Abstract:
A dentally retained intra-oral appliance worn at night for treatment of snoring and obstructive sleep apnea and its fabrication process. The appliance maintains the patient&#39;s mandible in an anterior, protruded position to prevent obstruction of the pharyngeal airway. The appliance allows a limited degree of lateral movement of the mandible relative to the upper jaw in the protruded position to prevent aggravation of the patient&#39;s temporomandibular joint and associated muscles and ligaments. The appliance includes a lower bite block conforming to the patient&#39;s mandibular dentition, an upper bite block conforming to the patient&#39;s maxillary dentition, and a hinge connecting the upper bite block to the lower bite block. The upper bite block and the lower bite block are thin walled polyamide eliminating the need for dental wires to maintain them to the mandibular detention and the maxillary dentition and the problems associated therewith.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a bite block. More particularly, the present invention relates to a flexible retentive bite block and fabrication process. 
     2. Description of the Prior Art 
     Snoring and Obstructive sleep apnea are typically caused by complete or partial obstruction of an individuals pharyngeal airway during sleep. Usually, airway obstruction results from the apposition of the rear portion of the tongue or soft palate with the posterior pharyngeal wall. 
     Obstructive sleep apnea is a potentially lethal disorder in which breathing stops during sleep for 10 seconds or more, sometimes up to 300 times per night. Snoring occurs when the pharyngeal airway is partially obstructed, resulting in vibration of the oral tissues during respiration. These sleep disorders tend to become more severe as patients grow older, likely as a result of a progressive loss of muscle tone in the patient&#39;s throat and oral tissues. 
     Habitual snoring and sleep apnea have been associated with other potentially serious medical conditions, such as hypertension, ischemic heart disease and strokes. Accordingly, early diagnosis and treatment is recommended. 
     One surgical approach, known as uvulopalatopharyngoplasty, involves removal of a portion of the soft palate to prevent closure of the pharyngeal airway during sleep. This operation, however, is not always effective and may result in undesirable complications, such as nasal regurgitation. 
     A wide variety of non-surgical approaches for treating sleep disorders have been proposed including the use of oral cavity appliances. It has been previously recognized that movement of the mandible (lower jaw) forward relative to the maxilla (upper jaw) can eliminate or reduce sleep apnea and snoring symptoms by causing the pharyngeal air passage to remain open. 
     Several intra-oral dental appliances have been developed which the user wears at night to fix the mandible in an anterior, protruded (i.e. forward) position. Such dental appliances essentially consist of acrylic or elastomeric bite blocks, similar to orthodontic retainers or athletic mouth guards, which are custom-fitted to the user&#39;s upper and lower teeth and which may be adjusted to vary the degree of anterior protrusion. 
     While prior art dental appliances have proven effective in maintaining the mandible in a protruded position to improve airway patency, they often result in undesirable side effects. One of the most common side effects is aggravation of the temporomandibular joint and related jaw muscles and ligaments, especially in individuals who have a tendency to grind their teeth during sleep. 
     Aggravation of the temporomandibular joint has been associated with a wide variety of physical aliments, including migraine headaches. Accordingly, many individuals suffering from sleep apnea and snoring disorders are not able to tolerate existing anti-snoring dental appliances for long periods of time. 
     The need has therefore arisen for a dental appliance for treatment of snoring and sleep apnea which will maintain the mandible in a preferred anterior position, allow a limited degree of lateral excursion of the mandible relative to the upper jaw to avoid discomfort to the temporomandibular joint and related muscles and ligaments, and be replaceably maintained on the user&#39;s teeth by virtue of its own flexibility and thereby eliminating the need for dental wires that can aggravate the teeth and gums and which requires the appliance to have thick walls for their support which can lead to further discomfort for the user, such as gum and cheek irritation and gagging. 
     Numerous innovations for mouthpieces have been provided in the prior art that will be described. Even though these innovations may be suitable for the specific individual purposes to which they address, however, they differ from the present invention. 
     FOR EXAMPLE, U.S. Pat. No. 5,203,324 to Kinkade teaches a mouthpiece for use in diving or medical equipment, among others made of moldable resilient material having an offset between upper and lower jaw, a bite plane which is tapered with the bite plane formed by wings which have varying thickness to create the taper in which the wing members have substantially vertical surfaces on either side thereof for contacting the lateral surfaces of the user&#39;s cuspids and bicuspids and in which the main body portion has upper and lower apron and eminence skirts for avoiding contact with the user&#39;s frenum and cuspid eminences and in which the internal wing members have a range in size, at the cuspid, from about 6 to about 12 mm in width, from about 14 to about 40 mm in length and from about 2 mm to about 8 mm in thickness. The greater the offset, the shorter the length of the internal wind members. 
     ANOTHER EXAMPLE, U.S. Pat. No. 5,365,945 to Halstrom teaches a dentally retained intra-oral appliance worn at night for treatment of snoring and obstructive sleep apnea. The appliance maintains the patient&#39;s mandible in an anterior, protruded position to prevent obstruction of the pharyngeal airway. The appliance allows a limited degree of lateral movement of the mandible relative to the upper jaw in the protruded position to prevent aggravation of the patient&#39;s temporomandibular joint and associated muscles and ligaments. 
     As shown in FIG. 1, the appliance 10 preferably consists of a lower bite block 12 conforming to the patient&#39;s mandibular dentition 14, an upper bite block (not shown, but constructed similar to the lower bite block 12) conforming to the patient&#39;s maxillary dentition (not shown), and a connecting assembly (not shown) secured to an anterior region (not shown) of the upper (not shown) and lower bite blocks 12. 
     Unfortunately, the apparatus 10 requires dental wires 16 to maintain it to the mandibular detention 14 and the maxillary dentition (not shown). The dental wires 16 are embedded in the appliance 10 and bias against the mandibular detention 14 and the maxillary dentition (not shown), causing discomfort to the wearer, especially those with sensitive teeth. To support the dental wires 16, the walls 20 of the appliance 10 are thick, which lead to further discomfort for the user, such as inter alia gum, tongue, palate, and cheek irritation. 
     With the dental wires 16 being biased when worn, they are under stress and exert a stress on the walls 20 of the appliance 10 housing them. The stress can cause the walls 12 of the appliance 10 to fracture, splinter, or cause the dental wires 16 to separate from the appliance. 
     Furthermore, the appliance 10 includes a pair of opposing bite pads 22 that are separate and affixed on the biting surfaces 24 of the posterior portions 26 of the appliance 10; they are thereby subject to dislodgement from the appliance 10. 
     In contradistinction, however, as shown in FIG. 2, the flexible retention bite block 30 of the present invention requires no dental wires to maintain it to the mandibular detention 14 and the maxillary dentition (not shown), eliminating discomfort to the wearer, especially those with sensitive teeth. Absent the dental wires, the walls 32 of the appliance 10 are thin, eliminating further discomfort to the user, such as inter alia gum, tongue, and cheek irritation. 
     Absent the dental wires and the biasing associated therewith, no stress is exerted on the walls 32 of the flexible retention bite block 30, eliminating fracture, splinter, of the walls 32. 
     Furthermore, the flexible retention bite block 30 includes a pair of opposing bite pads 34 that are integrally formed on the biting surfaces 24 of the posterior portions 26 of the flexible retentive bite block 30; they are therefore not subject to dislodgement from the flexible retention bite block 30. 
     The flexible retentive bite block 30 is maintained on the mandibular detention 14 and the maxillary dentition (not shown), by virtue of its side walls 32 extending 1 mm past and capturing the supra bulge 36 of the mandibular detention 14 and the maxillary dentition (not shown), and the inherent flexibility of the polyamide material it is made of. 
     STILL ANOTHER EXAMPLE, U.S. Pat. No. 5,409,017 to Lowe teaches a mandible repositioning appliance formed by an upper bite block and a lower bite block interconnected by an adjustable mechanism including a posterior section connected to the rear portion of the upper bite block and an anterior section connected to the front portion of the lower bite block and an adjustable interconnection between the anterior and posterior sections. Preferably, the adjustable interconnection includes a double thread element rotation of which changes the relative positions of the posterior and interior sections axially of the appliance and abutments to define each incremental rotation of the element. The comfort of the wearer is further improved by using a heat sensitive material in the tooth retention sections and by permitting limited relative lateral movement between the bite blocks. 
     YET ANOTHER EXAMPLE, U.S. Pat. No. 5,499,633 to Fenton teaches an adjustable oral device for placement within the mouth of a user to reduce or eliminate snoring. The device comprises an upper member having a substantially curved shape and defining an upwardly oriented channel for receiving at least some of the upper teeth of a user. A lower member has a substantially curved shape and defines a downwardly oriented channel for receiving at least some of the lower teeth of a user. The upper member is adjustably coupled by the user to the lower member in a spaced relationship such that the lower member is positioned relative to the upper member so that when the user&#39;s teeth are retained within the device, the user&#39;s lower jaw is biased substantially forward of its normal biting or resting position to reduce snoring. The device can include an anterior tongue space between the upper and lower members, and can further include moldable material positioned within at least one of the channels for substantially conforming to a shape of the teeth, thus allowing the device to be customized for individual users. 
     FINALLY, YET STILL ANOTHER EXAMPLE, U.S. Pat. No. 5,562,106 to Heeke et al. teaches a non-surgical oral appliance for improving breathing, and abating or completely alleviating snoring sounds and symptoms while sleeping. The patient is pre-tested and pre-fitted for the appliance so that the appliance positions the mandible in an open position and protrusive position to hold the mouth partially open. The appliance has a right and left extension wherein each extension has upper and lower surfaces pre-molded to the contour of the patient&#39;s back teeth. A bridge connects the right and left extensions having been pre-molded to conform to the upper palate of the patient&#39;s mouth. The upper and lower surfaces of each extension are spaced to provide optimum mouth height that was pre-tested to alleviate the snoring sound. Upon insertion, the appliance facilitates an air passage for breathing and also allows the patient to talk while remaining virtually invisible to an observer. 
     It is apparent that numerous innovations for mouthpieces have been provided in the prior art that are adapted to be used. Furthermore, even though these innovations may be suitable for the specific individual purposes to which they address, however, they would not be suitable for the purposes of the present invention as heretofore described. 
     SUMMARY OF THE INVENTION 
     ACCORDINGLY, AN OBJECT of the present invention is to provide a flexible retentive bite block and fabrication process that avoids the disadvantages of the prior art. 
     ANOTHER OBJECT of the present invention is to provide a flexible retentive bite block and fabrication process that is simple and inexpensive to manufacture. 
     STILL ANOTHER OBJECT of the present invention is to provide a flexible retentive bite block and fabrication process that is simple to use. 
     BRIEFLY STATED, YET ANOTHER OBJECT of the present invention is to provide a dentally retained intra-oral appliance worn at night for treatment of snoring and obstructive sleep apnea and its fabrication process. The appliance maintains the patient&#39;s mandible in an anterior, protruded position to prevent obstruction of the pharyngeal airway. The appliance allows a limited degree of lateral movement of the mandible relative to the upper jaw in the protruded position to prevent aggravation of the patient&#39;s temporomandibular joint and associated muscles and ligaments. The appliance includes a lower bite block conforming to the patient&#39;s mandibular dentition, an upper bite block conforming to the patient&#39;s maxillary dentition, and a hinge connecting the upper bite block to the lower bite block. The upper bite block and the lower bite block are thin walled polyamide eliminating the need for dental wires to maintain them to the mandibular detention and the maxillary dentition and the problems associated therewith. 
     The novel features which are considered characteristic of the present invention are set forth in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of the specific embodiments when read and understood in connection with the accompanying drawing. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     The figures on the drawing are briefly described as follows: 
     FIG. 1 is a diagrammatic side elevational view, in partial cross sectional, of a prior art bite block taught by U.S. Pat. No. 5,365,945 to Halstrom, installed on a patient&#39;s teeth; 
     FIG. 2 is a diagrammatic side elevational view, in partial cross sectional, of the apparatus of the present invention installed on a patient&#39;s teeth; 
     FIG. 3 is a diagrammatic side elevational view illustrating the step of surveying a tooth of the model as further illustrated by steps 3, 4, 17 and 18 of the fabrication process of the present invention; 
     FIG. 4 is a diagrammatic side elevational view partially in section, with parts broken away, illustrating the plastic spacer layer being applied and conformed to the model as further illustrated by steps 6, 7, 8, 20, 21, and 22 of the fabrication process of the present invention; 
     FIG. 5 is a diagrammatic perspective view illustrating a metal bite pads about to be attached to the model with luting agent as further illustrated by steps 10 and 24 of the fabrication process of the present invention; 
     FIG. 6 is an exploded diagrammatic perspective view illustrating various components utilized in the fabricating of the upper and lower bite blocks with their typical relative locations to each other as further illustrated by steps 12, 13, 14, 26, 27, 28 and 29 of the fabrication process of the present invention; 
     FIG. 7 is an exploded diagrammatic perspective view illustrating a flask being made ready for closure as further illustrated by steps of steps 62, 63, 64 and 65 of the fabrication process of the present invention; 
     FIG. 8 is an exploded diagrammatic perspective view of steps 81 and 82 of the process of the present invention, and also shows the final assemblage of the article of manufacture the flexible retentive bite blocks of present invention produced by the fabrication process of the present invention; and 
     FIGS. 9A-9MM is a process flow diagram for carrying out the fabrication process of the present invention. 
     LIST OF REFERENCE NUMERALS UTILIZED IN THE DRAWING 
     Prior Art 
     10 appliance 
     12 lower bite block 
     14 patient&#39;s mandibular dentition 
     16 dental wires 
     20 walls of appliance 10 
     22 pair of opposing bite pads 
     24 biting surfaces 24 of posterior portions 26 
     26 posterior portions 
     Present Invention 
     30 flexible retention bite block 
     32 walls 
     34 pair of opposing bite pads 
     36 supra bulge of mandibular detention 14 
     38 lower duplicate casting 
     40 gum of lower duplicate casting 38 
     42 teeth of lower duplicate casting 38 
     44 cross section of mounting surface of articulator with parts broken away 
     46 surveying line of teeth 42 of lower duplicate casting 38 
     48 extended surveying line of teeth 42 of lower duplicate casting 38 
     50 heat pressure former 
     52 at least one plastic spacer sheet 
     54 conformed plastic spacer layer on lower duplicate casting 38 
     56 pair of opposing metal bite pads on conformed plastic spacer layer 54 on lower duplicate casting 38 
     57 lower pattern 
     58 lower processing stylus 
     60 guide box 
     62 narrow stub portion of lower processing stylus 58 
     64 base plate 
     66 processing screws 
     67 lower assemblage 
     68 upper duplicate casting 
     70 gum of upper duplicate casting 68 
     72 teeth of upper duplicate casting 68 
     74 supra bulges of teeth 72 of upper duplicate casting 68 
     76 surveying line of upper duplicate casting 68 
     78 extended surveying line of upper duplicate casting 68 
     80 at least one plastic spacer sheet 
     82 conformed plastic spacer layer on upper duplicate casting 68 
     84 pair of opposing metal bite pads on conformed plastic spacer layer 82 on upper duplicate casting 68 
     85 upper pattern 
     86 retention plate 
     88 aperture in retention plate 86 
     90 part of upper processing jig 92 
     92 upper processing jig 
     94 non-threaded portion 94 of final stylus 96 
     96 final stylus 
     98 threaded portion 98 of final stylus 96 
     100 upper assemblage 
     102 stone 
     103 upper bite block 
     104 lower portion 104 of flask 106 
     105 lower bite block 
     106 flask 
     108 upper portion of flask 106 
     110 wax sprue on upper assemblage 100 
     112 wax sprue on lower assemblage 67 
     113 pair of permanent screws 
     114 head of lower processing stylus 58 
     116 milled-out cavity in guide box 60 
     118 shaft of lower processing stylus 58 
     120 kidney-shaped aperture in upper surface 122 of guide box 60 
     122 upper surface of guide box 60 
     124 head of each of processing screws 66 
     126 shaft of each of processing screws 66 
     128 three non-threaded apertures 122 in base plate 64 
     130 stub portion of each of processing screws 66 
     132 pair of threaded apertures 126 in guide box 60 
     134 shaft of each of processing screws 66 
     136 base of processing jig 92 
     138 center portion of base 36 of processing jig 92 
     140 aperture in center portion 138 of base 36 of processing jig 92 
     142 pair of opposing wing portions of base 36 of processing jig 92 
     144 plurality of stub portions of processing jig 92 
     146 head of final stylus 96 
     148 head of each of pair of permanent screws 113 
     150 shaft of each of pair of permanent screws 113 
     152 stub portion of each of pair of permanent screws 113 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The fabrication process of the flexible retentive bite block 30 can best be seen in FIGS. 3 through 9MM inclusive, and as such will be discussed with reference thereto. 
     STEP 1: Make a optional duplicate of an original lower casting forming a lower duplicate casting 38 having a gum 40, teeth 42 with the supra bulges 36 and posterior portions with bite surfaces. 
     STEP 2: Mount the lower duplicate casting 38 on an articulator 44. 
     STEP 3: As shown in FIG. 3, survey the lower duplicate casting 38 forming a surveying line 46 thereon. 
     STEP 4: As shown in FIG. 3, extend the surveying line 46 approximately 1 mm past the supra bulges 36 of the teeth 42 of the lower duplicate casting 38, toward the gum 40 of the lower duplicate casting 38, forming an extended surveying line 48. 
     STEP 5: Remove the lower duplicate casting 38 from the articulator 44. 
     STEP 6: As shown in FIG. 4, put the lower duplicate casting 38 in a heat pressure former 50. A typical heat pressure former 50 is sold by either ERKOPRESS or BIOSTAR. 
     STEP 7: As shown in FIG. 4, position at least one plastic spacer sheet 52 on the teeth 42 of the lower duplicate casting 38. 
     Step 8: As shown in FIG. 4, activate the heat pressure former 50 causing the at least one plastic spacer sheet 52 to melt and conform to the teeth 42 of the lower duplicate casting 38 forming a conformed plastic spacer layer 54 thereon. 
     STEP 9: Remove the lower duplicate casting 38 with the conformed plastic spacer layer 54 thereon from the heat pressure former 50. 
     STEP 10: As shown in FIG. 5, affix a pair of opposing metal bite pads 56 on the conformed plastic spacer layer 54, at the bite surfaces of the posterior portions of the teeth 42 of the lower duplicate casting 38, utilizing a wax luting agent, and forming therewith a lower pattern 57 (see FIG. 6). 
     STEP 11: Replace the lower duplicate casting 38 with the lower pattern 57 thereon on the articulator 44. 
     STEP 12: As shown in FIG. 6, position a lower processing stylus 58 in a guide box 60 of a hinge, wherein the lower processing stylus 58 has a narrow stub portion 62. 
     STEP 13: As shown in FIG. 6, secure the guide box 60 of the hinge to a base plate 64 of the hinge, by processing screws 66. 
     STEP 14: As shown in FIG. 6, secure the base plate 64 of the hinge to the lower duplicate casting 38, utilizing the wax luting agent, forming a lower assemblage 67. 
     STEP 15: Make a optional duplicate of an original upper casting forming an upper duplicate casting 68 having a gum 70, teeth 72 with supra bulges 74 and posterior portions with bite surfaces. 
     STEP 16: As shown in FIG. 3, mount the upper duplicate casting 68 on the articulator 44. 
     STEP 17: As shown in FIG. 3, survey the upper duplicate casting 68, forming a surveying line 76 thereon. 
     STEP 18: As shown in FIG. 3, extend the surveying line 76 approximately 1 mm past the supra bulges 74 of the teeth 72 of the upper duplicate casting 68, toward the gum 70 of the upper duplicate casting 68, forming an extended surveying line 78. 
     STEP 19: Remove the upper duplicate casting 68 from the articulator 44. 
     STEP 20: As similarly shown in FIG. 4, put the upper duplicate casting 68 in the heat pressure former 50. 
     STEP 21: As similarly shown in FIG. 4, position at least one plastic spacer sheet 80 on the teeth 72 of the upper duplicate casting 68. 
     STEP 22: As similarly shown in FIG. 4, activate the heat pressure former 50 causing the at least one plastic spacer sheet 80 to melt and conform to the teeth 72 of the upper duplicate casting 68, forming a conformed plastic spacer layer 82 thereon. 
     STEP 23: Remove the upper duplicate casting 68 with the conformed plastic spacer layer 82 thereon from the heat pressure former 50. 
     STEP 24: As similarly shown in FIG. 5, affix a pair of opposing metal bite pads 84 on the conformed plastic spacer layer 82, at the bite surfaces of the posterior portions of the teeth 72 of the upper duplicate casting 68, utilizing the wax luting agent, and forming therewith an upper pattern 85 (see FIG. 6). 
     STEP 25: Replace the upper duplicate casting 68 with the upper pattern 85 thereon on the articulator 44. 
     STEP 26: As shown in FIG. 6, set a retention plate 86 on the lower processing stylus 58, with the narrow stub portion 62 of the lower processing stylus 58 removably entering into an aperture 88 in the retention plate 86 assuring proper alignment of the retention plate 86 when securing the retention plate 86 to the upper pattern 85. 
     STEP 27: As shown in FIG. 6, secure the retention plate 86 of the hinge to the upper pattern 85, utilizing the wax luting agent. 
     STEP 28: As shown in FIG. 6, position a part 90 of an upper processing jig 92 into the retention plate 86 of the hinge. 
     STEP 29: As shown in FIG. 6, secure the upper processing jig 92 to the retention plate 86, by passing a non-threaded portion 94 of a final stylus 96 through the upper processing jig 92, with a threaded portion 98 of the final stylus 96 threadably engaging the aperture 88 in the retention plate 86, forming an upper assemblage 100. 
     STEP 30: Remove the upper assemblage 100 from the articulator 44. 
     STEP 31: Apply the separating medium to exposed portions of the upper assemblage 100. 
     STEP 32: As shown in FIG. 7, position stone 102 in a lower portion 104 of a flask 106 that has an upper portion 108. 
     STEP 33: As similarly shown in FIG. 7, place the upper assemblage 100 in the lower portion 104 of the flask 106. 
     STEP 34: As similarly shown in FIG. 7, place a wax sprue 110 on the upper assemblage 100. 
     STEP 35: As shown in FIG. 7, position additional stone 102 in the lower portion 104 of the flask 106 to the extended surveying line 78. 
     STEP 36: Apply the separating medium to exposed stone and the upper pattern 85. 
     STEP 37: Secure the upper portion 108 of the flask 106 to the lower portion 104 of the flask 106. 
     STEP 38: Fill the upper portion 108 of the flask 106 with additional stone 102. 
     STEP 39: Harden contents of the flask 106, forming an upper bite block mold. 
     STEP 40: Remove the wax luting agent and the wax sprue 110 from the upper bite block mold, utilizing boiling water, with the retention plate 86 of the hinge retained in the upper bite block mold. 
     STEP 41: Separate the upper portion 108 of the flask 106 from the lower portion 104 of the flask 106. 
     STEP 42: Pick out the conformed plastic spacer layer 80 and the pair of opposing metal bite pads 84 from the upper bite block mold. 
     STEP 43: Apply the separating medium to the upper bite block mold. 
     STEP 44: Preheat the upper portion 108 of the flask 106 and the lower portion 104 of the flask 106 under heat lamps. 
     STEP 45: Heat polyamide material forming preheated polyamide material. A typical polyamide material is sold by RAPID INJECTION SYSTEMS CORP. 
     STEP 46: Secure the upper portion 108 of the flask 106 to the lower portion 104 of the flask 106. 
     STEP 47: Inject the preheated polyamide material into the flask 106, forming an upper bite block 103 (see FIG. 8) having the retention plate 86 of the hinge embedded therein. 
     STEP 48: Cool the flask 106. 
     STEP 49: Separate the upper portion 108 of the flask 106 from the lower portion 104 of the flask 106. 
     STEP 50: Remove the upper bite block 103 from the upper bite block mold. 
     STEP 51: Remove the final stylus 96. 
     STEP 52: Remove the processing jig 92. 
     STEP 53: Remove all rough edges from the upper bite block 103. 
     STEP 54: Smooth the upper bite block 103. 
     STEP 55: Check and adjust the upper bite block 103, as required. 
     STEP 56: Polish the upper bite block 103, forming a finished upper bite block. 
     STEP 57: Transfer the finished upper bite block to the original upper casting, forming a final upper assemblage. 
     STEP 58: Put the final upper assemblage On the articulator 44. 
     STEP 59: Remove the lower assemblage 67 from the articulator 44. 
     STEP 60: Apply the separating medium to exposed portions of the lower assemblage 67. 
     STEP 61: As shown in FIG. 7, position stone 102 in the lower portion 104 of the flask 106. 
     STEP 62: As shown in FIG. 7, place the lower assemblage 67 in the lower portion 104 of the flask 106. 
     STEP 63: As shown in FIG. 7, place a wax sprue 112 on the lower assemblage 67. 
     STEP 64: Position additional stone 102 in the lower portion 104 of the flask 106 to the extended surveying line 48. 
     STEP 65: Apply the separating medium to exposed stone and the lower pattern 66. 
     STEP 66: Secure the upper portion 108 of the flask 106 to the lower portion 104 of the flask 106. 
     STEP 67: Fill the upper portion 108 of the flask 106 with additional stone 102. 
     STEP 68: Harden contents of the flask 106, forming a lower bite block mold. 
     STEP 69: Remove the wax luting agent and the wax sprue 112 from the lower bite block mold, utilizing boiling water, with the base plate 64 of the hinge retained in the lower bite block mold. 
     STEP 70: Separate the upper portion 108 of the flask 106 from the lower portion 104 of the flask 106. 
     STEP 71: Pick out the conformed plastic spacer layer 54 and the pair of opposing metal bite pads 56 from the lower bite block mold. 
     STEP 72: Apply the separating medium to the lower bite block mold. 
     STEP 73: Preheat the upper portion 108 of the flask 106 and the lower portion 104 of the flask 106 under the heat lamps. 
     STEP 74: Heat polyamide material forming preheated polyamide material. 
     STEP 75: Secure the upper portion 108 of the flask 106 to the lower portion 104 of the flask 106. 
     STEP 76: Inject the preheated polyamide material into the flask 106 forming a lower bite block 105 (see FIG. 8) having the base plate 64 of the hinge embedded therein. 
     STEP 77: Cool the flask 106. 
     STEP 78: Separate the upper portion 108 of the flask 106 from the lower portion 104 of the flask 106. 
     STEP 79: Remove the lower bite block 105 from the lower bite block mold. 
     STEP 80: Remove the processing screws 66, freeing the guide box 60 and the lower processing stylus 58. 
     STEP 81: As shown in FIG. 8, replace the lower processing stylus 58 with the final stylus 96. 
     STEP 82: As shown in FIG. 8, resecure the guide box 60 of the hinge to the base plate 64 of the hinge with permanent screws 106. 
     STEP 83: Remove all rough edges from the lower bite block 105. 
     STEP 84: Smooth the lower bite block 105. 
     STEP 85: Check and adjust the lower bite block 105, as required. 
     STEP 86: Polish the lower bite block 105, forming a finished lower bite block. 
     STEP 87: Transfer the finished lower bite block to the original lower casting, forming a final lower assemblage. 
     STEP 88: Put the final lower assemblage in the articulator 44. 
     STEP 89: Verify accuracy of bite registration of finished upper bite block and finished lower bite block, i.e. is bite registration accurate?. 
     STEP 90 Adjust accordingly, if answer to step 89 is no. 
     STEP 91 Secure the finished upper bite block to the finished lower bite block by threadably engaging the final stylus 96 into the retention plate 86, if answer to step 89 is yes, forming the flexible retentive bite block 30. 
     The configurations of the base plate 64, the guide box 60, and the retention plate 86 is of that taught by U.S. Pat. No. 5,365,945 to Halstrom. The configurations of the processing stylus 58, the processing screws 66, the processing jig 92, the final stylus 96, and the permanent screws 106, however, are different and will be discussed with reference to FIGS. 6 and 8. 
     As shown in FIG. 6, the processing stylus 58 has a head 114 that fills a milled-out cavity 116 in the guide box 60, and a shaft 118 that is non-threaded and extends coaxially from and is narrower than the head 1114 and enters a kidney-shaped aperture 120 in an upper surface 122 of the guide box 60, wherein the narrow stub portion 62 is non-threaded and extends coaxially from and is narrower than the shaft 118. 
     As shown in FIG. 6, each of the processing screws 66 has a head 124, a shaft 126 that is non-threaded and extends coaxially from and is narrower than the head 124 and passes through a respective outermost non-threaded aperture 128 of a pair of outermost non-threaded apertures 128 of three non-threaded apertures 128 in the base plate 64, a stub portion 130 that is threaded and extends coaxially from and is narrower than the shaft 126 and threadably engages a respective threaded aperture 132 of a pair of threaded apertures 132 in the guide box 60, and a shaft 134 that is non-threaded and extends coaxially from and is narrower than the stub portion 130 and extends past the upper surface 122 of the guide box 60 so as to prevent casting material from entering the pair of threaded apertures 132 in the guide box 60 during processing. 
     As shown in FIG. 6, the processing jig 92 has a base 136 that is flat, thin, and has a center portion 138 that is circular-shaped with an aperture 140 and a pair of opposing wing portions 142 that are rectangular-shaped and extend coplanarly from the center portion 138 of the base 136, wherein the part 90 of the processing jig 92 is a plurality of stub portions 144 that are cylindrically-shaped, spaced-apart, and extend perpendicularly from the base 136 and fill the aperture 88 in the retention plate 86 so as to prevent casting material from entering the aperture 88 in the retention plate 86 during processing. 
     As shown in FIG. 8, the final stylus 96 has a head 146 that is circular-shaped and moves laterally in the milled-out cavity 116 in the guide box 60, wherein the non-threaded portion 94 is a shaft 94 that extends coaxially from and is narrower than the head 146 and moves laterally in the kidney-shaped aperture 120 in the upper surface 122 of the guide box 60, and wherein the threaded portion 98 is a stub portion 98 that extends coaxially from and is narrower than the shaft 94 and threadably engages the aperture 88 in the retention plate 86. 
     As shown in FIG. 8, each of the permanent screws 113 has a head 148 that is circular-shaped and recessed in a respective outermost aperture of three non-threaded apertures in the lower bite block 105, a shaft 150 that is non-threaded and extends coaxially from and is narrower than the head 148 and passes through the respective outermost non-threaded aperture 128 of the pair of outermost non-threaded apertures 128 of the three non-threaded apertures 128 in the base plate 164, and a stub portion 152 that is threaded and extends coaxially from and is narrower than the shaft 150 and threadably engages the respective threaded aperture 132 of the pair of threaded apertures 132 in the guide box 60. 
     It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above. 
     While the invention has been illustrated and described as embodied in a flexible retentive bite block and fabrication process, however, it is not limited to the details shown, since it will be understood that various omissions, modifications, change in the order of steps, change in the number of or necessarity of optional duplicate castings, substitutions and changes in the forms and details of the device illustrated and its operation can be made by those skilled in the art without departing in any way from the spirit of the present invention. 
     Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute characteristics of the generic or specific aspects of this invention.