Bite registration procedure. Chapter 3 and the DVD illustrate how to do this, looking both from in front and from the side of the patient. There may be a few millimetres discrepancy between the patient’s real hinge axis and that determined by an earbow. Whatever the cause, the principles of examining and adjusting the occlusion are the same. Kaufman M, Cranin AN, Sayed A, Ley J, DeGrado J, Banton B. the occlusal relationship between the abutment tooth and its antagonist using CAD software. One solution is to construct an acrylic stent or bar; this acts as a rigid vehicle to carry registration material, thereby avoiding the less reliable wax occlusal rims. Casts mounted in ICP – even hand-held casts – might provide some useful diagnostic information, but remember they give no information on deflective contacts and, at best, limited information on guidance and excursive interferences. It is used as a feeler gauge between occluding teeth. The important thing to remember about this type of material is that it needs to be trimmed, whether it is being used as a sectional or full-arch registration (Fig 8-11a,b). All these factors can make it impossible to locate and record a reproducible, let alone relevant, position. Occlusal is a special solution which can be easily applied to the wart, dries quickly, needs no plasters and if used properly should cause minimal irritation. If the styli marks from all three registrations correspond, you can be confident about the registration. Most probably, however, occlusal factors and details of occlusion are in general of minor importance for the outcome of implant restorations. The foils are much easier to use if held in Miller’s forceps to stop them crumpling. They should be so shaped that they represent the lost teeth and supporting structures. As discussed in the previous section, this is the position used typically for the construction of restorations conforming to an existing occlusion. Rather than linking opposing copings together, the upper copings are made with a rounded occlusal excrescence, which is coated in petroleum jelly. There are “good” contacts, which support the occlusion and guide jaw movement, and “bad” contacts, which deflect jaw movement during closure or interfere with excursions. As discussed in Chapter 7, it is also good practice to check all patients for signs and symptoms of temporomandibular disorders (TMDs), particularly those patients requiring extensive restorations. 1997 Jun;24(6):426-32. doi: 10.1046/j.1365-2842.1997.00507.x. The new ICP is sometimes termed “centric occlusion”, which is defined as the occlusion that occurs in CR. An elegant way of doing this is shown in Fig 8-20. An irregular, broken or dog-legged appearance suggests an interference, either on the tooth itself or on a tooth distant to it (Fig 8-6a,b). Precious time can be lost adjusting the occlusal surface of a crown because the opposing alginate impression was distorted or carelessly recorded, making for unnecessary expense, and the clinical outcome can be compromised. • First method : the patient is instructed to wear the occlusal rims continuously for 24 hrs excepting when eating and drinking hot or chilled drinks. The procedure involves using 0.0005-inch thin occlusal registration strips (Artus Corporation, Englewood, NJ) to help verify that the patient is actually closed in centric occlusion. Another important point is that a silicone mousse records surface detail very well, often better than the material used to record the impressions. The technique for the transfer of implant and abutment position to a working cast has been hindered by multiple transfers and record reproductions. Each registration is placed in turn between the casts mounted on the instrument and four styli marks are made – two horizontal and two vertical – representing a notional terminal hinge axis. The bite registration captures the static occlusion. Waxes are available in various consistencies, ranging from the comparatively soft, through pink modelling wax to hard wax. Sometimes the situation can be improved by first marking the teeth with a thicker paper, which leaves a broad smudge of colour against which the contrasting colour of the finer foil can be seen. In essence, the jig, cotton wool roll or tongue spatula encourages the neuromuscular system to “forget” the ICP, the memory of which is reinforced by proprioceptive feedback every time the patient swallows. With practice the procedure becomes second nature. Before looking at mandibular excursions, the ICP can tell you quite a lot about guidance. After placement, the recording medium must remain in position without/>, Box 14.1 Requirements of an occlusal registrationmaterial, Click to share on Twitter (Opens in new window), Click to share on Facebook (Opens in new window), Click to share on Google+ (Opens in new window), on 14: Occlusal (bite) registration materials, 1: Properties of materials—tensile properties, 36: Provisional filling materials and restorations. With this technique, distortion is minimised as there is no cross-arch recording and the record is small enough to minimise the risk of it not seating. Some facebows come as two main components – the bow and the bitefork – with a clamping mechanism to join the two together. Fig 8-1 The patient shown on the DVD reported a clear history of occlusal changes during pregnancy which, despite an excellent periodontal condition, had not resolved over a year later. In order to determine the variation of individual terminal hinge axis positions in the sagittal plane, 118 stomatognathicly healthy patients were subjected to three occlusal registration methods. In these situations it is necessary to consider occlusal contacts relative to CR. Look out for an anterior thrust associated with a deflective RCP–ICP slide. Fig 8-6a Markings for left lateral excursion showing poorly defined guidance on the canine. Unfortunately, wax distorts easily, and so distorts the alginate it is supposed to be supporting. Electrical stimulation may be used in an attempt to condition the masticatory muscles prior to recording CR, together with electromyographic instrumentation to determine lack of muscle splinting. Indeed, some patients will experience “neuromuscular release”, whereby the mandible, previously affected by muscle splinting, suddenly becomes easy to manipulate. An interocclusal record is often necessary to achieve this, but not always. The third method measured OCA using occlusal registration at moderate and maximum occlusal force, and considering contact at the 2 interocclusal distances (0-100 and 0-200 µm). Fig 8-19 This mark, called the “third reference point”, aligns the facebow to the patient’s horizontal plane. The usual procedure is to measure the OVD and resting vertical dimension with a Willis gauge. The DVD shows a number of tips, including: drying the teeth and smearing material on the occlusal surfaces prior to seating the tray to avoid occlusal air blows (Fig 8-8), pulling unset material over the heel of the tray with a mouth mirror to help keep the impression in the tray on removal from the mouth, trimming the impression to allow inspection and reduce distortions prior to pouring up (Fig 8-9). A deflective contact or interference, however, can be eliminated before preparing the tooth, and so avoid reproducing it in the restoration. If finding the hinge axis is something you find difficult, then you are not alone. This also makes life easier when assessing the frontal and occlusal plane with a fox gauge. In essence, the occlusal examination allows important tooth contacts to be identified. The advantage is that mounting accuracy can be checked on the articulator using shim stock between both opposing copings and unprepared teeth. It is possible to identify isolated occlusal problems without systematically following the procedure shown in the video, but this requires intuition and experience. Fig 8-13b Casts with silver dies mounted. Riise C, Sheikholeslam A. Simple quality control at this stage can save a lot of subsequent grief. Excursive contacts, when marked with foil, should appear smooth and unbroken. These are useful teaching and research instruments, but they find limited application in clinical practice. There is little objective information regarding the use of the more recently introduced elastomeric materials which are growing in popularity in the clinic. Many dentists treat alginate as a humble and somewhat inaccurate material. Some articulator manufacturers supply devices to check the reproducibility of multiple CR registrations, for example the Denar Vericheck. Some facebows use a pointer specifically to align with the infraorbital notch. Occlusal rims Most commonly used material is medium baseplate wax ,modelling plastic may also be used. This principle applies whatever material is used. Occlusal height and horizontal occlusal position can be located by the aforementioned methods. Shim stock is a 10 μm-thick Mylar film and is held in mosquito forceps. Wax is occasionally used for sectional ICP records (Fig 8-12). Assuming that meticulous laboratory protocols can be used to create well-fitting esthetic restorations, the occlusion can make or break the clinical outcome. It is something you can practise on any patient. Therefore, this study aims to evaluate the accuracy of virtual occlusion by comparing virtual occlusal contact area with actual occlusal contact area using a plaster model in vitro. This usually does not produce any significant problems, but the rule to follow is to record the interocclusal registration at, or very close to, the vertical dimension required, thereby minimising the impact of any hinge axis discrepancy. In addition, the occlusal plane and fullness of the lips are established, and other orientation marks for the artificial teeth are traced. The occlusal registration is an important diagnostic source of information for dentists and orthodontists. In practice this will be for very few patients. A major requirement for this technique is to have one or more posterior or anterior occlusal stops that need to be verified even before anesthesia is administered. This clinical study compared two occlusal registration methods (Occlusal Indicator Wax and Accufilm) with the T-Scan system for the identification of guided closure contacts. Once you have mastered the technique, it becomes a matter of routine. Anatomically, this is the Frankfort plane, extending from the tragus of the ear to the infraorbital notch. In making assessments about whether and how such pivots may need to be managed, mounted casts usefully supplement the clinical occlusal examination. Nevertheless, posterior teeth are often involved in guiding jaw movements. A modified occlusal registration and implant transfer technique. Quantitatively, estimate how far the mandible deviates forwards or laterally by looking at the relationship between the upper and lower incisors during the slide. ; Watts, D.C.; Wilson, N.F.H. Usually, simple techniques for separating the teeth are sufficient to allow successful bimanual manipulation. Fig 8-20 The bitefork and black transfer jig are attached to an articulator. These tend to be patients who appear to have lost occlusal vertical dimension (OVD), either with excessive wear or tooth loss, and where an increase in OVD, and therefore an occlusal reorganisation, is planned. Fig 8-8 Reduce air bubbles by smearing alginate onto the occlusal surfaces. Evaluate the thickness and the marking quality of different occlusal contact registration strips (OCRS) and a possible correlation between them. Clinical indicators of active parafunction include fremitus, tooth tenderness and ridging of the sides of the tongue or cheeks at the level of the occlusal plane. The patient needs to relax, and so does the dentist. incorrect assumptions regarding the orientation of the occlusal plane. localised wear on palatal aspects of upper anterior teeth and fremitus – see below, Note the guidance teeth and interferences on the working and non-working sides, Note the guidance teeth: interferences are usually on the posterior teeth, Where indicated, measure occlusal and rest vertical dimensions, Also take into account facial profile, need for interocclusal space and aesthetic requirements. The influence of experimental interfering occlusal contacts on the postural activity of the anterior temporal and masseter muscles in young adults. For any given case, you might start with casts mounted in CR and plan treatment on this basis. Some find it helpful to use a structured record form, but, once you are familiar with carrying out an occlusal examination, the relevant findings can be recorded as shown in Table 8-1. Murray, M.C. But accuracy is paramount when articulating diagnostic casts and when preparing opposing casts for indirect restorations. Traditionally, self-cured acrylic is used as the registration material, but registration paste can be used. Figure 14.1 Clinical photograph showing wax block-outs of missing maxillary posterior teeth and a lower RPD in place. Problems with hand-held casts occur when they cannot be easily and reliably located in a stable intercuspal relationship. This Impact Dental Training expanded function course on Taking Occlusal Registrations has been approved by the Iowa Dental Board and meets course requirements for dental assistants and hygienists. Set up an examination tray (Fig 8-2) with thin articulating foils (< 20 μm thick) and shim stock. A full-arch record is almost never needed, perhaps only where there is an anterior open bite and the casts rock; but even then, trimmed localised records may be possible. Unlike alginate, silicone impressions can be re-poured without significant loss of accuracy. A simpler alternative is to record pairs of teeth that resist the removal of shim stock. Ease of handling is rarely a problem with modern materials since they are cartridge-delivered and have sufficient flow (i.e., consistency) to adequately and evenly spread over (i.e., wet) the teeth before starting to set. It has the advantage that you can readily re-manipulate the jaw to assess whether the teeth re-engage cleanly into the indentations (Fig 8-16). With the patient sitting upright, the normal range of freeway space is 2–4 mm. Where one is used, it should be as minimal as is required to locate the casts accurately. Articulator choice is covered in Section 8-6. The general principle is to limit, where possible, the ICP record to the preparations and the opposing teeth. On the one hand, a flat occlusal plane with a shallow angle to the horizontal plane – the patient’s Frankfort plane – will dispose to posterior disclusion. More unusual causes of deflective contacts and interferences include jaw fracture and tooth movements occurring during pregnancy (Fig 8-1). Analysis of two methods for occlusal contact registration with the T-Scan system J Oral Rehabil. The ability to find the hinge axis depends as much on your own demeanour as on the cooperation of the patient. The wax rims establish the vertical dimension and delineate the occlusal plane, the lip line, smile line and midline. tragus line in dentate subjects to provide a guideline for establishment of occlusal plane for edentulous patients methods in local dental college from april to october 2017 using purposive Aug 30, 2020 occlusal registration for edentulous patients dental technique series vol … Wax rims are, however, supported only by soft tissues, so when patients bite onto a wax rim the baseplate is displaced into the soft tissues. Rim-lock trays are a good alternative to perforated trays. These serve only to delay completion of the patient's prosthetic requirements. Bear in mind that a baseplate made on the cast from one impression cannot reliably be transferred to a cast poured from another – there are always differences between casts recorded by multiple impressions. Fig 8-11a Superfluous detail in a record, including embrasures and gingival tissues, can prevent it seating on the casts. The DVD shows how a silicone mousse record can be made. When taking impressions for study models in complex cases, this may prove to be cost effective. When restoring multiple anterior teeth, a facebow helps to define the occlusal plane and avoid having a “run” on the restorations. The answer to this is no, not for routine examinations. In simple terms, the jaws and TMJs comprise a lever system. This excrescence indents into registration material placed on the occlusal surface of the lower coping. If you do not use adhesive with a perforated tray or you give insufficient time for the adhesive solvent to evaporate, the risk of this distortion is greatly increased. The paste can be made to stick to the coping by first applying a coat of dental varnish. Is the contact likely to be removed during tooth preparation for restorations? To minimise this, trim away the occlusal indentations in the rim until there is firm contact on the teeth and only light contact on the rim, so that it is sitting passively on the mucosa. Occlusal registration: science or art? Being able to find the hinge axis and then record it is an essential skill in restorative dentistry. The disadvantages of rim-lock trays include ensuring their return from the laboratory and difficulties in cleaning prior to decontamination and sterilisation. The technique using wax rims fabricated on the master casts is still the gold standard to determine maxillo-mandibular relations and interocclusal registration in edentulous patients. Some operators draw a diagram of the pattern of occlusal contacts marked with articulating foil. Laboratory comparison of three occlusal registration methods for identification of induced interceptive contacts When a registration is used in the construction of definitive restorations at an increased vertical dimension, the mandibular position is best stabilised during the procedure by using one or more provisional restorations made at the desired dimension. Fig 8-10 Silicone ICP record used for a patient with an anterior open bite – a rare case in which a full-arch record is justified. Qualitatively, the slide will either be present or absent, smooth or rough, small or large. Screening for a history of a painful or clicking jaw, muscle and/or temporomandibular joint (TMJ) tenderness on examination, significant joint sounds (bearing in mind that mild clicking is very common) and limitation of jaw movement is appropriate for all patients. Nevertheless, some patients are difficult to manipulate. The correct bite is reached when : the teeth close "where they meet best" the bite is "heaviest" on the back teeth Excessive tooth wear is often compensated for by dentoalveolar extrusion. With these systems, an intraoral camera can be utilized for optical bite registration as well as optical impressions of the dentition. Forces applied to the teeth by the masticatory muscles diminish as you move anteriorly. Fig 8-16 Remove the record, chill under cold water, replace and check the teeth close cleanly into the indentations. They can, however, be invaluable for planning treatment, communicating with the laboratory and explaining treatment to the patient. In practice, facebows are accurate to millimetres while interocclusal records need to be accurate to micrometres. A written record of the existing intercuspal contacts can be helpful to the technician to ensure that casts are correctly mounted. Success with facebows is a matter of being vigilant. 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