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Gothic arch tracing / certified orthodontic courses


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Gothic arch tracing / certified orthodontic courses

  1. 1. INDIAN DENTAL ACADEMY Leader in continuing dental education
  2. 2. INTRODUCTION The method of recording the jaw relationships using base plates and occlusion rims, is widely carried out in clinical practice. However, as many dentures with an unstable occlusion are seen, it is thought that minor errors tend to occur easily using this technique. There are various reasons to explain this. If the clinician is not accustomed to the procedure of softening the wax, it will be difficult to soften the rims evenly. Without uniformly softened rims, an exact record cannot be expected. When the base plates poorly fit the alveolar ridges, they are displaced by sliding over the occlusal plane during recording and thus the jaw registration is carried out with displaced rims. In addition, as the mucosa of the alveolar ridge is compressible, some portions of the base plate settle into the mucosa slightly and another portion is raised up. In a case with severe ridge resorption, the base plate will be easily displaced. In a patient with a loose temporomandibular joint or wearing an existing denture with a malocclusion for a long time, the eccentric relation might be easily recorded by a little undue pressure.
  3. 3. In any case, it requires great skill for the horizontal and vertical jaw relations to be recorded simultaneously just by using the baseplates to establish an exact jaw relationship. The chair time will also be prolonged, and thus the physical fatigue of the patient will increase. To solve these problems, the author divides the procedure into two stages. The gothic arch tracer is used for recording the horizontal jaw relation. The patient must come to the clinic once more, but as the final decision can be left to the use of the gothic arch tracer, the procedure for recording the vertical relation using base plates can be performed stress- free and moreover the total chair time for the recording jaw relations is shortened.
  4. 4. HORIZONTAL PLANE BORDER MOVEMENTS A mandibular element to be understood before recording maxillomandibular relationships and making tooth arrangements for complete dentures is border positions. Border refers to the boundary of a surface and may imply the limiting line. Border position is defined as the most posterior position of the mandible at any specific vertical relation. The border positions are limited by nerves, bones, muscle, teeth when present and ligaments. The limiting is not a simple mechanical stoppage but a physiologic control through the neuromuscular system. The envelopes of motion of the mandible in the border positions has been recorded in three planes horizontal, frontal and sagittal and are usually described as three dimensional. Traditionally, a device known as a Gothic arch tracer has been used to record mandibular movement in the horizontal plane. It consists of a recording plate attached, to the maxillary teeth and a recording stylus attached to the mandibular teeth. As the mandible moves, the stylus generates a line on the recording plate that coincides with this movement. The border movement of the mandible in the horizontal plane can therefore be easily recorded and examined.
  5. 5. When mandibular movements are viewed in the horizontal plane, a rhomboid-shaped pattern can be seen that has a functional component, as well as four distinct movement components.  Left lateral border  Continued left lateral border with protrusion  Right lateral border  Continued right lateral border with protrusion Left Lateral Border Movements With the condyles in the CR position, contraction of the right inferior lateral pterygoid will cause the right condyle to move anteriorly and medially (also inferiorly). If the left inferior lateral pterygoid stays relaxed, the left condyle will remain situated in CR and the result will be a left lateral border movement (i.e., the right condyle orbiting around the frontal axis of the left condyle). Therefore the left condyle is called the rotating condyle, because the mandible is rotating around
  6. 6. The right condyle is called the orbiting condyle, because it is orbiting around the rotating condyle. The left condyle is also called the working condyle, because it is on the working side. Likewise, the right condyle is called the nonworking condyle, because it is located on the nonworking-side. During this movement the stylus will generate a line on the recording plate that coincides with the left border movement.
  7. 7. Continued Left Lateral Border Movements with Protrusion With the mandible in the left lateral border position, contraction of the left inferior lateral pterygoid muscle along with continued contraction of the right inferior lateral pterygoid muscle will cause the left condyle to move anteriorly and to the right. Because the right condyle is already in its maximal anterior position. The movement of the left condyle to its maximum anterior position will cause a shift in the mandibular midline back to coincide with the midline of the face.
  8. 8. Right Lateral Border Movements Once the left border movements have been recorded on the tracing, the mandible is returned to CR and the right lateral border movements are recorded. Contracting of the left inferior lateral pterygoid muscle will cause the left condyle to move anteriorly and medially (also inferiorly). If the right inferior lateral pterygoid muscle stays relaxed, the right condyle will remain situated in the CR position. The resultant mandibular movement will be a right lateral border movement (e.g., the left condyle orbiting around the frontal axis of the right condyle).
  9. 9. The right condyle in this movement is therefore called the rotating condyle, because the mandible is rotating around it. The left condyle during this movement is called the orbiting condyle, because it is orbiting around the rotating condyle. During this movement the stylus will generate a line on the recording plate that coincides with the right lateral border movement.
  10. 10. Continued Right Lateral Border Movements with Protrusion With the mandible in the rightWith the mandible in the right lateral border positionlateral border position contraction of the right inferiorcontraction of the right inferior lateral pterygoid muscle alonglateral pterygoid muscle along with continued contraction ofwith continued contraction of the left inferior lateral pterygoidthe left inferior lateral pterygoid will cause the right condyle towill cause the right condyle to move anteriorly and to the left.move anteriorly and to the left. BecauseBecause the left condyle isthe left condyle is already in its maximum anterioralready in its maximum anterior position, the movement of theposition, the movement of the right condyle to its maximumright condyle to its maximum anterior position will cause aanterior position will cause a shift back in the mandibularshift back in the mandibular midline to coincide with themidline to coincide with the midline of the face. Thismidline of the face. This completes the mandibularcompletes the mandibular border movement in theborder movement in the horizontal planehorizontal plane..
  11. 11. Lateral movements can be generated by varying levels of mandibular opening. The border movements generated with each increasing degree of opening will result in increasingly smaller tracings until, at the maximally open position, little or no lateral movement can be made. Mandibular movements in the horizontal plane:- 1)Left lateral 2)Continued left lateral with protrusion 3)Right lateral 4)Continued right lateral with protrusion. CR– centric relation ICP –intercuspal
  12. 12. Horizontal relations are those that are established anteroposteriorly and mediolaterally and so are classified as : Centric Relations Eccentric Relations Protrusive Relations Lateral right lateral left lateral
  13. 13. CENTRIC RELATION is defined as the maxillomandibular relationship in which the condyles articulate with the thinnest avascular portion of their respective discs with the complex in the anterior –superior position against the slopes of the articular eminences. Features and Significance Of Centric Relation Centric relation is the ideal arch to arch relationship and an optimum functional position of the jaws for the health, comfort and function of the musculature. It is a mandibular position where the condyle disc assembly is seated in anterior superior position against the posterior slope of articular eminence, which was believed by many to be the rearmost, upmost, midmost position in the glenoid fossa. (RUM position). Centric relation of the mandible is a hinge position. In Centric relation condyles exhibit only pure rotation without translation.
  14. 14. Mandibular movements return or terminate in centric. It is thus a reproducible position and therefore serves as a reliable reference to develop centric occlusion in artificial dentures. It is a starting point for the arrangement of artificial teeth in articulator to develop maximum intercuspation in complete dentures. It is a position where upper and lower teeth are braced against each other during deglutition. It serves as a reference position for the occlusal reconstruction in dentulous situations. It is the posterior border position and the posterior limit of the envelope of mandibular motion. To summarize Centric relation is a reproducible, recordable, consistent reference position, and a physiologically acceptable position for deglutition.
  15. 15. Recording Centric Relation in Edentulous Subjects In edentulous subjects, centric jaw relation is generally recorded by Wax closure method Functional chew in technique Graphic method Anterior deprogrammers Wax closure method of recording centric relation with swallowing, phonetics and manual guidance is quick and a simple method. The arrow point tracing method is a reliable and scientific procedure of recording the mandibular border movements in the horizontal plane and captures the mandible at its posterior reproducible border position.
  16. 16. Limitations of Wax Occlusal Rim Method to Record Centric Relation Inconsistency of the record: two centric records taken for the same patient may not always be identical. Patient co-operation and operator-induced errors should be considered. Possibility of occlusal rims sliding over the other to any eccentric position either before , during or after sealing the occlusal rims in centric relation. Tilting, leverage and displacement of record bases is very common and this may result in inaccurate centric record. There is a tendency for the patient to bite and protrude the mandible. The term bite registration is therefore objectionable and obsolete.
  17. 17. ECCENTRIC RELATIONS Is defined as any relationship of the mandible to the maxilla other than centric relation. The eccentric relations that are recorded and used in complete denture construction are protrusive and right and left lateral. Protrusive relation is the relation of the mandible to the maxilla when the mandible is thrust forward. If the motion in every part of the mandible as it is thrust forward has simultaneously the same velocity and direction, the motion could be correctly termed translatory. The movement in the joint is downward and forward. The condyles disk assemblies are guided downward by the articular eminences of the glenoid fossae. The angle of slide varies from patient to patient and from side to side. The muscles responsible for a straight protrusive movement are the inferior pterygoid muscles acting simultaneously. Protrusive relation is a bone-to- bone relation, which can be recorded.
  18. 18. Right and left lateral maxillomandibular relations are the relations of the mandible to the maxillae when the mandible is moved either to the right or to the left side. The movement of the mandible is the result of the contraction of contra lateral inferior external pterygoid muscle. When the external pterygoid of one side contracts, the corresponding side of the mandible is pulled forward and inward, while the other side remains comparatively fixed. The side that is pulled forward is termed the nonworking, balancing, or orbiting side, whereas the side that remains comparatively fixed is termed the working, or rotating side. The movements in the non-working side are downward, forward, and inward. The movement is both sliding and rotary. The movements in the working side are rotational.
  19. 19. The question of necessity for eccentric records is controversial, because accuracy is a problem in the recording methods and the capabilities of the articulator to receive and reproduce the record. The following factors contribute to inaccuracy: (1) Instability of records, (2) Resiliency and displaceability of denture-bearing tissues, (3) Materials used in record making, (4) Equipment used in record making, (5) Lack of muscle coordination in the patient, and (6) The use of articulators that do not accurately adjust to all lateral interocclusal check records.
  20. 20. The controversy about the merits of eccentric records will exist as long as there are differences in the concepts of occlusion and posterior tooth form required for complete dentures. Prosthodontists who prefer a cusp form posterior tooth and balanced occlusion in eccentric jaw positions or organic occlusion will require eccentric maxillomandibular relation records. Prosthodontists who prefer a noncusp form posterior tooth and balanced occlusion in centric jaw position will not require eccentric maxillomandibular relation records.
  21. 21. GRAPHIC METHOD The graphic methods record a tracing of mandibular movements in one plane, an arrow point tracing. It indicates the horizontal relation of the mandible to the maxilla. The apex of a properly made tracing presumably indicates the most retruded relation of the mandible to the maxilla from which lateral movements can take place. Graphic records are either intra oral or extraoral, depending on the placement of the recording device. Even though Balkwill, and Englishman, in 1866 illustrated the right and left intersection arcs of lateral movement, it was Hesse from Germany, in 1897 introduced the graphic method of recording centric relation, which was later popularized by the Swiss professor Gysi in 1910. It became known as Gysi gothic arch tracing since it resembled Gothic architecture characterized by high pointed arches.
  22. 22. The Glossary of Prosthodontic terms recommends Central Bearing Tracing, Gothic Arch Tracing, Needle-point Tracing as the pattern obtained on the horizontal plate used with a central bearing tracing device. Central bearing tracing device is a device that provides a central point of bearing or support between maxillary and mandibular dental arches. It consists of a contacting point that is attached to one dental arch and a plate attached to the opposing dental arch. The plate provides the surface on which the bearing point rests or moves and on which the tracing of the mandibular movement is recorded. It may be used to distribute the occlusal forces evenly during the recording of the maxillomandibular relationships and /or for the correction of disharmonious contacts. All movements in the horizontal plane initiate from the apex of the Gothic arch. The apex of tracing is a reproducible reference point, which represents centric relation. Gothic arch tracing ensures that the centric record is made with minimal closing force equally distributed over the supporting tissues.
  23. 23. HISTORY The earliest graphic recordings were based on studies of mandibular movements by Balkwill in 1866. The first known “needle point tracing” was by Hesse in 1897 and the technique was proved and popularized by Gysi around 1910. Clapp in 1914 described the use of a Gysi-tracer, which was attached directly to the impression trays. In 1926 Sears used lubricated rims for easier movement and placed the needlepoint tracer on the mandibular rim and the plate on the maxillary rim. He believed this made the angle of the tracing more acute. Philips in 1927 recognized that any lateral movement of the jaws would cause interference of the rims, which could result in the distorted record. He developed a plate for the upper rim and a tripoded balls bearing mounted on a jackscrew for the lower rim. This was named the “central bearing point”, which produced equalization of pressure on the edentulous ridges.
  24. 24. In 1929, Stansbery introduced a technique, which incorporated a curved plate with a 4" radius mounted on the upper rim and central bearing screw of 3" radius on the lower rim. Plaster was injected after tracing was made. HalI in 1929 use the Stansbery technique but he used compound as record. Later graphic recording methods were developed which used the central bearing point to produce the gothic arch tracing . Hardy 1942 and Pleasure 1955 described the use of the Coble balancer The patient would hold the bearing point in the depression while plaster was injected for the centric record. Pleasure1955 used a plastic disk, which was attached to the tracing plate with a hole over the apex of the Gothic arch. The centric relation record could then be made without a change of vertical dimension and Hardy later designed a modified intra oral trace similar to the Coble.
  25. 25. The Sears Recording Trivet had an intraoral central bearing point and two extraoral tracing plates. Robinson designed the equilibrator in 1952 , a tracing device with a hydraulic system and 4 bearing pistons, one each in the bicuspid and molar region. It produced a functional record of centric relation with a uniform distribution of stress over the basal seat. Silverman 1957 used an intraoral Gothic arch tracer to locate the "biting point" of a patient. The patient was told to bite hard on the tracing plate. This developed the functional resultant of the closing muscles, which would retrude the mandible. The indentation made by the patient would be used for the centric record whether or not it corresponded to the Gothic arch apex. Another change in the graphic method was using the central bearing as a tracer to register intra oral gothic by Blanchad, Musseinan, Copie, Wastrow.
  26. 26. Hardy introduced a central bearing device with 2 heads. One end was brass pointed and used in recording the tracing; the other end consisted of a mounted steel ball bearing, which was used as an anatomical teeth set to a flat plane of occlusion. Height, Sears, House and many others who had devised tracing procedures of their own which enabled them to secure dependable centric relation. To make a needlepoint tracing one condyle moves forward and inward during a lateral movement followed by a movement in opposite direction with rotation occurring around the opposite condyle, these movement cut lines extending to the point representing the most retruded position of both condyles. Therefore when both condyles are resting in the most retruded position the needlepoint of the tracing will be resting at the apex of the tracing thus created. A needlepoint tracing is fundamentally a single representation of the portion of the mandible and its movements in a horizontal plane.
  27. 27. Limitations Of Graphic Method Gothic arch tracing method is preferred in good edentulous ridges with normal interarch relation. Arrow point tracing is difficult in excessively resorbed and flabby ridges as it causes instability of the recording bases and this restricts its use. Graphic method is not indicated when there is inadequate inter arch distance, as it is difficult to accommodate the tracing device without increasing the vertical dimension. A sharp arrow point cannot be traced in persons with TMJ arthropathy. In these instances conventional wax closure method is the alternative choice. Intra oral gothic tracing method is ideal in patients with habitual centric. A few complete denture patients develop habitual centric either due to faulty centric relation, or due to prolonged use of very old denture with marked attrition which causes a forward habitual positioning of the lower jaw.
  28. 28. This is a case of "habitual eccentric occlusion". When the patient has worn inappropriate dentures for a long time, the occlusion is habitually out of the centric occlusal position due to the functional adaptation of the body in which one masticates in a position comfortable to him/herself. In these patients it is difficult to record centric relation with wax closures as they tend to move the jaw to habitual centric relation position, which is anterior to the actual centric. The Gothic arch method is indicated in these patients. With intra oral gothic arch tracing method, the stylus eliminates occlusal contact from occlusal rims and therefore the habitual neuromuscular memory or engram is absent. The likelihood of sliding the lower jaw forward and laterally is hence eliminated.
  29. 29. PARTS OF THE GOTHIC ARCH TRACER The device used is called a gothic arch tracer which essentially consists of ­ 1 A marking or recording and a tracing or recording table attached to the upper or lower arches. 2.Stabilized base plates to prevent lateral movement and rocking thus ensuring minimum errors in recording. 3 A central bearing device/screw to provide a central point of bearing or support between the maxillary and mandibular occlusal rims. It consists of a contracting point which is attached to one occlusal rim and a plate attached to the other occlusal rims which provide the surface on which the bearing point rests or moves without any change in the vertical dimension. The device is placed at the central bearing point, which is located as the center of the supporting areas of the maxillary and mandibular jaws.
  30. 30. Hight extra oral tracer assembly Sears extra oral tracer assembly Swissdent ball bearing bite recorder Microtracer for intra oral use
  31. 31. It is used for the purpose of distributing closing forces, evenly throughout the areas of the supporting structures during recording of maxillomandibular relations. The central bearing helps to maintain the unstrained relation of the base plates to the supporting mucosa, with an almost ideal distribution of contact pressure. Means of locking the tracer at the apex of the needle point tracing:­ 1) a hole or a depression into which the needle point would fall. 2) a plastic/ metal disk with a hole which was placed over the apex of the tracing. This served as a convience and as a guide for the patient to hold a centric position while the registration was secured.
  32. 32. Positioning Of The Central Tracing Point It is important to direct the force uniformly to the basal structures and thereby ensuring stability of the base plates and uniform vertical contact. The central bearing point can be placed at the midline of the upper arch at the point where it is intersected by a line joining the distal surfaces of the second premolars. Stansberry has suggested placing the central bearing point at the point of intersection of the lines drawn from the cuspid on the side to the second molar on the other side. Positioning the tracer (H.Villa) The tracer is locted in a vertical position in some procedures, while in others it is at variable inclinations. To obtain correct gothic arch tracing stabilized base plates and central bearing point must be used and it must be perpendicular to condylar hinge axis of mandible.
  33. 33. EXTRA ORAL TRACINGS AND DEVICES A Gothic arch tracing, as the name implies, is a pin­point tracing on soot or carding wax that is shaped after a type of architecture known as the Gothic arch. It sometimes is referred to as the arrow point tracing. When one condyle moves out in lateral, the movement approximately rotates around the other condyle. This movement cuts a line starting from a point, which is the most retruded position of the rotating condyle. When the opposite condyle is caused to move on its path, it starts from the same point and cuts a line at an angle to the other line. Therefore, when both condyles are resting in their most retruded positions, the needlepoint of the tracer will be resting on the apex of the Gothic arch thus created. A Gothic arch tracing is fundamentally a single representation of the position of the mandible and its movement on one plane. This statement should be modified if several pins are used, such as the Sears trivet and further modified if the tracing is of the type suggested by Phillips. The Phillips tracer indicates the condyle path as well as the direction and centric position of the mandible.
  34. 34. Techniques Of Graphic Tracings Gysi suggested 3 main point of movement of mandible namely, the 2 condyles and the incisal point. If a recording device is used to record the incisor point as the mandible is moved laterally a V ­shaped tracing is obtained. This is called by Gysi as the gothic arch. The apex of which is most retruded position of the mandible from which lateral movements are made. Different technique were designed since 1910. EXTRA ORAL: Gysi tribyte ­ This technique omits the use of central bearing plates which necessitates special care in establishing the contacting areas of the two bite plates. Failure to produce equal contact over the entire occlusal area of the opposing bite planes in centric relation introduces tilting forces on the bases.
  35. 35. Gysi technique In the original Gysi technique the occlusal plane is determined by locating the correct height of the upper occlusion rim. Then the lower occlusion rim is adapted to the upper rim at the correct vertical dimension of occlusion. The Gothic arch tracer is fixed to the upper rim at the occlusion rims with the tracing table paralell to, or continous with, the plane of occlusion. The central bearing point is not used. No mention is made of the inclination of the tracing point. No cusp height is introduced. This means that even contact of the occlusion rims is lost when the patient makes forward or lateral excursions of the mandible because of the forward and downward movement of the condyles.
  36. 36. The Sears trivet is a central bearing point tracer with two registration pins. The pins are attached to the mandibular plate therefore they will give a reverse gothic arch as compared to those with the pin attached to the maxillary plate. It traces 2 gothic arches simultaneously. It has the facility of making the records extra orally with plaster of paris.
  37. 37. A Boos Bio-meter with tracing table and marker is another extra oral method for obtaining gothic arch tracing. The bio­meter provides an indication of the position of the mandibular by tracing and records the forces of closing. (The V.R. is adjusted using bio­meter).
  38. 38. Stansberry cheek bite method - Stansberry developed and popularized the use of central bearing point in connection with the tracing device for recording positional relations of the jaw. With the Stanberry’s cheek bite appliance records can be made of centric jaw relations and protrusive relations. The tracing device is removable from its attachment locations on the maxillary and mandibular bearing plates. The Phillips Graphic record registers the centric relation and the condylar paths. Phillips tracer is another type of tracing device that registers centric relation and the condyle path simultaneously.
  39. 39. The technique for an arrow point tracing using a Hight tracing device Make accurate, stable maxillary and mandibular record bases. Attach occlusal rims of hard base plate wax Contour the wax occlusion rims Establish the vertical dimension of jaw separation with the mandible at physiologic rest. Reduce the mandibular occlusion rim to provide excessive interocclusal distance
  40. 40. Make a face bow transfer and mount the maxillary cast With the soft wax make a tentative centric relation record at a predetermined vertical dimension of occlusion. Adjust the articulator with the condylar elements secured against the centric stops Relate the maxillary occlusion rims of the soft wax record and attach the mandibular cast to the articulator with plaster. Mount a central bearing device. Exercise care to center the central bearing point in relation to the plate, both anteroposteriorly and laterally. Mount the tracing device. Be sure to attach the devices securely to the occlusion rims. The stylus is attached to the maxillary rim and the recording plate to the mandibular. This arrangement develops an arrow point tracing with the apex anteriorly. The reverse develops an arrow point tracing with the apex posteriorly.
  41. 41. Seat the patient with the head upright, in a comfortable position in the dental chair Place the record bases in the patient’s mouth with the attached recording devices. Inspect the record bases and the recording devices for stability. Make sure that there is no interference between the occlusion rim when the mandible is moved in any direction. Lower the stylus to the recording plate and determine that the stylus maintains contact with the recording plate during mandibular movements. Retract the stylus and conduct the training exercises with the patient. Place the tips of the index fingers under the mandible in the bicuspid areas. Place the tip of the thumb under the mandible near the chin. Calmly and quietly instruct the patient to move the jaw forward, backward and to the right and left while gently applying guiding pressure with the thumb. It is possible to dislodge the mandibular record base by improperly placing the thumbs or by exerting excessive pressure. The Ney Excursion Guide is an aid in training the patient.
  42. 42. When the patient is proficient in executing the mandibular movements, prepare the tracing plate to record the tracing. A thin coating of precipitated chalk in denatured alcohol applied evenly with a brush provides a medium that offers no resistance to the movement of the stylus and produces a clearly visible tracing. Develop an acceptable tracing by dropping the stylus to the record plate. When a definite arrow point tracing with a sharp apex is made, have the patient retrude the mandible to centric relation. The point of the stylus should be at the point of the apex of the arrow point tracing. Inject quick setting dental plaster between the occlusion rims and allow the plaster to harden. Remove the assembly and mount with the mandibular cast with the new record. This record is a tentative record and will be checked with an interocclusal check record when the teeth are arranged and the wax is contoured.
  43. 43. The appliance used consists of two bearing plates to which a stylus holder and graph plate may be attached. A template for proper spacing of the bearing plates and a glass syringe to aid in placing plaster.  Technique  1)The occlusal rims adjusted to the correct vertical relation  2)They are mounted on an articulator with the screw tightened to maintain the relation of the casts. STANSBERRY FUNCTIONAL POSITION CHECK BITE METHOD
  44. 44. 2)The central bearing plates are placed in the template which has been placed on the bite plates that had been shortened to provide space for it. 3)With the central bearing plates attached to the bite plates, the central bearing screw is brought into contact and the tracing table and the stylus are attached. 4)A gothic arch tracing is developed by the patient. This relation is maintained and the plaster is injected when the plaster is injected. When the plaster has set the record is marked and set aside for later use. 5)Accommodation for cusp height in lateral movements is accomplished by raising the screw in the bearing plate by one and 1/2 turn. A second 9 inch is developed due to the increased vertical dimension. From the apex of this tracing a mark 1/4 inch or 6mm distant is made on each lateral path. This marks the position of the needle point for lateral records. 6)The central bearing point is raised one half turn more for the protrusive registration.
  45. 45. Classification Of Arrow Point Tracing Gerber described six different types of Gothic arch tracings. Typical – seen as a well­defined apex with a symmetrical left and right lateral component. The mean Gothic arch angle is about 120 degrees. It reflects a healthy TMJ without interferences in condylar path and a balanced muscle guidance. The symmetrical form indicates an undisturbed movement of the condyle in fossa and distal slope of eminence with symmetrically balanced muscle guidance. Flat form – it is similar to typical arrow point except that it has more obtuse left and right lateral tracings. This type of arrow point signifies a marked lateral movement of condyle in the fossa. The Gothic arch angle is more than 120 degrees. Asymmetrical form – the left and right tracings meet in an arrow point, however their inclination to the protrusive path is not symmetrical one of the lateral tracing is shorter. This form of tracing indicates an inhibition of the forward movement, either in the left or right joint.
  46. 46. Apex absent /round form – instead of a sharp arrow point, the tracing is rather round. It shows a weak retrusive movement. Tracing should be repeated till a definite arrow point is obtained. Patient training is necessary. Miniature arrow point – similar to the typical arrow point, however the extension of tracing is very limited. This can be due to restricted mandibular movements, improper seating of record bases and painfully fitting record bases during registration. It is also an indication of a long period of edentulous ness with an inhibition in condylar movements. Double arrow point – it is a record of habitual and retruded centric relation. Allow patient training and repeat till a single gothic arch is obtained. It is also seen when vertical dimension is altered during registration.
  47. 47. Dorsally extended arrow point – the protrusive path extends beyond the apex of the gothic arch. This signifies a forced strained retrusive movement of the lower jaw either by the patient or the operator. During registration procedure lower jaw is either forcibly retruded by patient (active retrusion) or forcibly retruded manually by the operator (passive retrusion). It is sometimes an artifact caused by the forward displacement of upper occlusal rim or backward dislodgement of the lower rim while moving them in the mouth. The arrow point tracing is correct but at a particular stage there was sliding of upper occlusal rim forward and lower displacing backward. It can occur when the head of the patient is tilted too far posteriorly. Gerber felt that occasionally the distal extension is correct, but the tracing was obtained with the mandible in protruded position. Interrupted Gothic arch – break or loss of continuity of lateral incisal path of gothic arch. This happens due to posterior interference at heels of occlusal rims during lateral movements. Atypical form – protrusive component does not meet at apex but on one of the lateral path. This may happen in dentulous because of faulty muscular pattern due to parafunctional habits like bruxism. Also seen in very old edentulous patients, who are using complete dentures with incorrect centric relation.
  48. 48. Classical, pointed form The symmetry indicates an undisturbed movement sequence in the joints and uniform muscle guidance. EVALUATION OF GOTHIC ARCH TRACING Classical flat form The picture indicates distinct lateral movements of the condyles in the fossae. Weak Gothic arch tracing The picture indicates a lax and negligent performance of the movements, most of all of the backward components. The registration must be repeated. Stronger movements must be demanded from the patient.
  49. 49. Assymmetrical form The tracing indicates a distinct inhibition of the forward movement in the right joint. Miniature Gothic arch tracing The tracing points to cramp­like movements, badly fitting and pain­causing record blocks, edentulous state of long standing with inhibited movement in the joints, badly constructed prosthetic appliances, etc. Vertical line protrudes beyond the arrow point This tracing was produced either by forcible retraction or pushing of the mandible. It is, however, possible that the Gothic arch was obtained with a protruded mandible.
  50. 50.
  51. 51.
  52. 52. Vincent R Trapozzano (1955) When making a tracing for establishing centric relation on a patient with a normal temporomandibular joint, the apex of the initial tracing will be mounted frequently instead of having a definite apex. Aside from the technical factors the rounded apex may result from the patient’s failure to understand what is required when the right and left lateral movements are made, habit or a slight filling in of tissues behind one or both of the condyles. With some persistence on the part of the patient and operator, the patient may produce a needle point tracing with a definite apex. Sedation may be indicated to relax the patient. Suppose the blunted apex of the needle point tracing had been accepted as the position of centric relation, and that occlusal reconstruction, correction of occlusal disharmony of natural teeth, or denture reconstruction had been completed.
  53. 53. a definite malocclusion would result whenever the patient decided to close in the more retruded position (at the apex). In complete denture construction , the resulting area of malocclusion would produce an inevitable shifting and sliding of the denture bases, which would result in instability of the dentures and all of its undesirable sequalae. Since it is recognized that the individual will undoubtedly make many initial tooth contacts which vary from the most retrusive position (at the apex) to a slightly anterior (eccentric) position (on the blunted apex), provision must be made to avoid “grooving” the patient to the most retruded position before inclined plane contact is made. If the cusp teeth are used, this is accomplished by allowing for “free play”, a slight widening of the central grooves or fossa of the posterior teeth is made to provide an area larger than the size of the cusp which fits into the groove or fossa when initial tooth contact is made. Thus, provision is made for a limited range of horizontal movement of the mandible without engaging the inclined planes of the teeth.
  54. 54. Howard F. Smith (1975) A class III jaw relationship classically exhibits little anteroposterior movement, while a class II exhibits much. One may suggest little importance for anteroposterior precision, while the other may suggest great importance. An arthritic patient may exhibit limited movement in either direction.
  55. 55. Significance Of Gothic Arch Tracing It is important not to accept any other part of the tracing except the very apex as an indication of centric relation. When the patient chews lightly, they may often close their jaws in eccentric positions. However, patients will pull the mandible to complete retrusion many times under heavy closing pressure exerted during function of mastication. Therefore if the dentures are not constructed with centric occlusion in harmony with centric relation, the teeth will not contact evenly when under considerable closing pressure. This uneven or premature contacting is a disturbing factor in the retention and stability of dentures, and it can cause soreness of the tissues supporting the dentures. On the other hand, if centric occlusion is in harmony with centric relation, the patient can function properly with his mandible in all positions under light and heavy chewing pressures.
  56. 56. Extra oral tracings made without a central bearing point are not considered satisfactory because although they indicate the correct anteroposterior position of the mandible, they may not record the correct maxillomandibular relation (superioinferior relation of the jaw). It is extremely difficult to maintain equalized pressure on the blocks of wax. Therefore there is not much to be gained by securing a tracing without using a central bearing point.
  57. 57. SIGNIFICANT POINTS IN MAKING A GOTHIC ARCH TRACING 1. Displacement of the record bases may result from pressure, if the central bearing point is off center when the mandible moves into eccentric relation to the mouth. 2. If a central bearing device is not used the occlusal rims offer more resistance to horizontal movements. 3. It is difficult to locate the center of the arches to centralize the forces with a central bearing device when the jaws are in favorable relation and far more difficult if the jaws are in excessive protrusive or retrusive relation 4. It is difficult to stabilize a record base against horizontal forces on tissues that are pendulous or other wise easily displaceable. 5. It is difficult to stabilize a record base against horizontal forces on residual ridges that have no vertical height. 6. It is difficult to stabilize a record base or bearing device with patients who have large tongues.
  58. 58. 7. Recording devices are not considered compatible with normal physiologic stimulation in mandibular movements. 8 The tracing is not acceptable unless a pointed apex is developed, a blunt apex usually indicates an acquired functional relationship. 9. Double tracing usually indicates lack of coordinated movements or recording at the different vertical dimension of jaw separation. In either events additional tracing should be made. 10. A graphic tracing to determine centric relation is made at a predetermined vertical dimension of occlusion. This harmonizes centric relation with centric occlusion and the antero-posterior bone, to bone relation with the tooth - tooth contact. 11. Graphic methods can record eccentric relation of the mandibular to the maxillary. 12. Graphic methods can be considered the most accurate visual means of making a centric relation record with mechanical instrument, however all graphic tracings are not accurate.
  59. 59. INTRA ORAL TRACING DEVICE Intra oral tracings combine a central bearing point with a pinpoint tracing. The bearing point is pointed and records a tracing on the opposing plate. A hole is drilled in the plate at the apex of the Gothic arch in some techniques that employ intra oral tracing devices. This hole or depression is used to hold the patient in this retruded position while the registration is being recorded with plaster or some such material. The Seidel, Ballard and the Messerman tracers are examples of intraoral tracing devices. Another type of intraoral registration is afforded by the Needles technique in which three pins attached to the maxillary rim, one in the anterior portion and one on either side in the posterior region, register the movements of the mandible by means of three Gothic arches. They indicate both the centric position and the condylar paths .
  60. 60. Needles method Make accurate record bases with occlusal rims. Three pieces of wire are now imbedded in the rim of the upper base plate. One end of the wire is heated and forced into the modeling compound in the incisal region and the soft compound is packed firmly about the base of the wire. A wire is similarly placed on each side about the position of the distal side of the first molar. The wires are then cut off about 1.5 mm. above the surface of the bite rim. The incisal wire should strike the lower bite rim near the anterior border with the plates in centric occlusion, and the molar wires should strike slightly outside the middle of the lower bite rim, so that the tracing will not run off the edge of the lower bite rim. Each of these wires acts as a stylus to trace the paths of the respective points upon the surface of the lower bite rim. The insides of the bite plates are dusted with powdered gum tragacanth to help maintain them firmly on the ridges. They are then placed in the patient's mouth and the patient is requested to close until one or more of the pins come into light contact with the lower bite
  61. 61. The patient is then asked to move the mandible forward and back in the median line, maintaining a light pressure on the bite rims, the pins come into equal bearing and each cuts a record of its path in the lower bite rim, which gives the path of straight protrusion. Before these paths are cut too deep, the patient is requested to retrude the mandible to its fullest extent and slide it to one side and back again, slight contact of the pins being maintained. This movement is repeated a few times and then the same is performed on the opposite side. Thus the three paths are deepened evenly, thoroughly cut to the full depth of the respective pins; in this way a balanced three point contact has been maintained and the path of each point has been recorded for protrusion and for working bite on each side, while any separation that has taken place between the bite rims at any point during these movements has been recorded by a shallower tracing at that point. The form of the tracings will be found the same as Gysi's three-point tracing. The depth of the tracings also gives a record of the vertical relations. When the three pins are in the anterior angles of their respective tracings, the bite plates are accurately held in centric occlusion without the need of guide lines.
  62. 62. The Needles technique modified by the use of a Messerman central- bearing point tracer is suggested by Frahm. In this procedure the occlusion rims are constructed in exactly the same manner as was described by Needles. Four pins are, attached in the first bicuspid and second molar region on the right and left sides of the maxillary occlusion rims. By placing the pins in this position we are enabled to cut away the anterior portion of the maxillary occlusion rim to provide a window for observing the tracing appliance. The stylus portion of the tracer is attached to the vault of the maxillary trial base by imbedding the tripod prongs into Compound or wax. The graph plate is attached to the mandibular rim flush with the occluding surface of the rim. The two units should be mounted in a manner, which will permit the point of the maxillary appliance to rest near the center of the mandibular graph plate.
  63. 63. The relationship plates are returned to the mouth, and the screw on the maxillary appliance is adjusted so that it makes contact with the graph plate simultaneously with the contact of the maxillary occlusion rim pins on the mandibular occlusion rim. The patient then is instructed to make lateral and protrusive movements. As the pins scribe the Gothic arches on the mandibular rim, the vertical dimension is diminished a little at a time by means of the setscrew on the maxillary appliance. This is continued until the surfaces of the occlusion rim make
  64. 64. COBLE INTRA ORAL TRACING DEVICE Coble Balancer is a type of intraoral central bearing device. The central bearing point is attached with modeling compound to the upper Base plate in the center of the palate at the intersection of the midline and a line joining the centers of left and right chewing areas.
  65. 65. When placed in the mouth, the upper and lower base plates makeWhen placed in the mouth, the upper and lower base plates make contact only through the central bearing point at or very near the centercontact only through the central bearing point at or very near the center of the supporting areas of the upper and lower ridges.of the supporting areas of the upper and lower ridges. The central bearing screw is raised or lowered to establish the verticalThe central bearing screw is raised or lowered to establish the vertical dimension that provides an adequate free way space and the clearancedimension that provides an adequate free way space and the clearance between the base plates at the distal borders is checked.between the base plates at the distal borders is checked. At the chosen vertical dimension, the central bearing point, acting as aAt the chosen vertical dimension, the central bearing point, acting as a stylus, quickly draws a Gothic arch tracing as the patient performsstylus, quickly draws a Gothic arch tracing as the patient performs excursive gliding jaw movements. To lock the patients jaw in centricexcursive gliding jaw movements. To lock the patients jaw in centric relation at the apex of the Gothic arch tracing without changing therelation at the apex of the Gothic arch tracing without changing the vertical dimension, use a thin sheet about 1mm of clear Lucite as anvertical dimension, use a thin sheet about 1mm of clear Lucite as an overlay, and drill a small hole through it down to, but not into, theoverlay, and drill a small hole through it down to, but not into, the aluminum graph plate. The patient is then asked to perform a glidingaluminum graph plate. The patient is then asked to perform a gliding jaw movement and to stop when the central bearing point drops intojaw movement and to stop when the central bearing point drops into the hole which was drilled over the apex of the tracing.the hole which was drilled over the apex of the tracing. At the time of insertion of the processed dentures, the Coble Balancer is used again to integrate the gliding movements of the
  66. 66. with the occlusion of the teeth, to perfect occlusal balance, and to eliminate cuspal prematurities and collisions. At first the central bearing screw is adjusted to keep all teeth out of contact in all gliding movements. With the sole point of contact between the upper and the lower dentures located where the central bearing point touches the graph plate, the patient can perform jaw movements that are uninhibited by occlusal interferences. And a Gothic arch tracing is quickly scribed. The central bearing screw is shortened by half turn (0.5mm) at a time until a tooth to tooth contact occurs somewhere on the arch during the excursive gliding movements. Usually the first contact occurs on one or both second molars or on the canines. Sometimes it occurs between the denture bases behind the second molars if the interridge space is small. These occlusal contacts occur while the remaining teeth are still held out of contact by the central bearing point. They are treated as functional prematurities, and are ground down until they no longer interfere. The central bearing point is then shortened by one-fourth turn, and articulating paper is reinserted to mark the contact areas during the jaw excursions.
  67. 67. All the prematurities are thus located, marked and reduced until the majority of the teeth make contact during the gliding movements, with the central bearing point still riding on the graph plate. HARDY and PORTER Hardy introduced a central bearing device with 2 heads. One end was brass pointed and used in recording the tracing. The other end consisted of a mounted steel ball bearing which was used as an anatomic teeth set to a flat plane of occlusion. made a depression on the tracing plate with a round bur at the apex of the tracing. The patient would hold the bearing point in the depression while plaster was injected for centric record. PLEASURE improved this technique by using a hole which was attached to the tracing plate after the tracing was made, with the hole coinciding over the apex of the Gothic arch tracing. The central bearing point was held in a hole when a plaster was injected the centric would then be made without a change of vertical dimension.
  68. 68. Ballard intra oral tracing device Metal points attached to the upper modeling compound rim will cut pathways in the occlusal surface of the lower modeling compound rim as the patient moves the mandible from side to side. 1. Palatal bearing plate 2. Rounded head of correlator pin 3. Tension spring 4. Adjustable screw 5. Mounting plate 6. Pointed end of correlator pin
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  75. 75. ADVANTAGES AND DISADVANTAGES The intra oral tracing device has less assembly. Hence it is more comfortable for the patient. Also it makes the procedure of assembling the device and recording procedure easier for the operator. Since the intra oral tracing are small, it is difficult to find the apex compared to the extra oral tracing. The tracers must be definitely seated in the hole made by a round bur to assure accuracy when plaster is injected between the rims. Any shift in the position of the stylus from the position of the apex of the tracing cannot be prevented or corrected when plaster is being injected. Since any shift made is not seen and the procedure has to be repeated. The intra oral tracings cannot be observed properly during the tracing procedure and hence the method loses some of its value.
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  77. 77. R.H. Kingery (1952)reviewed the problems associated with centric relation which were PROBLEMS OF REQUIREMENTS Recording the correct anteroposterior or horizontal realtionship of the mandible to the maxilla in a position. Equalization of contact on the denture supporting areas – Equalization of vertical contact PROBLEMS OF ERRORS Positional Errors caused by Failure of the operator in his registration of the correct horizontal relationship. Failure of the operator to record equalized vertical contact Application of excessive closure pressure by the patient at the time of recording Changes in the supporting
  78. 78. Technical Errors may be caused by Ill fitting occlusal rims Indiscriminate opening or closing of the occluding device or articulator The slight shifting of the teeth which occurs between the stage of final arrangement and the transfer to a permanent base material. PROBLEM OF RECOGNIZING THE SYMPTOMS OF ERRORS ASSOCIATED WITH CENTRIC REALTION Symptoms Of Unequalized Vertical Contact Loss of retention Irritation on the crest of the lower ridge in the area of premature contact One tooth or several teeth on one side seem too long to the patient or seem to strike first The patient may complain of clicking if the teeth are porcelain premature contact anteriorly or posteriorly
  79. 79. Symptoms Of Error In Horizontal Relationship Anterior to CR o Looseness of lower denture o denture consciousness o Irritation under the anterior lingual flange of the lower denture Symptoms Of An Error In Horizontal Relationship Posterior to CR • Looseness, especially of lower denture • Irritation under the anterior labial flange of the lower denture (occasionally)
  80. 80. PROBLEMS OF RECORDING CENTRIC 1. The correctness of an individual registration is never assured until it is checked and verified by the observation of the operator 2. Methods Of Recording Centric • Limitations of Graphic recording • No control over the amount of closure pressure • Difficulty in placement of central bearing point when patients present extreme protrusion or retrusion of the mandible • Central bearing point is troublesome to use when patients present large clumsy tongues, extreme resorption of ridges or extensive amounts of displaceable tissues on the supporting areas.
  81. 81. Comparsion between intra oral and extra oral devices Heartwell states that intraoral tracings cannot be observed during tracing, therefore the method loses some of its value of a visible method. Since the intraoral tracings are very small, it is difficult to find a true apex. The tracer must be seated in a hole at the point of the apex to assure accuracy when recording the relation. If the patient moves the mandible before the occlusal rims are secured, the records shift on their basal seat, this destroys the accuracy of the record. The extra oral tracings are larger and therefore the patient can be directed and guided more intelligently during the mandibular movements. The stylus can be observed in the apex of the tracing during the process of injecting the plaster between the occlusal rims and recording the relation and no holes are required. Boucher prefers the extra oral device. Boucher also recommended that centric relation should be made with minimal pressure to prevent displacement of the tissues supporting
  82. 82. Solomon claimed that in intraoral method the errors are likely to be less because the tracing is situated closer to the centers of movements in the temporomandibular joint in comparison to the flexible extra oral device which inscribes mandibular movement in a plate situated outside the mouth further away from the centers of mandibular movement. Further the presence of extra oral tracer attachments prevents the lips from meeting each other and remains passive. According to him , the distinct advantage of intraoral tracing is the ability of the subject to perform mandibular movements with the lips in passive contact position.
  83. 83. Kapur K K and Yurkstas A A (1957) compared the duplicability of records using various techniques The intra oral tracing procedure (hardy) The wax registration procedure (hanau) The extra oral tracing procedure (stansberry) He concluded that •The intra oral and extra oral procedures were more consistent compared the wax registration method •The intra oral and extra oral procedures became less consistent in patients with flabby ridges as compared to patients with good and flat ridges •The consistency of the extra oral procedure did not vary significantly with different types of ridges •The degree of consistency with the intra oral procedure decreased to a significant level in patients flabby ridges •The wax method was less consistent than the other two procedures. It showed least consistency on flat ridges and the highest consistency on flabby ridges
  84. 84. REVIEW OF LITERATURE In 1910 –Gysi stated needle points tracing has been accepted as an accurate method of locating the centric maxillomandibular relation at a given degree of jaw separation. In 1940 – Boos in his study in maxillomandibular relations established by biting power stated in his research on maxillomandibular relationship with the use of the power point, reports that centric relation is not at the apex of the gothic arch. He stated that he found by use of resultant biting power (point) that the needle point tracing is extremely accurate in some patient and in others it is unreliable, the resultant biting point is located at apex of the needle point tracing in some patient, anterior to the apex in others. In 1952 – Granger stated that the apex of the Gothic arch tracing shows a sharp apex. It does however have one value. In order to do an accurate tracing it is necessary to do two tracing one on each side of the mandible.
  85. 85. In 1954 – Stansbery proposes a method to check the correctness of the central bearing position. One rod it passed through the a needle holder and other placed on the tracing plate. They should be parallel in all directions.
  86. 86. In 1959 – Elmer E Francis in his article jaw relation in C D construction described vertical tracer is that which registers and determines the proper vertical dimension, centric relation and condyle path records. This vertical dimension is result of study of Gysi. Horizontal position of the mandible is registered by the gothic arch tracing. Vertical tracer consist of upper and lower metal plate which are shaped like balanced occlusal guide plates. These two plates are attached to upper and lower base plates, upper plate has a vertical plate and a gothic arch tracer. The lower plate has a horizontal tracing table, an intra oral removable screw attachment that constitute vertical stop and slip joints which holds Gysi face bow and a vertical marker. In 1961 – Huges and Regli : In his study of what is centric relation observed that a sharp gothic arch tracing may be obtained with the condyles in more than one location in the glenoid fossa. When using a central bearing point for patients with prognathic or orthognathic occlusions it is difficult, not if possible to secure equalization of pressure.
  87. 87. In 1962 – Jones PM : In his study of eleven aids for a better CD stated in intra oral gothic arch tracer is used to determine the centric relation at the established vertical relation. The needle point tracing device is a reliable, accurate and practical method for locating centric relation. The apex of a tracing is indented with a bur. A plaster intra occlusal record is made by injecting plaster into the patients mouth with the Stanberry plaster syringe. In 1965 – Mohammed A, W Arthur George and Russel H Scott : summarized Needle point tracing were obtained from ten subjects at five different degree of jaw separation. Two subject showed negligible lateral deviation at any degree of opening when one subject showed consistent deviation from midline when the vertical dimension between the jaw was increased The needle point tracing at a given vertical dimension of jaw separation under same controlled condition, on the same individual at same sitting were not significantly different. So needle point tracing is reliable.
  88. 88. In 1968, Joseph E Grasso and John sharry in the study of the duplicability of arrow point tracing in dentulous patients did a study with 15 white men (Detail students between age group of 20 – 35) tracing were obtained at a fixed vertical dimension for each subject. The vertical jaw separation varied from subject to subject depending upon the cuspal teeth height of the posterior teeth and or the vertical overlap of the anterior teeth. Variation pattern of the apex position of the needle point tracing were greater in an anteroposterior direction than in a mediolateral direction.
  89. 89. In 1969 – A langer and J. Michmann studying the intra oral technique for recording vertical and horizontal maxillomandibular relation in complete dentures wrote that the instrument used the Barnae stylus tracer is an intra oral tracing device. This technique is recording vertical and horizontal maxillomandibular relation is suggested. This technique fulfils basic requirements for correct complete denture construction. The physiologic rest position is used as a reference for establishing an acceptable interocclusal distance and the most retruded mandibular position is recorded in centric relation. The use of central bearing point ensures equal distribution of pressure throughout the basal seat while the records are made. In 1970 – Clayton, Kotowiez and Myers : conducted a research on graphic recording of mandibular movements concluded the orientation of styli and recording table affected graphic tracing of mandibular movements when the vertical dimension is changed, cusp gliding on inclines involves change in vertical
  90. 90. In 1975 – Smith in study in comparison of empirical centric relation record and location of terminal hinge axis and apex of the gothic arch tracing concluded that average empirical determination provided a centric relation point anterior to that determined by either the gothic arch and the hinge axis location . Gothic arch method was the most repeatable of the three methods. In 1980 – Michael Myer in his article relation of gothic arch apex to dentist assisted centric relation concluded that thumb pressure can position the mandible consistently more posterior than the position indicated by the gothic arch apex is unfounded. It also states that dentist assisted jaw relation is more reproducible than relation indicating gothic arch apex.
  91. 91. In 1987 – Winstanly : In his article gothic arch tracing and condylar inclination concluded that records and the patient referred for treatment of temperomandibular joint disorders were used to compare condylar inclination found by drawing a tangent and by using a mathematical technique. Needle point tracing angles were also measured for the same patient and were compared with the condylar inclination. It can be concluded that the mathematical technique outlines records a more accurate value between patient and L & R sides of the same patient and there is no direct relationship between condylar inclination and the needle point tracing angle.
  92. 92. In 1989 – Winstanly : in his article the gothic arch tracing and the upper canine teeth as guide in the positioning of the upper posterior teeth concluded that the relationship between the position of the buccal cusps of the natural upper posterior teeth and the distance between the upper canine teeth has been found to be constant within + 1-2mm this may be of value when setting up artificial teeth for denture patients, enabling them to be positioned close to the natural predecessors.
  93. 93. 1996 Obrez A, Stohler CS conducted a study to test whether pain can cause significant changes in position of the mandible and therefore form the basis for any perceived changes in the maxillomandibular relationship. A second objective was to determine whether pain can cause changes in the mandibular range of motion. Five subjects who rated pain intensity on a visual analog scale were used in a single-blind, randomized, repeated-measures study design. Tonic muscle pain was induced by infusion of 5% hypertonic saline solution into the central portion of the superficial masseter muscle. Isotonic saline solution was used as a control, with subjects blinded to the type of substance given. The effect of pain on the position of the apex of the gothic arch tracing, the direction of the lateral mandibular border movements, and the mandibular range of motion was studied in a horizontal plane with minimal occlusal separation. Pain significantly affected the position of the apex of the gothic arch tracing in anterior Similarly, pain affected the orientation of the mandibular lateral border movements and their magnitude
  94. 94. All pain-induced effects proved to be reversible. The observed effect of pain can explain the perceived change of bite that is frequently noted by patients with orofacial pain. This study provided evidence of an alternative causal relationship between pain and changes in occlusal relationship and questions occlusal therapy as treatment, directed toward the elimination of the underlying cause in patients with masticatory muscle pain.
  95. 95. 1998 Raigrodski AJ, Sadan A, Carruth PL Clinicians have long expressed concern about the accuracy of the Gothic arch tracing for recording centric relation in edentulous patients. With the use of dental implants to assist in retaining complete dentures, the problem of inaccurate recordings, made for patients without natural teeth, can be significantly reduced. This article presents a technique that uses healing abutments to stabilize the record bases so that an accurate Gothic arch tracing can be made. 1999 Watanabe Y Analyzed and evaluated the horizontal mandibular positions produced by different guidance systems. Twenty-six edentulous subjects with no clinical evidence of abnormality of temporomandibular disorder were selected. Horizontal position data for the mandible obtained by gothic arch tracing was loaded into a personal computer by setting the sensor portion of a digitizer into the oral cavity to serve as a miniature lightweight tracing board.
  96. 96. By connecting this with a digitizer control circuit set in an extraoral location, each mandibular position was displayed in a distinguishable manner on a computer display in real time, then recorded and analyzed. The gothic arch apex and tapping point varied, depending on body position. In the supine position, the gothic arch apex and the tapping point were close to the mandibular position determined by bilateral manipulation. This system provides effective data concerning mandibular positions for fabrication of dentures. 2003 Keshvad A, Winstanley RB. conducted to determine statistically the most repeatable mandibular position of 3 centric relation methods. Three centric relation recording methods commonly reported in the literature were selected: bimanual mandibular manipulation with a jig, chin point guidance with a jig, and Gothic arch tracing. Fourteen healthy adult volunteers (7 males and 7 females), with an average age of 26 years and no history of extractions, temporomandibular joint dysfunction, or orthodontic treatment, were selected for the
  97. 97. Accurate casts were mounted on an articulator (Denar D4A) by means of a facebow and maximum intercuspation silicone registration record. A mechanical 3-dimensional mandibular position indicator was constructed and mounted on the articulator enabling the operator to analyze the mandibular positions in 3 spatial axes (x, anteroposterior; y, superoinferior; z, mediolateral shift). Each centric relation method was recorded four times on each subject (at baseline, 1 hour, 1 day, and 1 week at approximately the same time of day). Records were transferred to the articulator, and data were extracted using a stereomicroscope modified to accept the mandibular position indicator. The results of this study showed that of the 3 centric relation methods evaluated, the bimanual manipulation method positioned the condyles in the temporomandibular joint with a more consistent repeatability than the other 2 methods, whereas the Gothic arch was the least consistent method.
  98. 98. REFERENCES •El-Gheriani AS, Winstanley RB.The Gothic arch (needle point) tracing and condylar inclinationJ Prosthet Dent. 1987 Nov;58(5):638-42. •El-Gheriani AS, Winstanley RB.The value of the Gothic arch tracing in the positioning of denture teeth. J Oral Rehabil. 1988 Jul;15(4):367-71. •El-Gheriani AS, Davies AL, Winstanley RB.The gothic arch tracing and the upper canine teeth as guides in the positioning of upper posterior teeth. J Oral Rehabil. 1989 Sep;16(5):481-90. •Honorato Villa: Gothic arch tracing:JPD; 1959:9:624-628 •Howard F. Smith: A comparison of empirical centric relation records with location of terminal hinge axis and the apex of the Gothic arch tracing ; JPD 1975 : 33:511-520
  99. 99. •Keshvad A, Winstanley RB. :Comparison of the replicability of routinely used centric relation registration techniques : Prosthodont. 2003 Jun;12(2):90-101. •Max A Pleasure: occlusion of cuspless teeth for balance and comfort JPD: 1955:5:305-312 •Obrez A, Stohler CS.Jaw muscle pain and its effect on gothic arch tracings. J Prosthet Dent. 1996 Apr;75(4):393-8. •Raigrodski AJ, Sadan A, Carruth PL.A technique to stabilize record bases for Gothic arch tracings in patients with implant-retained complete dentures. J Prosthodont. 1998 Dec;7(4):273-6. •Vincent R Trapozzano: An analysis of current concepts of occlusion: JPD: 1955:5 764-782 •Watanabe Y.:Use of personal computers for Gothic arch tracing: analysis and evaluation of horizontal mandibular positions with edentulous prosthesis.: J Prosthet Dent. 1999 Nov;82(5):562-72.
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