October 2013, Volume 9, Issue 10
Published by AEGIS Communications
Enhancing CAD/CAM Restorations with Onpharma’s Buffering Products
Chairside buffering and reduced anesthetic wait times mean more efficient same-day restorations
When performing CAD/CAM restorations, the goal is to complete the restoration in a single appointment to maintain efficiency. The introduction of a new anesthetic buffering technology by Onpharma Inc. (www.onpharma.com), should help to achieve this goal, and for this reason will likely be appreciated by both dentists and patients. Onpharma’s buffering products eliminate the interruption normally caused by anesthetic wait time, making it possible for practices to adopt a preferred “stay-with-the-patient” workflow model. Because dentists do not need to de-glove and leave the operatory after the injection when using buffered anesthetic, productivity and profitability can be enhanced. These effects are all the more pronounced when Onpharma’s products are used with CAD/CAM restoration technology.
Benefits of Buffered Anesthetic
Onpharma’s products allow the dentist to perform chairside anesthetic buffering immediately before delivering the injection, which reduces the anesthetic wait time to 2 minutes or less. Using traditional anesthesia-delivery methods, the typical anesthetic wait time is a minimum of 10 minutes and generally lasts longer for patients receiving mandibular nerve blocks. Clinicians may use this break to tend to nonpriority tasks such as answering e-mails, diagnosing radiographs, or preparing treatment plans. These tasks may stretch the interlude to 20 minutes or more, taking time away from the patient and lengthening the appointment. Completing every procedure without interruption would clearly be preferable, but it is particularly helpful in the case of CAD/CAM restorations. The introduction of Onpharma’s buffering technology now allows dentists to confidently schedule and perform single-visit restorations.
Using Onpharma’s three products, a dentist can begin the appointment; glove up; administer buffered anesthetic; put on scopes, battery pack, and ear plugs; confirm the effectiveness of the anesthesia; and start the procedure immediately, completely eliminating any need to leave the patient’s side. The reliable 2-minute onset interval is exceptionally helpful in the event that the dentist misses a mandibular nerve block, as the dentist can simply make the clinical decision to re-inject in 2 minutes, and then begin the procedure 2 minutes later. This short interval eliminates the risk of a 20-minute delay that can otherwise disrupt an entire morning or afternoon schedule.
Time Savings with Chairside Anesthetic Buffering
An anesthetic’s pH affects its onset of action. Commercial local anesthetic cartridges are purposefully formulated as acidic solutions in an effort to prolong product shelf life.1 Although physiologic pH is 7.4, commercial lidocaine solutions typically have a pH of approximately 3.9.2-4 Normally, the body buffers the local anesthetic after injection toward physiologic pH, 5 which eventually increases the availability of deionized anesthetic.6 Over time, as this in vivo buffering process continues, more and more of the active form of the anesthetic becomes available, ultimately resulting in nerve blockade. The novelty of Onpharma’s products (Figure 1) lies in their ability to provide the practitioner with a simple, convenient way to buffer the anesthetic precisely and immediately before the injection ex vivo (outside the body). This eliminates any need for the patient’s body to buffer the anesthetic. The ex vivo buffering employed by Onpharma’s products results in rapid onset of analgesia and less injection pain for patients.
Patient Presentation and Assessment
Tooth No. 2 had an existing three-surface composite resin restoration that was failing, with recurrent decay on the distal extending onto the pulpal floor (Figure 2). After removing the composite and decay, all cusps were undermined and unsupported. The patient chose to have the failing restoration replaced with a full-coverage, all-ceramic crown.
Treatment began with a buccal infiltration of 2% lidocaine with 1:100,000 epinephrine buffered using Onpharma’s products. Less than 2 minutes after the injection, the dentist confirmed the efficacy of the analgesia and was ready to begin the procedure. The clinician immediately began removal of the previous restoration and decay, during which the patient experienced no discomfort. When removal of the restoration was complete, 4% chlorhexidine gluconate was applied, followed by Gluma® Desensitizer (Heraeus Kulzer Dental US, www.heraeus-dental-us.com); the patient rinsed after each application. The remaining tooth structure was built up with Geristore® (DenMat, www.denmat.com) and bonded with Scotchbond™ Universal Adhesive (3M ESPE, www.3m.com).
The dentist began preparation using a 5811.033 (Komet USA, www.kometusa.com) extra-coarse occlusal reduction bur and addressed the axial walls with a 5684KR.025 (Komet USA) course, modified, tapered shoulder bur. After the buildup was completed, the initial gross reduction took only a few minutes. An assistant then placed a gingival retraction material (either an 02 braided gingival retraction cord or a diode laser could be used). A product such as the Traxodent® Hemodent® Paste Retraction System (Premier, www.premusa.com) may be used when additional hemostasis or tissue management is required. Typically, the tissue immediately retracts, allowing the dentist to refine the preparation without impinging on the gingiva and causing bleeding. This is important for time savings and for optical scanning.
The dentist completed the preparation using a 6877K.018 (Komet USA) course chamfer bur with refinement using a 8951KR.017 (Komet USA) fine, modified, tapered chamfer bur. At this point, the tooth was ready for scanning and fabrication.
The following is a typical time allocation scenario from start to finish for a single-tooth CAD/CAM crown procedure using Onpharma’s sodium bicarbonate buffering solution, during which the dentist remains active and in the operatory, except while the crown design and milling is taking place.
8:30 AM – The staff reviews the patient’s medical history with the patient, obtains informed consent, and prepares a triple tray impression of the tooth.
8:40 AM – The dentist enters the treatment room, greets the patient, and reviews the scheduled procedure. The dental assistant prepares the anesthetic injection by buffering a cartridge of lidocaine and epinephrine using Onpharma’s products. The clinician delivers the injection, does not de-glove, and does not leave the chair, but instead stays with the patient.
8:42 AM – At 2 minutes post-injection, the dentist checks the efficacy of the anesthesia. If the patient is not numb, the dentist re-injects, waits 1 minute, confirms anesthesia, and begins the procedure.
9:15 AM – The dentist completes tooth buildup, crown preparation, and gingival packing (Figure 3). At this point, the dentist leaves the operatory and the staff scans the tooth using the E4D Dentist (E4D Technologies, www.e4d.com) scanner.
9:50 AM – The dentist returns to the operatory when the E4D unit has completed milling the IPS e.max® CAD (Ivoclar Vivadent Inc., www.ivoclarvivadent.us) crown. The clinician completes the initial try-in, adjusts contacts and occlusion if needed, and uses a digital radiograph to confirm a proper fit.
10:10 AM – Stain and glaze is added to the crown in the blue block phase, and then placed in a ceramic oven for sintering and glazing.
In this example of a CAD/CAM procedure timeline, use of Onpharma’s buffering products allows the design and mill steps to be completed more quickly and reliably, and shortens preparation time. This benefit is of particular relevance in the case of CAD/CAM procedures, which can be relatively lengthy. In general, buffered anesthetic allows any restoration to be started sooner and completed with fewer (if any) operatory entries and exits by the dentist. This results in more efficient and more profitable restorative procedures, while creating a new sense of focused attention that patients have not experienced, and that they appreciate.
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3. Hinshaw KD, Fiscella R, Sugar J. Preparation of pH-adjusted local anesthetics. Ophthalmic Surg. 1995;26(3):194-199.
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5. Gardner JH, Semb J. The relation of pH and surface tension to the activity of local anesthetics. J Pharmacol Exp Ther. 1935;54:309-319.
6. Tuckley JM. The pharmacology of local anaesthesia agents. Update in Anesthesia. 1994;4:19-21. http://e-safe-anaesthesia.org/e_library/03/Pharmacology_of_local_anaesthetic_agents_TOTW_101_2008.pdf. Accessed June 1, 2013.
About the Author
Ron Bosher, DDS