Where the teeth should be positioned in the face and jaws, and how to get them there by Thomas D. Creekmore Tom started his lecture by showing the initial records of four challenging clinical cases, asking the orthodontists in the audience how they would treat these difficult cases. At the end of his lecture he came back to show the treatment he performed on these four cases based on the concepts he developed during his presentation. The first concept Creekmore presented was that cephalometric norms or averages should not be used for skeletally non-average patients. He emphasized that the optimum position of the teeth in the face should be determined by the position of the maxillary incisors, rather than the mandibular incisors as, suggested by Tweed, Ricketts, and Steiner. Tom explained that Tweed advocated placing the mandibular incisors upright over basal bone at 90 degrees to the mandibular plane, plus or minus a small variation depending on the mandibular plane angle, to maintain an FMIA of 65 to 68 degrees. Creekmore stated that angulation of the mandibular incisors does not necessarily reflect A-P positions, concluding that the Tweed Triangle has serious limitations. Tom explained that the Ricketts analysis also was built around mandibular position. That it relates the mandibular incisor to the A-Po plane. Tom mentioned that a drawback to this plane is that it automatically changes the position of the incisor on the mandible as the jaw relationship changes. Tom then discussed the Steiner analysis. He explained that Steiner recommended varying maxillary and mandibular incisor positions according to the jaw relationships as indicated by the ANB angle. Creekmore pointed out that in the Steiner analysis as ANB varied from minus 1 degree to plus 6 degrees, maxillary incisor position changed by 7mm to NA while lower incisor position varied by only 1.75mm to NB. Tom pointed out that mandibular incisor position in the Steiner analysis remains fairly constant, while the position of the maxillary incisors varies a great deal to fit with the mandibular arch. Creekmore criticized this analysis because positioning teeth in the face again depends largely on the mandibular incisors. Another fact that Tom pointed out is that relating the mandibular incisor to NB does not truly reflect the position of the incisor on the mandible because B point and the entire dentition can be located far labially or lingually on the mandible and that that is the reason Holdaway modified the Steiner analysis to include Po-NB. In concluding this portion of his presentation Tom stated that the premise that mandibular incisor position determines optimum stability and facial esthetics is not valid. Creekmore then went on to discuss the fact that many Class II and III skeletal patterns have Class I occlusions with good esthetics as found by Casko who measured 79 cases from Tweed's 1954 sample. All the individuals in this sample had ideal occlusions and acceptable esthetics. Casko found a wide range of incisor positions and jaw relationships and concluded that many current systems of cephalometric evaluation would classify many of these patients as abnormal. While the mean ANB angle was indeed 2 degrees, the range was minus 3 degrees to plus 8 degrees, encompassing patients who would be classified as Class I, Class II and Class III skeletal patterns; yet they all had Class I occlusions with good esthetics. Thus, Creekmore emphasized that normal skeletal patterns may have a wide range of ANB angles. Tom showed two examples of extreme skeletal patterns, one with a severe Class III skeletal pattern but having a Class I occlusion, and another of a brachycephalic patient who had a dental Class II occlusion. In another study of 125 untreated adults with ideal facial and occlusal relationships McNamara found infinite combinations are possible to arrive at a face that is well balanced. Creekmore explained that this phenomenon is due to a compensatory mechanism: teeth migrate on the jaws to maintain a constant occlusal relationship, even though the maxilla and mandible are growing differently relative to each other in the three planes of space. Creekmore concluded this part of his presentation by emphasizing that our cephalometric goals are much too narrow. Creekmore's next topic dealt with his reasons for using the maxillary incisors to establish his treatment goals. He stated that the optimum position of the teeth in the face should be determined by the position of the maxillary incisors rather than the mandibular incisors. He explained that maxillary incisors maintain more constant their positions with changes in jaw relationship than the mandibular incisors. He stated that mandibular incisor position varies two and a half times more than maxillary incisors, with jaw relationship variations. He referred to the award-winning presentation of cases by Radney, who noted that the maxillary incisors are centered in the premaxilla, and that the incisal edges of the mandibular incisors are consistently aligned with line NA, regardless of the jaw relationship. Tom explained that this pattern has been demonstrated by analyzing cases in which the jaw relationships differ considerably from average. As the mandible is positioned farther back relative to the maxilla, the mandibular incisors become more and more protrusive. Conversely, as the mandible is positioned farther and farther forward relative to the maxilla, the mandibular incisors become more and more retrusive. From analyzing many cephalometric tracings Tom agrees with Radney's observation that maxillary incisor positions in the maxilla do not vary as much as mandibular incisor positions on the mandible. Tom stressed that this is exactly opposite to the Tweed and Steiner analyses and somewhat contrary to the Ricketts analysis. The goals of these analyses would retract the teeth too far in the face in high-ANB, high-convexity cases. Extractions could be required to reach the goals, possibly leading to a flattening of the face. On the other hand, the goals for low-ANB, low-convexity cases, would indicate more non-extraction treatment, which can produce too protrusive a result. Creekmore's conclusion on where to position the teeth in the face and jaws is to have the maxillary incisors at 5mm plus/minus 2mm and 22 degrees plus/minus 5 degrees to NA for all skeletal patterns (the measurements increase as the ANB angle decreases and decrease as the ANB increases), and to position the mandibular incisal edges at 0.5mm plus minus 2mm to NA and 25 degrees plus/minus 5 degrees to NB (values decreasing as ANB decreases and increasing as ANB increases). The last topic Creekmore discussed was the question of how to reach our treatment goals. He stressed that the most important thing we do in our offices is the time we spend planning a workable solution to the patient's problem. To achieve these goals he recommended we do a subjective evaluation of the patient's problems during the initial examination followed by a detailed objective evaluation using the patient's records. Tom explained that aligning teeth on their individual arches is easy. The most difficult task is to establish proper overjet and overbite with the jaws in CR. This usually requires good treatment planning, favorable growth, and patient cooperation. Tom suggested that a good way to reduce the need for compliance is by strategic extraction of certain teeth other than four first bicuspids (second bicuspids, cuspids, first molars, etc). This helps develop proper intra-arch anchorage for positioning the teeth on the jaws, and proper inter-arch anchorage to correct the overbite and overjet in CR. Strategic extraction does not entirely eliminate the need for patient cooperation, but greatly reduces it, since it is mechanically easier to obtain a better result by controlling reciprocal anchorage. He does not like to use appliances that reduce the requirement for patient compliance (Herbst, Jasper Jumper, Pendulum, etc) because they may not deliver teeth to the best positions for optimum esthetics and stability. Tom briefly touched on the subject of SWA. He explained that one prescription of SWA does not fit all patients. An individualized prescription is what he advocates. He stressed that when retracting teeth greater torque is needed so that the wires being used are also important, not just the prescription. Tom finished his lecture by showing the treatment he performed on the four difficult clinical cases he presented at the beginning. One of the examples was a skeletal Class III patient who was still in the growth period. He showed that it is best to take records and observe the patient taking serial head-films to be able to superimpose the tracings and observe the magnitude and direction of growth. By not extracting teeth in this type of patient one can keep treatment options open until growth ceases, at which time a definitive treatment plan can be established. Tom's presentation was very interesting because he encouraged audience participation in the diagnosis and treatment planning of the clinical cases he showed.