TuttleNumbNow (TNN; TuttleNumbNow LLC, Provo, UT, USA) is a training system that introduces the TNN intraosseous (IO) injection as a primary injection to achieve profound pulpal anesthesia without the use of a specialized port or handpiece [1, 2, 3]. The complete TNN anesthesia protocol begins with IO injections, followed by local infiltration and, if necessary, resorting to an inferior alveolar nerve block (IANB) (TNN Training Manual, 2021). The protocol is designed to numb teeth more effectively, efficiently, and at reduced pharmacological doses compared with traditional IANB.

IO anesthesia has been studied extensively and previously evaluated as a primary anesthetic technique [4, 5, 6, 7, 8]. However, currently available IO systems require the use of specialized perforation devices such as X-tip^® or Stabident^® (which is no longer available) [9, 10], or a dedicated handpiece (Anesto, Intraflow, QuickSleeper 5), which can increase costs, add logistical complexity, and limit accessibility [11, 12]. The TNN IO injection overcomes these limitations by eliminating the need for costly armamentarium, instead utilizing a standard syringe, a 30-gauge Septoject^® Evolution (Septodont, Lancaster, PA, USA) needle, and a TNN needle guide [13]. This patented technique emphasizes operator skill rather than computerized delivery; accordingly, proper training is critical for successful implementation [1, 14]. An unpublished internal survey of 107 providers who purchased a TNN training kit in 2017 reported that IO anesthesia use increased substantially, with daily use increasing from 4% prior to training to 49% after training [15]. This shift in practice suggests that the TNN protocol may be more readily adopted as a primary anesthetic technique. However, its clinical efficacy remains an area of active investigation [14, 16]. The present study evaluated the efficacy of the TNN anesthesia protocol in achieving profound clinical anesthesia in the mandibular first molars.

The current standard practice for anesthetizing mandibular first molars is IANB [2, 17]. Although commonly used and taught as a standard of care, IANB has significant limitations [18, 19]. Success rates can be inconsistent because anatomical variations can result in failure to access the mandibular foramen or failure to account for accessory innervation [20, 21]. Owing to the delayed onset of anesthesia (8 min on average), clinical efficiency is reduced, and anesthesia failures can become increasingly inconvenient [22]. In addition, large doses of anesthetics may be used, resulting in an increased practice overhead and an increased likelihood of approaching a toxic threshold [23]. Furthermore, IANB can lead to prolonged, undesired collateral numbness in the lips, cheeks, and tongue, increasing the risk of inadvertent injury postoperatively and decreasing patient satisfaction [19]. Uncommon but severe risks associated with IANB include infection or bleeding within the mandibular foramen, needle migration, and jaw paralysis [24, 25]. These risks are exacerbated by limited cooperation among pediatric or anxious patients. The shortcomings of IANB suggest that the current standard of care is not ideal. By contrast, IO anesthesia offers the potential for rapid-onset, site-specific anesthesia with a more predictable clinical response at a reduced dose and minimal collateral numbness [4].

The TNN protocol is a stepwise algorithm designed to provide a systematic approach to dental anesthesia, with each step numerically designated from TNN1 to TNN10 (Fig. 1). The injections are administered sequentially until adequate clinical anesthesia is achieved. After each step, pulpal anesthesia is determined based on patient feedback, although cold testing could also be performed. To anesthetize the mandibular first molar, the protocol begins with an IO injection distal to the tooth (TNN1), followed by an IO injection at the mesial site (TNN2; Fig. 2). If profound pulpal anesthesia is not achieved, the protocol recommends buccal infiltration (TNN3), followed by lingual infiltration (TNN4). Each injection from TNN1 through TNN4 utilizes 0.45 mL (one-quarter cartridge) of articaine 4% with epinephrine 1:100,000. If adequate pulpal anesthesia is not obtained after completion of TNN1–4, the same injection sequence is repeated using 0.45 mL (one-quarter cartridge) of mepivacaine 3% without epinephrine at each site (TNN5–8). In patients with a documented history of difficulty achieving profound anesthesia, clinicians may elect to initiate the protocol with TNN5–8, followed by TNN1–4, if necessary. When additional supplementation is required, four periodontal ligament injections (TNN9) are administered, one at each line angle, using 0.11 mL (one-sixteenth cartridge) of articaine 4% with epinephrine 1:100,000 at each site [3]. Finally, as a last resort, IANB (TNN10) is administered using 1.8 mL (one full cartridge) of mepivacaine 3% without epinephrine. Notably, this protocol represents a departure from conventional practice by reserving IANB as a last-line intervention rather than a first-line anesthetic technique.

Fig. 1
TuttleNumbNow anesthesia protocol for symptomatic irreversible pulpitis (“hot tooth”) (TNN Training Manual, 2021). Reproduced with permission. Injection efficacy rates are determined as described by Reader et al. [3]. Abbreviations: PDL, periodontal ligament injection; IA, infiltration anesthesia; IANB, inferior alveolar nerve block

 

Fig. 2
TNN2 injection of the mandibular first molar at the mesial site. Second injection using the TuttleNumbNow protocol (TNN2) is placed at the mesial site of the mandibular first molar. A 30-gauge Septoject Evolution needle is used in conjunction with the TNN needle guide. The needle is advanced into the lingual plate to a depth of 9 mm.

 

A previous study has reported modest success rates with a single TNN IO injection, comparable to a single infiltration when performed by a single operator [16]. However, as described in the protocol, more than one injection may be necessary to achieve pulpal anesthesia [14]. In addition, the counterintuitive nature of this technique suggests that adequate training is necessary to improve success rates and reduce complications [14]. Thus, it is necessary to evaluate the efficacy of the TNN anesthesia protocol as a whole when performed by an experienced operator [14].

The present study aimed to evaluate the clinical effectiveness of the TNN anesthesia protocol for mandibular first molar procedures based on a retrospective analysis of patient records over a 1-year period.

This retrospective observational study analyzed data from Tuttle Family Dental, a private dental practice in Orem, Utah. The study period encompassed procedures performed between January 1, 2023 and December 30, 2023. All dental procedures during this timeframe were performed by a single provider (GKT), the sole proprietor of Tuttle Family Dental and TuttleNumbNow LLC. To avoid conflicts of interest, data were collected by an office manager (LB) and analyzed by external researchers (CKN and JJT).

Electronic dental records from the Eaglesoft Dental Practice Management software were screened using the Current Dental Terminology procedure codes to identify eligible cases. The inclusion criteria were patients who received the TNN protocol and underwent one of the following procedures on a mandibular first molar: composite restoration (D2391, D2392, D2393, D2394), crown preparation (D6085), or crown seat procedures. Extractions, implants, and root canals were excluded as they were often referred to specialists. Additionally, sealants, tooth shaping, and procedures not requiring local anesthesia were also excluded.

Data were extracted from the Eaglesoft system to determine the procedure performed and details of the anesthetic administration. Operative notes were reviewed to assess the method of anesthetic administration and anesthetic agents used. Each case was categorized based on the anesthetic regimen required to achieve adequate anesthesia: no anesthetic needed, single-agent TNN protocol (articaine 4% with epinephrine 1:100,000 or mepivacaine 3% without epinephrine), dual-agent TNN protocol, and conversion to IANB.

The study was reviewed by the Institutional Review Board of the University of Texas Health Science Center at San Antonio and determined to be non-regulated human research as the analyzed dataset was completely de-identified (STUDY00001752). The study was conducted in accordance with the principles of the Declaration of Helsinki.

Descriptive statistical analysis was employed to summarize the distribution of procedure types and anesthetic regimens. The key variable of interest was the frequency of cases requiring conversion to IANB after the initial TNN protocol application. The associations between procedure type and the necessity for IANB were evaluated using Fisher's exact test. Statistical significance was set at P < 0.05.

The records of 1,040 patients were reviewed. Of these, 184 met the inclusion criteria and were included in the final analysis. The distribution of the procedures was as follows: 74 composite restorations, 57 crown preparations, and 53 crown seat appointments (Fig. 3).

Fig. 3
Distribution of procedure types included in the analysis. The composite restorations group comprises one-surface (n = 42), two-surface (n = 19), three-surface (n = 12), and four-surface (n = 1) procedures.

 

Regarding anesthetic use for the first mandibular molars, 47 procedures (25.5%) were completed without local anesthesia. Of the 137 cases that required anesthetic administration, 88 cases (64.2%) required a single anesthetic agent (TNN1–4 or TNN5–8 alone, 0.45–1.8 mL total), 41 cases (29.9%) required a combination of two anesthetic agents (TNN1–8, 1.8–3.6 mL total), and 8 cases (5.8%) required an IANB (TNN1–10) (Fig. 4). Of the 137 cases requiring anesthesia, 129 (94.2%) were successfully managed without the need for IANB, indicating a 94% success rate of the TNN protocol in achieving profound anesthesia without falling back to traditional nerve block techniques.

Fig. 4
Distribution of anesthetic regimens required for 137 mandibular first molar cases treated using the TuttleNumbNow (TNN) anesthesia protocol. TNN1–4 uses articaine 4% with epinephrine 1:100,000, whereas TNN5–8 uses mepivacaine 3% without epinephrine. The specific number of steps administered per case was not recorded. Abbreviation: IANB, inferior alveolar nerve block

 

The need for IANB was significantly associated with the procedure type (P = 0.0008). Of the 8 cases that required IANB, 7 were crown preparations (12.3%, 7 of 57 crown preparation cases), and 1 was a crown seat (1.9%, 1 of 53 crown seat cases). All composite restorations (n = 74) were completed without the use of IANB.

The current standard anesthetic treatment for mandibular first molar procedures is IANB [26], and IO injections are used only when IANB fails to provide sufficient pulpal anesthesia. This study focused on the use of IO and infiltration injections as first-line anesthetic modalities using the TNN protocol. The results of this study indicate that the TNN protocol is effective as a primary anesthetic modality for mandibular first molar procedures. Among the 137 mandibular first molar cases requiring anesthesia, 94% of patients were able to receive care without requiring the application of an IANB. This underscores the effectiveness of the technique in routine clinical practice. These findings support the pharmacological principle of distributing a minimally effective dose, which is defined as the smallest dose that can achieve a clinically significant response. In this study, 64% of the patients required only one cartridge or fewer of the anesthetic, with only 5.8% requiring three cartridges. The high success rate of the TNN protocol in achieving clinically effective anesthesia without resorting to IANB indicates that less invasive anesthetic techniques can be utilized in dental procedures, minimizing the patient’s exposure to anesthetic agents.

These findings are important for the broader field of dentistry because they allow for minimally invasive, comfortable, and efficient patient care. IANB, which is traditionally regarded as the gold standard for mandibular anesthesia, has several logistical drawbacks. It has a delayed onset, occupying both the patient and provider time while waiting for the anesthetic to take effect. The use of IO injections eliminates this waiting time, creating a more efficient experience for both patients and providers [27]. With TNN IO injection, there is no waiting time for the patient to achieve numbness. Immediately following the injection, the dentist can assess the pulpal anesthesia and proceed with the dental procedure. IANB also results in a large area of anesthetic effect, increasing the risk of inadvertent, self-inflicted soft-tissue injury post-operatively [28]. Furthermore, extended soft-tissue anesthesia involving the lips, cheeks, and tongue may adversely affect patient satisfaction by interfering with normal activities [29]. By contrast, IO anesthesia, as achieved using the TNN protocol, is more localized, minimizing these risks. The success of the TNN protocol indicates that IO anesthetic delivery can transition from a secondary rescue technique to an effective first-line approach. Implementing this shift in standard practice may increase patient comfort, improve procedural efficiency, and reduce anesthetic exposure.

The potential complications associated with TNN injections differ from those associated with IANB. The IANB carries well-documented risks, including mechanical injury to the inferior alveolar and lingual nerves, hematoma formation, trismus, and prolonged neurosensory disturbances, largely due to deep soft-tissue penetration near major neurovascular structures [18, 24, 25]. By contrast, TNN is an IO technique that theoretically avoids direct nerve trauma, although data describing its complication profile remain limited. Dolphin et al. reported soft-tissue necrosis when a full carpule of anesthetic was delivered via TNN; however, the recommended protocol limits delivery to approximately one-quarter of the carpule per site, which may reduce this risk [14, 16]. Other complications associated with IO anesthesia that are applicable to TNN include mild injection site discomfort, transient cardiovascular effects related to vasoconstrictor uptake, and a brief bitter taste due to anesthetic backflow [30]. As with other IO techniques, careful execution of TNN injections in accordance with the training manual appears to be important for minimizing complications and achieving favorable patient outcomes [31, 32].

This study has some limitations that should be considered when interpreting the results. First, the retrospective design of this study relied on existing documentation, which limited the ability to control for confounding variables. A prospective study would provide stronger evidence of the effectiveness of the TNN protocol. Patient factors such as age, race, sex, alcohol consumption, smoking status, and concurrent medication use were not included because data were not readily available [33, 34]. The inclusion of these variables could provide insights into circumstances in which conversion to IANB is more likely. Additionally, the anesthetic doses were organized into broad categories; thus, additional studies are required to evaluate the efficacy of each step of the protocol. In addition, future evaluations comparing the success rates of each anesthetic agent would be insightful, as the retrospective nature of the data precluded comparisons in this study. Finally, this study relied on data from a single dental office that frequently refers out complex procedures or medically compromised patients, which may limit generalizability to broader patient populations.

In summary, this study demonstrates that the TNN IO injection is highly effective as a primary anesthetic technique for procedures on mandibular first molars, achieving effective anesthesia in 94% of cases without resorting to IANB. These findings challenge the conventional practice of using IANB as a primary injection and support the use of minimally invasive IO techniques. Future prospective studies are warranted to validate these results, evaluate the effects of other confounding variables, and explore broader applications across diverse patient populations.