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Late lower anterior crowding: Growth and orthodontic treatment
84
Am. J. Orthod. Janua~ I983
Reviews and abstracts
compressiveor tensile forces. Prostaglandinsynthesis in this systemrevealeda relative increasein TXB, synthesized after 10 m inutes of force application, with a return to normal after 30 m inutes. This thesis has reported on the development and use of two in vitro techniques which will make possible future study of cellular regulators and behavior during orthodontic tooth movement.
The Effects of Second Molar Extraction in Conjunction With Bionator Treatment M. Toufic Jeiroudi Loma Linda University, 1982
The objective of this study was to evaluate the effects of second molar extractions in conjunction with bionator functional appliancetreatment. Eighteen orthodontic patients were used in this study. All had upper and lower second molars extracted. Lateral cephalometric radiographswere traced and usedto evaluatethe treatment. The averageage at time of extraction was 13 years 3 months. The averagetreatment time was 38.3 months. Some orthodontic changeswere noted. The facial convexity decreasedsignificantly; the condyle axis increasedmore than expected in normal growth. Also, both the lower facial height and the facial axis became more dolichotype (open). The upper and lower incisors were tipped distally. The upper first molar was held back and the lower first molar moved distally up to 5 m m ., with an averageof 1 m m . All third molars erupted into place. The data indicate that if the patient has a slightly dolichofacial axis (less than 90 degrees)and long condyle axis at T, (beginningof treatment), we can expect some significant distal movement of the lower first molar after extraction of the lower second molar, in addition to skeletal orthopedicchangeselicited by conventional biometer therapy.
Three-Dimensional Force and Moment Characteristics of Selected Low-Modulus Arch Wires D. J. Sullivan Orthodontic Section, University of Manifoba, Winnipeg, Manitoba, Canada. I982
As a means of aligning irregular teeth, many orthodontists today are employing some form of a continuous, low-modulus, “flexible ” arch wire. The present
study was undertakento investigatethe forces and moments generatedby implementationof such practice. A measuring instrument developed at the University of Manitoba, capableof simultaneouslymeasuringthreedimensionalforces and moments, was used to generate the data. Use of a m inicomputer provided easy means of data acquisition and analysis. Results were obtained from commonly used wires-O.381 m m . (0.015 inch) Tri-Flex, 0.445 m m . (0.0175 inch) T&Flex, 0.406 m m . (0.016 inch) nitinol and TMA, and 0.47 m m . (0.018 inch) nitinol and TMA-with interbracket distances representativeof those seen clinically. Measurementswere made on a m isaligned model tooth and on the adjacentreactiveteeth. Thus, data were obtained which indicatesthe likely movementof the teeth in the region of m isalignment. The analysisof the results suggestedthat when typical orthodontic geometries were used, unacceptably high forces and moments were generatedby all arch wires examined and, though considered to be lowmodulus “flexible” arch wires, the load-deflection ratesfor each wire were much higher than that which is currently acceptedas ideal. Implementation of a continuous low-modulus arch wire to correct a single m isaligned tooth will likely induce a significant “ripple” effect throughout the arch, once tooth movement is initiated with frictional and “wedging” forces causing undesiredmovementsand rotations of both active and reactive teeth as the arch wires deactivate.
Late Lower Anterior Crowding: Growth and Orthodontic Treatment William A. Raineri, D.D.S. Eastman Dental Center, 1982
A lo-year postretention study was undertaken to investigate the effects of form, treatment, and posttreatment change in orthodontic patients in attempt to identify factors which m ight contribute to late lower anterior crowding. The sampleconsistedof forty-eight patientswho had been treated with the edgewiseappliance and had undergonesome phaseof retention. The sample was divided into four groups on the basis of presenceor absenceof crowding before treatmentand a m inimum of 10 years out of retention. Records included lateral cephalometricheadfilms and study models that had been taken at three intervals of time: pretreatment, retention, and postretention.Each headfilm was subjectedto forty measurementsand comparedto the University of M ichigan growth standards.Change was assessednumerically by the difference betweenthe
Reviews and abstracts
same variables at each time interval. Changewas also assessedby superimposingsuccessiveheadfilms. Finally, all data were analyzedstatistically. Results indicated the following factors to be statistically significant in the groups that developedcrowding after treatment: mandibular retrognathism, proclination of the lower incisor during treatment, greater reduction of skeletal convexity during treatment, greater uprighting of the lower incisor after treatment, and mandibular growth after treatment that was characterizedby upward and forward rotation.
Temporomandibular Joint Morphology as Related to Anterior Occlusion and Vertical Facial Height: A Laminagraphic Study Alfred C. Griffin, Jr. Eastman Dental Center, 1982
‘lhe concept of a mutually protected occlusion identifies two anatomic areas that guide mandibular movement during protrusion. Posteriorly, the condyle closely follows the posterior slope of the articular eminence, referred to as the posterior guidance slope (PCS). Anteriorly, the path of the incisal edge of the mandibularincisor is determinedby the lingual surface of the maxillary incisors, or the anterior guidanceslope (AGS). This study attemptedto evaluatethe relationship betweenthesetwo guidanceslopesof the mandible. Laminagraphsof the temporomandibularjoint were usedto define fossa morphology in thirty-two subjects. The anterior occlusion was evaluatedon lateral cephalometric head films. The correlative comparison between these two areas showed a substantialtendency for subjectswith increasedoverbite to have greaterartitular eminenceheights and a greaterinclination to the posterior guidanceslope. The AGS-PCS relationship of subjects displaying temporomandibularjoint dysfunction was then compared to a control sample that was asymptomaticfor TMJ dysfunction. While the asymptomatic group showed a very strong correlation between the inclinations of AGS and PGS, the dysfunction group showeda slight negative correlation. This lack of harmony be-
85
tween anterior and posterior guidanceduring mandibular excursionsmay be contributory to the temporomandibular joint dysfunction that these subjectsexhibited. When evaluating the position of the maxillary incisors during orthodontic diagnosis and treatment planning, it may prove necessaryto consider also the incisor’s relationshipto the posterior guidanceslope in order to allow for harmoniousmandibular excursions.
Der Einflus herausnehmbarer kieferotthopadlscher Apparate auf den Nachtschlaf der Patienten (Influence of Removable Orthopedic Appliances on Patient Sleep) Franz G. Sander Fortschr. Kieferorthop. 43: 57-63, 1982
Considerablespeculationexists on sleeping habits of orthodontic patients wearing removable appliances, such as retainers, positioners, and functional appliances. Various designs of functional applianceshave been recommendedto offset the effects of repose and still activate the neuromusculature. This extensive study by a highly respectedGerman investigator provides some important answers. Five patients and three controls were studied for forty nights. The patients had already worn their activators for a 6-month period. The EEG telemetry was done in the homes of the subjects to reduce possible extrinsic factor effect. The vertical dimensionwas alteredfrom 4 m m . openingto 16 m m . in the molar region. The sagittal relationship was also increased substantially, and the effects were carefully recorded. The results show that patients already accustomed to their activatorsshow no disturbancein their sleeping patterns, substantiating the 1974 electromyographic study by Lill on patientswearing Bionators. Both vertical and sag&al increase in the construction bite can affect sleeping patterns significantly. The most significant effects were seenwith poorly fitting activators. For patientswearing the activator for the first time, the author advisesthat the changesin the vertical and sagittal dimensionsbe m inimal. T. M. Graber
Am. J. Orthod. Janua~ I983
Reviews and abstracts
compressiveor tensile forces. Prostaglandinsynthesis in this systemrevealeda relative increasein TXB, synthesized after 10 m inutes of force application, with a return to normal after 30 m inutes. This thesis has reported on the development and use of two in vitro techniques which will make possible future study of cellular regulators and behavior during orthodontic tooth movement.
The Effects of Second Molar Extraction in Conjunction With Bionator Treatment M. Toufic Jeiroudi Loma Linda University, 1982
The objective of this study was to evaluate the effects of second molar extractions in conjunction with bionator functional appliancetreatment. Eighteen orthodontic patients were used in this study. All had upper and lower second molars extracted. Lateral cephalometric radiographswere traced and usedto evaluatethe treatment. The averageage at time of extraction was 13 years 3 months. The averagetreatment time was 38.3 months. Some orthodontic changeswere noted. The facial convexity decreasedsignificantly; the condyle axis increasedmore than expected in normal growth. Also, both the lower facial height and the facial axis became more dolichotype (open). The upper and lower incisors were tipped distally. The upper first molar was held back and the lower first molar moved distally up to 5 m m ., with an averageof 1 m m . All third molars erupted into place. The data indicate that if the patient has a slightly dolichofacial axis (less than 90 degrees)and long condyle axis at T, (beginningof treatment), we can expect some significant distal movement of the lower first molar after extraction of the lower second molar, in addition to skeletal orthopedicchangeselicited by conventional biometer therapy.
Three-Dimensional Force and Moment Characteristics of Selected Low-Modulus Arch Wires D. J. Sullivan Orthodontic Section, University of Manifoba, Winnipeg, Manitoba, Canada. I982
As a means of aligning irregular teeth, many orthodontists today are employing some form of a continuous, low-modulus, “flexible ” arch wire. The present
study was undertakento investigatethe forces and moments generatedby implementationof such practice. A measuring instrument developed at the University of Manitoba, capableof simultaneouslymeasuringthreedimensionalforces and moments, was used to generate the data. Use of a m inicomputer provided easy means of data acquisition and analysis. Results were obtained from commonly used wires-O.381 m m . (0.015 inch) Tri-Flex, 0.445 m m . (0.0175 inch) T&Flex, 0.406 m m . (0.016 inch) nitinol and TMA, and 0.47 m m . (0.018 inch) nitinol and TMA-with interbracket distances representativeof those seen clinically. Measurementswere made on a m isaligned model tooth and on the adjacentreactiveteeth. Thus, data were obtained which indicatesthe likely movementof the teeth in the region of m isalignment. The analysisof the results suggestedthat when typical orthodontic geometries were used, unacceptably high forces and moments were generatedby all arch wires examined and, though considered to be lowmodulus “flexible” arch wires, the load-deflection ratesfor each wire were much higher than that which is currently acceptedas ideal. Implementation of a continuous low-modulus arch wire to correct a single m isaligned tooth will likely induce a significant “ripple” effect throughout the arch, once tooth movement is initiated with frictional and “wedging” forces causing undesiredmovementsand rotations of both active and reactive teeth as the arch wires deactivate.
Late Lower Anterior Crowding: Growth and Orthodontic Treatment William A. Raineri, D.D.S. Eastman Dental Center, 1982
A lo-year postretention study was undertaken to investigate the effects of form, treatment, and posttreatment change in orthodontic patients in attempt to identify factors which m ight contribute to late lower anterior crowding. The sampleconsistedof forty-eight patientswho had been treated with the edgewiseappliance and had undergonesome phaseof retention. The sample was divided into four groups on the basis of presenceor absenceof crowding before treatmentand a m inimum of 10 years out of retention. Records included lateral cephalometricheadfilms and study models that had been taken at three intervals of time: pretreatment, retention, and postretention.Each headfilm was subjectedto forty measurementsand comparedto the University of M ichigan growth standards.Change was assessednumerically by the difference betweenthe
Reviews and abstracts
same variables at each time interval. Changewas also assessedby superimposingsuccessiveheadfilms. Finally, all data were analyzedstatistically. Results indicated the following factors to be statistically significant in the groups that developedcrowding after treatment: mandibular retrognathism, proclination of the lower incisor during treatment, greater reduction of skeletal convexity during treatment, greater uprighting of the lower incisor after treatment, and mandibular growth after treatment that was characterizedby upward and forward rotation.
Temporomandibular Joint Morphology as Related to Anterior Occlusion and Vertical Facial Height: A Laminagraphic Study Alfred C. Griffin, Jr. Eastman Dental Center, 1982
‘lhe concept of a mutually protected occlusion identifies two anatomic areas that guide mandibular movement during protrusion. Posteriorly, the condyle closely follows the posterior slope of the articular eminence, referred to as the posterior guidance slope (PCS). Anteriorly, the path of the incisal edge of the mandibularincisor is determinedby the lingual surface of the maxillary incisors, or the anterior guidanceslope (AGS). This study attemptedto evaluatethe relationship betweenthesetwo guidanceslopesof the mandible. Laminagraphsof the temporomandibularjoint were usedto define fossa morphology in thirty-two subjects. The anterior occlusion was evaluatedon lateral cephalometric head films. The correlative comparison between these two areas showed a substantialtendency for subjectswith increasedoverbite to have greaterartitular eminenceheights and a greaterinclination to the posterior guidanceslope. The AGS-PCS relationship of subjects displaying temporomandibularjoint dysfunction was then compared to a control sample that was asymptomaticfor TMJ dysfunction. While the asymptomatic group showed a very strong correlation between the inclinations of AGS and PGS, the dysfunction group showeda slight negative correlation. This lack of harmony be-
85
tween anterior and posterior guidanceduring mandibular excursionsmay be contributory to the temporomandibular joint dysfunction that these subjectsexhibited. When evaluating the position of the maxillary incisors during orthodontic diagnosis and treatment planning, it may prove necessaryto consider also the incisor’s relationshipto the posterior guidanceslope in order to allow for harmoniousmandibular excursions.
Der Einflus herausnehmbarer kieferotthopadlscher Apparate auf den Nachtschlaf der Patienten (Influence of Removable Orthopedic Appliances on Patient Sleep) Franz G. Sander Fortschr. Kieferorthop. 43: 57-63, 1982
Considerablespeculationexists on sleeping habits of orthodontic patients wearing removable appliances, such as retainers, positioners, and functional appliances. Various designs of functional applianceshave been recommendedto offset the effects of repose and still activate the neuromusculature. This extensive study by a highly respectedGerman investigator provides some important answers. Five patients and three controls were studied for forty nights. The patients had already worn their activators for a 6-month period. The EEG telemetry was done in the homes of the subjects to reduce possible extrinsic factor effect. The vertical dimensionwas alteredfrom 4 m m . openingto 16 m m . in the molar region. The sagittal relationship was also increased substantially, and the effects were carefully recorded. The results show that patients already accustomed to their activatorsshow no disturbancein their sleeping patterns, substantiating the 1974 electromyographic study by Lill on patientswearing Bionators. Both vertical and sag&al increase in the construction bite can affect sleeping patterns significantly. The most significant effects were seenwith poorly fitting activators. For patientswearing the activator for the first time, the author advisesthat the changesin the vertical and sagittal dimensionsbe m inimal. T. M. Graber