1. Treat to ideal standards of perfection obtaining the Little RM,Wallen T, Riedel R: Stability and relapse of mandibular best possible occlusion, oral health, and function. anterior alignment. First premolar extraction cases treated by 2. Avoid expansion of the lower arch unless man- traditional edgewise orthodontics. Am J Orthod 80:349-65, 1981. dated by facial profile concerns or to harmonize Little R, Riedel R, Artun J: An evaluation of changes in dentitions the occlusion with maxillary palatal expansion ac- during a ten to twenty year postretention period. AmJ Orthod, complished for crossbite correction or unusual nar- in press. rowness. Little R, Riedel R, Engst D: Stability and relapse of mandibular 3. anterior alignment. Serial extraction cases treated by tradi- Use the patient’s pretreatment arch form as a guide tional edgewise orthodontics. Am] Orthod, in press. to arch shape. Little R, Riedel R, Stein A: Increasing mandibular arch length in 4. Retain the arch form long-term and continue to the mixed dentition. A postretention investigation. AmJ Or- monitor patient response into and through adult thod, in press. life. Little R, Riedel R: Mandibular arch spacing--a postretention study 5. Obtain the highest quality pre- and posttreatment of stability and relapse. AmJ Orthod, in press. Shields T, Little RM,Chapko M: Stability and relapse of mandibular records and continue to utilize them to assess pa- anterior alignment: a cephalometric appraisal of first-premo- tient progress. lar-extraction cases treated by traditional edgewise orthodon- tics. AmJ Orthod 87:27-38, 1985. Gilmore C, Little RM: Mandibular incisor dimensions and crowd- Sinclair P, Little RM: Maturation of untreated normal occlusions. ing. AmJ Orthod 86:493-502, 1984. Am J Orthod 83:114-23, 1983. An evaluation of the criteria used to determine arch perimeter problems Study Group 1" The dynamics of transition from primary to pediatric dentist in evaluating arch perimeter prob- permanent dentition requires the pediatric dentist to lems, was arch length analysis. This falls into two constantly evaluate the changing dental space re- major categories: (1) the direct analysis; and (2) quirements of the growing child. Numerous criteria regression analysis. The direct analysis utilizes ra- have been proposed to aid in this evaluation process. diographs and enlargement factors to obtain an ac- It was the assignment of this workshop to examine curate measurement of the developing canines and and evaluate each of these criteria. premolars. The Hixon-Oldfather and modified The first criterion examined by this workshop, Hixon-Oldfather analyses have been shown to most and perhaps the most commonly used tool by the accurately predict arch length requirements. The regression analyses are based on tooth sizes of erupt- * WorkshopLeader: Gary J. Dilley. Participants: Gerald R. Aaron, ed teeth (i.e., permanent incisors) and then regressed Kurt Bomze, Eldon L. Bunn, Stephen L. Fehrman, Bruce E. Golden, to the correlation between the mesiodistal dimen- David L. Good, John N. Groper, Stanley C. Herman, Joseph P. sions of the canines and premolars. While these anal- O’Donnell, David D. Offutt, David R. Oliver, Melvin N. Oppen- heim, David E. Paquette, Robert L. Roebuck, and Joseph L. Sigala. yses are somewhat less accurate, they offer the ad- Editor: Andrew Sonis. vantage of an easy, rapid assessment of arch length 70 SPECIAL REPORT requirements without need for radiographs. In the In summary, the pediatric dentist must consider mixed dentition accuracy to within 3 mmseems more numerous criteria in evaluating arch perimeter prob- than adequate as borderline cases will probably be lems. While many of these criteria have a good sci- treated initially by the nonextraction method. Most entific basis, others tend to be more empiric in nature. participants felt these regression analyses were ade- Consequently, the dentition of the growing child re- quate. quires constant monitoring and reassessment. Treat- The second criterion discussed was the Bolton ment decisions may require modification to accom- analysis of tooth size discrepancies. Since this anal- modate any changes observed. ysis relies on the mesiodistal dimensions of the per- manent maxillary and mandibular 6 anterior teeth or Conclusions all permanent incisors, canines, premolars, and first 1. Arch length analyses that are accurate within 3 molars, it was felt to have limited value in the mixed mmare considered adequate for evaluation of arch dentition. However, the Bolton analysis should be perimeter problems in the mixed dentition. useful for correction of discrepancies in the full per- 2. Facial profile of the child is of primary importance manent dentition addressed by the pediatric dentist. in the management of arch perimeter problems. Perhaps the most important diagnostic criterion Consideration must be given to future nose and was consideration of facial profile. It was felt that chin growth. minor crowding, relapse, and some periodontal con- 3. The effect of habits on arch perimeter problems is cerns play secondary roles to obtaining a good profile. not well understood and requires additional study. Profile evaluation should include consideration of 4. Leveling the Curve of Spee consumes arch length not only the lower face, but also future growth of the and thus must be considered a factor in arch pe- nose and chin. In addition, racial, ethnic, and familial rimeter management. characteristics must influence the desired treatment objectives. Bolton WA:Disharmony in tooth size and its relation to the analysis Arch perimeter problems also may be compound- and treatment of malocclusion. AmJ Orthod 28:113-30, 1958. Bowden BD: The effects of digital and dummysucking on arch ed by early loss of over-retained primary teeth and widths, overbite, and overjet: a longitudinal study. Aust Dent by eruption patterns of permanent teeth. Ankylosed J 11:396-404, 1966. primary teeth may act as excellent space maintainers, Garcia R: Leveling the Curve of Spee: a new prediction formula. but they must be monitored to prevent adverse se- J Chas H Tweed Int’l Found 65-72, 1985. quelae, such as mesial tipping of first permanent mo- Gardner RB: A comparison of four methods of predicting arch length. AmJ Orthod 75:387-98, 1979. lars, supra-eruption of the opposing teeth, or retard- Harris EF, Smith RJ: Occlusion and arch size in families. Angle ing the eruption of underlying succedaneous teeth. Orthod 52:135-43, 1982. The effects of various habits on arch perimeter Kurol J, Koch G: The effect of extraction of infra-occluded decid- problems have not been studied adequately to pro- uous molars: a longitudinal study. AmJ Orthod 87:46-55, 1985. vide any definitive conclusions. Likewise, while arch Magnusson TE: The effect of premature loss of deciduous teeth on the spacing of the permanent dentition. Eur J Orthod 1:213- forms are well related to facial types, their influence 19, 1979. on arch perimeter is not well known. It is felt that Proffit WR, Chastain BG, Norton LA: Linguopalatal pressure in all preformed arch wires should be individualized to children. AmJ Orthod 55:154-66, 1969. prevent the unwanted arch expansion which may Sanin C, Savara BS: Factors that effect the alignment of the man- contribute to relapse. dibular incisors: a longitudinal study. AmJ Orthod 64:248-57, 1973. Leveling the Curve of Spee may contribute to Sanin C, Savara BS, Clarkson QC, Thomas DR: Predictions of oc- arch perimeter problems as this procedure consumes clusion by measurements of the deciduous dentition. Am J arch length. Conversely, a deepening of the curve by Orthod 57:561-72, 1976. allowing supra-eruption of the mandibular incisors Staley RN, Hu P, Hoag JF, Shelby TH: Prediction of the combined in primary canine extraction cases should be avoided right and left canine and premolar widths in both arches of the mixed dentition. Pediatr Dent 5:57-60, 1983. through the judicial use of appliances such as lingual arch. PEDIATRICDENTISTRY: March 1987/Vol. 9 No. 1 71 The value of leeway space and its management Study Group 2* The term "leeway space," first used by Dr. Hays (second); therefore, the term needs to be defined N. Nance (1947), refers to the difference between the clearly or eliminated. Workshop participants consid- total mesiodistal dimension of the primary canine, ered a new definition of serial extraction: "The se- first and second molars, and the permanent canine, lective removal of primary teeth to facilitate eruption first and second premolars. This excess space can be and resolve crowding of the permanent dentition, not maintained and utilized to relieve some or all of an necessarily resulting in the extraction of permanent arch length discrepancy which is initially evident teeth." The term "serial eruption" or "sequential space with the eruption of the permanent anterior teeth management" might better describe this early occlu- during the early mixed dentition. This workshop ex- sal therapy than "serial extraction." plored the value of the leeway space, when and how When the primary mandibular canines are ex- to utilize it, and, most importantly, how to integrate tracted, placement of a mandibular lingual holding it into a total plan for managing an arch length dis- arch may be indicated. In Class II division II maloc- crepancy. clusions, deep bites, cases with hypertonic muscula- Pediatric dentists often observe crowding in the ture, and/or poor facial profile, the use of a lingual anterior region during the early mixed dentition stage. holding arch is recommended strongly in order to This early crowding of the permanent dentition can prevent lingual tipping of the incisors. This "lingual cause or be associated with periodontal problems such collapse" will decrease arch length, increase the over- as soft tissue dehiscences or, in more extreme ex- bite, and often worsen the profile. In other maloc- amples, bony defects when crowding forces teeth off clusions associated with crowding and early extrac- the bony base.