthesia has been administered, the surgeon will return and perform the surgical procedure without knowing the group allocation. Outcome assessment will be blinded. The investigator who records intraoperative and postoperative variables will be different from the investigator who administered the anesthesia. The statistician responsible for data analysis will also remain blinded to group allocation. Interventions Before recruitment begins, the professionals responsible for administering the anesthesia will undergo calibration to ensure consistency in the application of the anesthetic techniques, particularly the direct inferior alveolar nerve block technique. The percentage of successful blocks may be assessed as part of this calibration. Experimental group: inferior alveolar nerve block Patients allocated to the experimental group will receive: One cartridge of 4% articaine with epinephrine 1:100,000 for the inferior alveolar nerve block. Additional anesthetic for the buccal nerve block. The inferior alveolar nerve block will be performed using the direct Halstead approach, following the technique described by Malamed. The puncture point is located in the mucosa medial to the mandibular ramus. The patient is placed in a supine or semi-supine position with maximum mouth opening. The operator identifies the coronoid notch and the pterygomandibular raphe, using anatomical landmarks to guide needle insertion. The needle is advanced until bone contact is achieved, then withdrawn slightly before anesthetic deposition. The buccal nerve block will be performed by injecting anesthetic into the buccal mucosa distal and buccal to the most posterior mandibular molar area, close to the mucoperiosteum. Control group: infiltrative anesthesia Patients allocated to the control group will receive 4% articaine with epinephrine 1:100,000 using infiltrative anesthesia. The technique will include buccal supraperiosteal infiltration and lingual supraperiosteal infiltration in the area of the implant to be treated. The infiltrative technique is based on local deposition of anesthetic around terminal nerve branches or nerve fibers that are not macroscopically identifiable. Surgical procedure After anesthesia, the surgical treatment of peri-implantitis will be performed by a student from the Master's program in Oral Surgery and Bucofacial Implantology. The surgical approach may be resective, regenerative, combined, or associated with soft tissue procedures, depending on the clinical characteristics of the peri-implant defect. The surgical procedure may include flap elevation, debridement and removal of granulation tissue, decontamination of the implant surface, bone treatment such as ostectomy or regeneration, soft tissue procedures, and suturing. The surgeon will record whether re-anesthesia is required, the type of additional anesthesia used, the stage of the procedure at which it is needed, the amount of additional anesthetic administered, the duration of the surgery, and the difficulty of the procedure. Study visits The study includes three main visits. First visit During the first visit, the patient's full medical history will be obtained and a clinical examination will be performed. Complementary diagnostic tests will be requested if necessary. A diagnosis will be established and a treatment plan will be proposed. If the patient meets the inclusion and exclusion criteria, the study and surgical procedure will be explained. The patient will be asked to sign a specific informed consent form for participation in the clinical trial, in addition to the consent form for the surgical intervention. Second visit During the second visit, surgical treatment of peri-implantitis will be carried out. Before surgery, the patient will complete a modified dental anxiety questionnaire, the Modified Dental Anxiety Scale. The surgical field will be prepared with sterile drapes. The patient's eyes will be covered, and the surgeon and assistant will leave the operating room. The investigator responsible for anesthesia will then enter, open the randomization envelope, and administer the assigned anesthetic technique. After the anesthetic procedure, the surgeon will return and perform the peri-implantitis surgery while remaining blinded to the allocation group. At the end of the intervention, postoperative instructions will be given verbally and in writing. These instructions include following a soft or semi-liquid diet, using intermittent cold application, maintaining good oral hygiene, and following the prescribed medication regimen. The postoperative medication protocol includes ibuprofen according to body weight, chlorhexidine 0.12% mouthrinse, and paracetamol as rescue analgesic. Antibiotics will only be used if the clinical investigator diagnoses postoperative infection or considers them necessary according to clinical judgment. Before leaving the center, the patient will receive forms to record postoperative pain using visual analogue scales and to report medication intake and any need for sick leave. Third visit The third visit will take place between 7 and 9 days after surgery. During this postoperative control visit, the patient will return the pain diary and report rescue medication intake and any sick leave. The visit will also include a global subjective assessment of the intervention using a verbal rating scale, clinical examination of the surgical wound, suture removal when appropriate, oral hygiene instructions, and recording of adverse events, complications, and changes in concomitant medication or health status. In regenerative or combined surgical cases, suture removal may be delayed according to the clinical protocol. Primary outcome The primary outcome is anesthetic efficacy, defined as the absence of need for re-anesthesia during the surgical procedure. This outcome will be recorded as a dichotomous variable: yes or no. Secondary outcomes and variables The study will collect several categories of variables. Patient-related variables These include: Age. Sex. Systemic diseases. Current chronic or recent medication. Smoking habit. Dental anxiety measured using the Modified Dental Anxiety Scale. Preoperative variables These include: Mouth opening measured in millimeters. Intraoperative variables These include: Assigned group: experimental or control. Type of surgery: resective, regenerative, or combined. Need for re-anesthesia. Surgeon experience. Number of implants treated. Implant position. Intraoperative pain measured by a 10-cm visual analogue scale. Pain during injection measured by a 10-cm visual analogue scale. Duration of the procedure, from incision to final suture. Intraoperative adverse events. Potential intraoperative adverse events include disorientation, dizziness, blurred vision, nausea, vomiting, tremors, seizures, and vasovagal syncope. Postoperative variables These include: Postoperative pain measured using visual analogue scales at 2 hours, 6 hours, 12 hours, 24 hours, and daily up to day 7. Duration of anesthesia in minutes. Rescue medication intake. Need for sick leave. Wound healing. Postoperative complications. Patient-reported experience and satisfaction. Postoperative complications include paresthesia, bleeding, hematoma, trismus, delayed wound healing, wound dehiscence, and other local or systemic events. Trismus will be assessed as the difference between preoperative and postoperative unassisted mouth opening, measured in millimeters. Patient-reported measures The study includes patient-reported experience measures focused on the anesthetic and surgical experience. Patients will evaluate statements such as whether they felt pain during the procedure, whether anesthesia was sufficient to allow comfortable treatment, whether administration of anesthesia was comfortable, whether postoperative numbness was adequate, whether the duration of anesthesia was as expected, whether unpleasant sensations occurred after anesthesia, and whether they were satisfied with the anesthesia received. Patients will also report whether they would repeat the same type of anesthesia in the future and whether they would recommend it. Additional satisfaction questions will address pain control during surgery, satisfaction with the surgical treatment, pain control after returning home, willingness to recommend the surgery, and willingness to repeat the procedure. Sample size The study is considered a pilot exploratory trial because there are no previous clinical studies specifically evaluating these anesthetic techniques in the context of surgical treatment of peri-implantitis in posterior mandibular implants. The primary variable, need for re-anesthesia, is binary. Due to the lack of precise estimates for this clinical setting, a definitive confirmatory sample size calculation is not possible with robust assumptions. The proposed sample size is 30 patients, with 15 patients in each group. This sample is considered appropriate for the methodological and clinical objectives of a pilot randomized trial. It will allow the researchers to estimate preliminary rates of re-anesthesia, assess safety, evaluate feasibility of recruitment and blinding, and generate data for a future confirmatory trial with adequate statistical power. For patients with multiple mandibular implants affected by peri-implantitis, only one implant will be selected for inclusion in the statistical analysis. The selected implant will be the one with the greatest clinical severity, based on probing depth or radiographic bone loss. If several implants show similar severity, selection will be randomized. This is intended to ensure independence of observations and avoid bias due to within-patient correlation. Statistical analysis Data will be processed using Stata/IC 15.1. All variables will be presented stratified by treatment group. Descriptive statistics will be selected according to the nature and distribution of the variables. For quantitative variables, normality will be assessed using the Shapiro-Wilk test and visual evaluation of P-P plots and box plots. If the normality assumption is met, results will be described using mean and standard deviation. If not, median and interquartile range will be used. The number of valid observations and the variable range will also be reported. Qualitative variables will be summarized using absolute frequencies and relative percentages. The primary outcome, need for re-anesthesia, will be compared between the IANB and TINF groups. Depending on data distribution and variable characteristics, appropriate statistical tests will be applied. Safety outcomes will be analyzed by comparing the incidence of adverse events between groups using chi-square tests or Fisher's exact tests. Repeated-measures analysis will be used to evaluate the evolution of pain over time. Statistical adjustment may be performed to control for potential confounding variables. Statistical significance will be set at p \< 0.05. Ethical considerations The study will be conducted according to the ethical principles of the Declaration of Helsinki and applicable Spanish and European regulations governing clinical research and data protection. Participation will be voluntary and will require explicit written informed consent. Patients will be informed about the study, the surgical procedure, and their right to withdraw at any time without affecting the continuity or quality of their treatment. Patient anonymity will be preserved. Patient names will not appear in study documents; instead, each participant will be identified using a study code. Data will be reported in aggregate form, and individual identities will not be disclosed in publications or conference presentations. Informed consent documents and study databases will be securely stored. The collected data will be kept on an encrypted hard drive and stored under secure conditions. No specific insurance is considered necessary for participation in the study according to the protocol. Timeline The recruitment period is planned to last approximately one year. Data processing will take place after completion of recruitment and follow-up, followed by manuscript preparation. Expected contribution This study is expected to provide preliminary clinical evidence regarding whether IANB or infiltrative anesthesia offers better anesthetic performance for peri-implantitis surgery in the posterior mandible. Its results may help determine whether infiltrative anesthesia with articaine can be considered a reliable alternative to IANB in this context, or whether IANB remains the more predictable option for complex posterior mandibular peri-implant surgery. As a pilot trial, the study will also provide important feasibility data. These include recruitment capacity, protocol adherence, effectiveness of blinding, frequency of re-anesthesia, patient tolerance, adverse event rates, and variability of pain and satisfaction outcomes. This information will be useful for designing a larger confirmatory randomized clinical trial. Main limitations The protocol identifies several limitations. First, anesthesia will be administered by only two calibrated investigators. This may improve standardization and internal validity but may reduce external validity, since the results may not fully reflect the variability expected among different clinicians. Second, surgeries will be performed by master's students, whose surgical experience may be limited or variable. This could influence surgical duration, difficulty, intraoperative discomfort, and the need for re-anesthesia. Third, although only one implant per patient will be included in the statistical analysis, some procedures may involve multiple implants or more extensive surgical areas, potentially increasing surgical duration and influencing anesthetic outcomes. Despite these limitations, the study addresses an important gap in the literature and may contribute to more evidence-based anesthetic decision-making for peri-implantitis surgery in posterior mandibular implants.