This page contains a Flash digital edition of a book.
Clinical Continued »


The early gnathologists studied the recorded tracings made during mandibular move- ments. When the mandible travels forward along the sagittal plane it is considered a protrusive excursion or protrusion. Therefore, retru- sion is the movement toward the posterior. It is the most retruded physiologic relation of the mandible to the maxilla to and from which the individual can make lateral movements that initially defined retruded axis position (RAP) or centric relation (CR) to the gnatholo- gist. Further investigations led the gnathologists to believe that mandibular (condylar) movements are governed by the three axes of rotation. The concept of retruded


axis position evolved into a three-dimensional position, resulting in its description as the rearmost, uppermost, and midmost (RUM) position of the condyles in the glenoid fossa. More recently, with the input of anatomists and physiologists, the concept has also included a bone-braced position slightly anterior to the RUM position. While there can be discussions between groups as to the exact definition of RAP, it is generally accepted as a muscular relaxed, reproduc- ible and braced position that is an area not a pinpoint and can only be achieved with relaxed musculature. Placing the condyles with


the correct position and having immediate disclusion (canine guidance and incisor guid- ance) upon movement away from that position, with no vertical or horizontal deflec- tive contacts is fundamental to gnathology. Tooth wear is considered pathological in gnathology and one of its fundamental concepts is trying to advance a dentition with minimal wear.


Alternative occlusal concepts: Pankey Mann Schuyler As gnathology was evolving, several competing occlusal


Fig 8 Anterior crowns front view


Fig 12


Intercuspal position with no anterior contacts


Fig 9 Fig 6


Upper right restoration on fully adjustable articulator


Upper arch occlusal view Fig 13 Upper anteriors


Fig 10


Upper right quadrant with palatal ramps


Fig 14 Upper anteriors final view


Fig 7


Upper left restoration on fully adjustable articulator


concepts and permutations were theorised, such as the Pankey Mann Schuyler (PMS) theory of occlusion. The PMS concepts evolved out of an initial study group headed by LD Pankey on the east coast of America. Nomen- clature was different and included centre relation (CR) instead of retruded axis posi- tion (RAP); centre-related occlusion (CRO) instead of retruded contact position (RCP) and centric occlusion (CO) instead of inter-cuspal position (ICP). Beyron, following his observations on Australian Aborgines, suggested that uniform tooth contact and resultant wear on several teeth in lateral occlusion was a positive and inevitable outcome. As a modification of canine


guidance, the PMS philos- ophy in complete full mouth


Fig 11


Upper left quadrant with palatal ramps


reconstruction was to have simultaneous contacts of the canine and posterior teeth in the laterotrusive (working) excursion, known as group function, and only anterior teeth contact in the protrusive excursive movement. Schuyler further suggested


that incisal guidance without freedom of movement from a centric-related occlusion (CRO) to a more anterior tooth intercuspation (CO) will ‘lock- in’ the posterior occlusion (long centric). The incisal guidance, along


with ‘long centric’, is deter- mined by the distance from transverse horizontal axis- centric relation and the normal freedom of movement in the envelope of function. This method requires that the incisal guidance be established and the mandibular posterior buccal cusps be placed to a


Fig 15 Lower anteriors final view


height measured along the occlusal plane as dictated by the curve of Monson. The maxillary posterior


teeth are developed after the completion of the mandibular restorations as dictated by a wax functionally generated path record. The definitive restorations are equilibrated into a centric relation posi- tion with mandibular buccal cusps onto a flattened fossae- marginal ridge contact with ‘freedom in centric’ anterior guidance and group function in laterotrusive (working) excursion.


Deflective contacts Though 90 per cent of natural dentitions have a deflective occlusal contact or an occlusal ‘prematurity’ between CRO and CO, it is usually in the


Continued » Scottish Dental magazine 55


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80  |  Page 81  |  Page 82  |  Page 83  |  Page 84  |  Page 85  |  Page 86  |  Page 87  |  Page 88