930 D3000 new imprint Word template Vol 13, No 1 (2025) ISSN 2167-8677 (online) DOI 10.5195/d3000/2025.930 http://dentistry3000.pitt.edu Neuromuscular Relaxation Using Anterior Leaf Gauge to Quick Guide the Condyles in Proper Position Amal Abdallah A. Abo-Elmagd College of Den*stry, Qassim University, Saudi Arabia and Faculty of Dental Surgery, Misr for Science & Technology University, Egypt Abstract To confirm the centric rela6on (CR), the leaf gauge can be used to load the TMJ. A load test will yield a nega6ve result for a healthy TMJ. Nonetheless, the joint or muscles may be the reason of TMJ disorders if the pa6ent experiences pain, tension, or tenderness, par6cularly in the region in front of the ear or nearby. In addi6on, the mandible can be in a centric rela6onship using a leaf gauge, which is made up of several plas6c leaves. The leaf gauge helps the pa6ent retrude the mandible by posi6oning it between the anterior teeth. The condyles tend to be moved against their menisci by the bi6ng force. Therefore, this review study aims to describe the importance of the leaf gauge for neuromuscular relaxa6on to quick guide the condyles in CR posi6on, to assist the recording of a reproducible jaw posi- 6on during prosthodon6c treatment. Open Access Cita%on: Abo-Elmagd AAA (2025) Neuromuscular Relax- a%on Using Anterior Leaf Gauge to Quick Guide the Con- dyles in Proper Posi%on. Den%stry 3000. 1:a001 doi:10.5195/d3000.2025.930 Received: May 3, 2025 Accepted: May 6, 2025 Published: June 26, 2025 Copyright: ©2025 Abo-Elmagd AAA. This is an open ac- cess ar%cle licensed under a Crea%ve Commons AVribu- %on Work 4.0 United States License. Email: a.aboelmagd@qu.edu.sa Centric relation plays a signi0icant role in oc- clusion and clinical practice to accomplish the relations between joints, muscles, and teeth. Moreover, it has direct effects on maintenance of oral health, prosthetic reha- bilitation, orthodontic and maxillofacial planning, temporomandibular disorder (TMD) therapy, and occlusal rehabilita- tion. Thus, using a CR technique that pro- duces the highest reproducibility of condylar positions in CR is essential [1]. The current de0inition of centric relation is “a maxillomandibular relationship, independ- ent of tooth contact, in which the condyles articulate in the anterior-superior position against the posterior slopes of the articular eminences; in this position, the mandible is restricted to a purely rotary movement; from this unstrained, physiologic, maxillomandib- ular relationship, the patient can make verti- cal, lateral or protrusive movements; it is a clinically useful, repeatable reference posi- tion” [2]. The characteristics of centric relation differ for each individual. The operators must softly, without using any force, direct the mandible posteriorly to the maximum inter- cuspation. Consequently, the components of TMJ (condyles, discs, ligaments, muscles, and physiological limits) will establish the cen- tric relation. The tripod concept is the basis for deprogramming the lateral pterygoid, which is the muscle-releasing tool. When there is a gap between teeth, and fewer teeth are in contact, the lateral pterygoid is re- leased temporally and the muscle memory is erased; hence, the masticatory muscles can help the condyle return to its natural posi- tion [3,4]. Recently, intraoral contactless 3D scanners are used to record CR. A virtual articulator and software program are being used to im- port the analog occlusal record. To construct an occlusal device, the jaw relation records and the virtual occlusal record of the maxi- mal intercuspal position are utilized [5-7]. In fact, there are numerous bene0its of digital recording, in terms of accuracy and ef0i- ciency. For example, there is no intermediary medium present during the recording pro- cess. Moreover, the dental laboratory techni- cian does not need to place the actual stone casts; instead, the digital casts are uploaded into the software in the CR position. This guarantees a precise and effective installa- tion in the virtual articulator. Additionally, the intraoral scanner software compares the digital casts of the arches to the inter-arch scan, which was acquired from the side view of the arches, to perform the direct digital oc- clusal recording. However, the expense of Neuromuscular RelaxaEon Using Anterior Leaf Gauge to Quick Guide the Condyles in Proper PosiEon Vol 13, No 1 (2025) DOI 10.5195/d3000/2025.930 http://dentistry3000.pitt.edu 2 purchasing the intraoral scanner and the learning curve that goes along with it are drawbacks of direct digital recording [8]. In addition, there are common different techniques that can be usually used to record CR. They include graphic techniques, such as gothic arch tracing (intraoral and extraoral); physiologic ones, including tongue retrusion along the posterior part of the palate and swallowing methods; guiding techniques, such as guidance of chin and bilateral manip- ulation; and anterior device techniques, in- volving composite resin stops, an anterior deprogrammer, and a leaf gauge [9-12]. In fact, the anterior device is considered a useful tool since it stabilizes the mandible and does not block the side view of the in- traoral scanner. Besides, because the mandi- ble is more stable when supported by an an- terior device, in comparison to a lateral de- vice, the anterior device technique seems to be simpler and less error-prone than similar techniques. Additionally, the anterior device technique is very ef0icient regarding posi- tioning the condyles in CR by allowing the patient to contract the elevator muscles and relax the lateral pterygoid muscles. Conven- tionally, bimanual manipulating wax rims on base plates, wax wafers, or polyvinyl silox- ane pastes can be used to record CR [12-14]. Previous studies reported that the pres- ence of the two condyles in the articular em- inences (the tripod) help in the stabilization of the mandible; therefore, some researchers prefer to use conventional method with an anterior device, where the mandibles is more stable, and put polyvinyl siloxane while positioning the mandible in CR [4,8]. Many researchers have described a tech- nique that permits a straightforward and precise CR recorded at the chosen OVD and transferred to a virtual articulator . Moreo- ver, a direct intraoral digital scanner is used to record CR. Conventional methods were used to stabilize mandible and determine CR at the required OVD. The position pertaining to the left and right posterior regions of the arches was recorded using an intraoral scan- ner. An anterior composite resin stop for 0ixed prostheses and an occlusal device are constructed using a leaf gauge [8]. Many researchers tried to guide jaw closure and avoid errors in assessing occlusal con- tacts by using two methods, the leaf gauge (1 to 6 mm thick) and the anterior acrylic resin jig, to record centric relation closures. These two methods were adopted to avoid adap- tive mandibular closure patterns [15]. Furthermore, a study was conducted on 0ive healthy adults without symptoms of TMD. The researchers trained the patient to bite with maximum and half-maximum bite force using an anterior jig. Then, they recorded the condylar displacement during clenching with electromyographic activity of muscles of mastication. They found that there was signi0icant decrease in anterior temporalis activity (p<0.05), when compared to the maximum intercuspal clench and maximum clench on a leaf gauge temporalis muscle ac- tivity. Additionally, they concluded that there was no identi0ication for constant change in condylar position [16]. Researchers also studied the use of different planned methods for jaw transfer records to accomplish a superior positioning of the con- dyles, such as leaf gauge, Roth’s power cen- tric relation registration, or anterior jig. These methods depend on the anterior stop to disclose posterior teeth and disregard the tooth contact interfering. They placed sev- eral sheets between the anterior teeth (10 sheets 0.1mm thick) to ensure that the pos- terior teeth are not in contact. They sup- posed that this procedure allows the jaw and condyles to adopt a reproducible position for recording the transfer records for prostho- dontic [17-20]. Moreover, a study considered the centric re- lation records for 40 patients before and af- ter the usage of an anterior 0lat plane depro- gramming appliance (Jig). The Panadent con- dylar path indicator was used to record over- jet dimensions, incisal overbite, and three- dimensional instrument condylar. They found that, the Lucia jig deprogramming ap- pliance offers more movement of centric re- lation record from MI. They concluded that the appliance is more useful in cases where there is a problem in centric relation bite registration. 21 According to other reports, there was minimal antero-posterior compo- nent, and the most superior condylar posi- tion was obtained by heavy biting on an an- terior rigid stop, when com- pared to other techniques [22]. The bimanual manipulation technique is a commonly described technique of recording CRCP, where the dentist supports the mandi- ble through the retruded movement till the patient feels the initial tooth contact (CRCP). This procedure is repeated while using an articulating paper. Many operators suppose this method is subject to worker error; and it is problematic when the mandible is in CRCP [14,23–25]. Clinicians also used discarded panoramic radiography 0ilm to create a sim- ple, low-cost leaf gauge deprogrammer. To prevent posterior occlusal contacts, a depro- grammer is positioned in the anterior region to accomplish muscle deprogramming. Then, the condyles were set in the centric relation position because of the lateral pterygoids re- laxing. Long introduced leaf gauge depro- grammers, which are useful for muscle de- programming [26-28]. On the other hand, there is a pattern of mus- cle activity called engram; it causes the man- dible to de0lect, leading to an error when re- cording the position of the centric relation. To remove this, tools called deprogrammers are used. The condyles should be en- grammed, positioned, and secured in the centric relation position [29]. Therefore, to help dentists achieve precise bite registra- tion in Centric Relation (CR) and occlusal analysis, Huffman created the Leaf Gauge in 1970. It offers a quick and easy way to reg- ister for bites in CR. It is a set of 56 strips made of 0lexible plastic leaves, each measur- ing 0 to 1 mm. Its design has not considera- bly changed, which re0lects how useful and successful it is in clinical settings. In clinical practice today, it is still a commonly used tool [30]. A leaf gauge consists of multiple smooth, 0lexible plastic sheets arranged together on top of each other; the thickness of each leaf is around 0.1 mm. It is used to detect centric re- lation. It is placed along the midline of the an- terior teeth to separate the posterior teeth retruding the mandible and to offer a suita- ble record of the precise vertical opening be- tween the incisors. According to the case, the vertical opening will be controlled through in- creasing or decreasing the number of sheets. When the patient is applying pressure on the leaf, the biting force tends to move the con- dyles against their eminence. The position of the mandible does not exceed physiologic limits. The Leaf gauge is placed in the pa- tient’s mouth during retruding for occlusal equilibrium. Moreover, it is utilized to do fast deprogramming, to identify the first point of CR contact, and to record CR posi- tion. However, it is contraindicated in cases of a deep overbite with strong elevator mus- cles, where the flexible gauge can exert a Neuromuscular RelaxaEon Using Anterior Leaf Gauge to Quick Guide the Condyles in Proper PosiEon Vol 13, No 1 (2025) DOI 10.5195/d3000/2025.930 http://dentistry3000.pitt.edu 3 force on the condyle [15,31,32]. Kwiecien also lists several uses for a leaf gauge; they include obtaining bite records for centric re- lations, loading the TMJ, deprogramming the lateral pterygoid, and identifying the 0irst point of contact in centric relation [4]. Additionally, there are steps for leaf gauge application. First, several leaves (about 5 to 8) are placed anteriorly in the maxillary cen- tral incisors along the midline, parallel to the palatal plane. Then, the patient is asked to close the mouth till the lower incisors contact the underneath of the leaf gauge, with no contact in the posterior region. Moreover, more leaves can be added to get posterior separation. Next, the patient is in- structed to move the lower jaw for- ward/back and hold down onto the mylar strips, without any posterior molar contact. The number of leaves used is controlled based on the patient’s response. After that the patient is requested to grasp the gauge in place for 2 to 5 minutes. Subsequentially, A-Silicone bite registration paste is used [33]. Prior to that the patient moves his jaw forward and backward and squeeze lightly (half-hard bite); the leaf gauge is placed be- tween his upper and lower centrals while he is in a supine position. This bite only acti- vates the temporal muscle, not the masseter, to prevent the mandible from protruding [4]. The opening must remain within the arc of closure (rotation) while enough leaf gauges are used to maintain the back teeth apart and create a smooth path. Furthermore, a dis- tinct vertical component can be created by too few leaves, especially if the patient has a deep overbite. On the other hand, the con- dyle is forced down the eminence, beyond rotation, by too many leaves, which would feel heavy and possibly too open (transla- tion). Two sets of leaves can be used to meas- ure the amount that needs to be increased in vertical dimension (VD) [34]. The operator can record the quantity and di- rection of the slide using a leaf gauge, whether vertical, horizontal, or lateral. To measure the slides, the leaf gauge is moved laterally. In the anterior/posterior position, the facial of the same lower incisor is to the incisal edge of the same upper incisor. For the vertical position, the incisal edge of the same upper incisor is adjacent to the free gingival margin of the same lower incisor. All three positions should be measured using the same reference point for 0irst tooth con- tact and MIP [35]. Obviously, many advantages were recorded by authors for using a leaf gauge. First, there is no need for management by the dentist because the patient can seat the condyles into centric relation using his own muscula- ture. Moreover, the biting is concentrated on the leaf gauge rather than on the wax or ar- ticulating paper. This results in relaxing the jaw muscle and sometimes relieving pain due to continuous strong incisor contact on the leaf gauge for 1 to 5 minutes, allowing the jaw to retrude, which is a more relaxed position, and eliminating the periodontal ligament proprioception. Furthermore, a leaf gauge can be used with an articulating paper to predict which teeth will touch in a centric relation. If a deflective contact is pre- sent, it will be easier to determine whether the mandible is deviating from its typical path of closure. Besides, accurate occlusal analysis and bite registration are provided by a leaf gauge. In addition, a leaf gauge is simple for both patients and dentists to use. It can be also autoclave sterilized, and it can be used for a range of dental procedures. However, it is challenging to use on pa- tients who have deep bites, anterior cross bites, or anterior mobile teeth. Additionally, if the condyle is overly rigid, it may shift pos- terior to CR, or some patients may attempt to bite off a sandwich by protruding their mandible anterior to CR by biting on the leaf gauge slightly forward [12,25,36- 41]. In addition, numerous studies have tried to recognize the effects of a leaf gauge on the activity of (EMG) jaw muscle electromyo- graphic. Hickman et al. 1993 found that a leaf gauge showed the lowest activity of an- terior temporalis and masseter, when com- pared with three methods of jaw relation (manually guided centric relation position, maximum intercuspation, and neuromuscu- lar guided position). Moreover, other stud- ies have documented the condylar displace- ment during a leaf gauge biting. They re- ported that the leaf gauge led to superior condyle displacement with slight antero- posterior displacement [42,43]. Previous re- searchers also stated that the masseter mus- cles were lesser involved than the tem- poralis muscles, when a leaf gauge was used for interocclusal recording [20]. References [1] de Moraes Melo Neto C L, da Silva E VF, de Sousa Ervo- lino I C, Dos Santos D M, de Magalhães Bertoz A P, Goiato M C. Comparison of different methods for obtaining cen- tric relation: a systematic review. Gen Dent. 2021;69(01):31–36. 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