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Safety and Efficiency of Invisalign in Mixed Dentition

Permanent Link: http://ufdc.ufl.edu/UFE0024660/00001

Material Information

Title: Safety and Efficiency of Invisalign in Mixed Dentition
Physical Description: 1 online resource (28 p.)
Language: english
Creator: Long, Brion
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2009

Subjects

Subjects / Keywords: crossbite, crowding, deepbite, invisalign, mixed, quality, spacing
Dentistry -- Dissertations, Academic -- UF
Genre: Dental Sciences thesis, M.S.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: ABSTRACT Objective: To evaluate the safety and effectiveness of treatment with Invisalign in patients possessing mixed dentition who present with any combination of anterior crossbite, posterior crossbite, malalignment (crowding), spacing, and deep bite. Materials and Methods: A multi-site clinical trial enrolled a total of 100 patients. Data were collected at baseline and 6 week intervals up to 24 weeks. Incisor alignment was measured using a modified Little?s Index at baseline, week 12, and week 24. Deep bite and crossbite correction, gingival inflammation index (GI), plaque index (PI), decalcification index (DI), and quality of life surveys were recorded. Results: A 35% reduction in the Little Index score on the upper arch and a 36% reduction on the lower arch from week 0 to week 24 occurred in subjects with malalignment. In subjects with spacing, a 59% reduction in the upper arch was observed. By week 24, 58% of the patients with anterior crossbites were corrected. In comparison, 50% of the patients with posterior crossbites were corrected. Mean bite depth improved 12%. No significant changes in GI, PI, or DI were observed. At week 24, 97% of patients experienced no impediment to speech, 98% showed no inhibition to eating, and 95% reported no need to take pain medication to ease discomfort. Conclusion: Invisalign offers an esthetic modality to correct certain malocclusions in the mixed dentition
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility: by Brion Long.
Thesis: Thesis (M.S.)--University of Florida, 2009.
Local: Adviser: Wheeler, Timothy T.

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2009
System ID: UFE0024660:00001

Permanent Link: http://ufdc.ufl.edu/UFE0024660/00001

Material Information

Title: Safety and Efficiency of Invisalign in Mixed Dentition
Physical Description: 1 online resource (28 p.)
Language: english
Creator: Long, Brion
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2009

Subjects

Subjects / Keywords: crossbite, crowding, deepbite, invisalign, mixed, quality, spacing
Dentistry -- Dissertations, Academic -- UF
Genre: Dental Sciences thesis, M.S.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: ABSTRACT Objective: To evaluate the safety and effectiveness of treatment with Invisalign in patients possessing mixed dentition who present with any combination of anterior crossbite, posterior crossbite, malalignment (crowding), spacing, and deep bite. Materials and Methods: A multi-site clinical trial enrolled a total of 100 patients. Data were collected at baseline and 6 week intervals up to 24 weeks. Incisor alignment was measured using a modified Little?s Index at baseline, week 12, and week 24. Deep bite and crossbite correction, gingival inflammation index (GI), plaque index (PI), decalcification index (DI), and quality of life surveys were recorded. Results: A 35% reduction in the Little Index score on the upper arch and a 36% reduction on the lower arch from week 0 to week 24 occurred in subjects with malalignment. In subjects with spacing, a 59% reduction in the upper arch was observed. By week 24, 58% of the patients with anterior crossbites were corrected. In comparison, 50% of the patients with posterior crossbites were corrected. Mean bite depth improved 12%. No significant changes in GI, PI, or DI were observed. At week 24, 97% of patients experienced no impediment to speech, 98% showed no inhibition to eating, and 95% reported no need to take pain medication to ease discomfort. Conclusion: Invisalign offers an esthetic modality to correct certain malocclusions in the mixed dentition
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility: by Brion Long.
Thesis: Thesis (M.S.)--University of Florida, 2009.
Local: Adviser: Wheeler, Timothy T.

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2009
System ID: UFE0024660:00001


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1 SAFETY AND EFFICIENCY OF INVISALIGN IN MIXED DENTITION By BRION T. LONG A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2009

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2 2009 Brion T. Long

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3 ACKNOWLEDGMENTS I would like to thank God for giving me the opportunity to do research and my family for their unwavering support.

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4 TABLE OF CONTENTS page ACKNOWLEDGMENTS .................................................................................................................... 3 LIST OF TABLES ................................................................................................................................ 5 LIST OF FIGURES .............................................................................................................................. 6 ABSTRACT .......................................................................................................................................... 7 CHAPTER 1 INTRODUCTION ......................................................................................................................... 9 2 MATERIALS AND METHODS ............................................................................................... 11 3 RESULT S .................................................................................................................................... 14 4 DISCUSSION .............................................................................................................................. 20 5 CONCLUSIONS ......................................................................................................................... 24 REFERENCES ................................................................................................................................... 25 BIOGRAPHICAL SKETCH ............................................................................................................. 28

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5 LIST OF TABLES Table page 3 1 PI GI, and DI mean scores at week 0 and week 24 with associated standard error and P values. P values calculated with paired t test (N=80). ...................................................... 16 3 2 Anterior and posterior crossbite correction with 95% confidence intervals for patients +/5 weeks of designated time point ...................................................................... 16 3 3 Mean bite depth for patients with deep bite and those without measured within 5 weeks of time point. ............................................................................................................... 16 3 4 Change in bite depth between time points. P value calculated with paired t -tests using mean change between time points. ........................................................................... 17 3 5 Mean Modified Littles Index values (mm) for different combinations of crowding/spacing with associated standard errors at week 0 (T1), week 12 (T2), and we ek 24 (T3). P values calculated using paired t test. ........................................................ 17 3 6 Mean percentage change between week 0 -week 12 (T0T1), week 12 -week 24 (T1 T2), and week 0 -week 24 (T1T2). Number (N) of patients in category next to percentage. .............................................................................................................................. 17 3 7 P values between weeks for prob lems talking with aligners, eating with aligners, pain due to aligners, and pain resulting in medication usage. ............................................. 18

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6 LIST OF FIGURES Figure page 3 1 Malocclusion Categories with number of participants. Subjects can have more than one malocclusion type. ........................................................................................................... 18 3 2 Treatment site locations and number of participants. .......................................................... 18 3 3 Percentage of subjects reporting pain with aligner use, having pain requiring medication usage for pain relief, problems talking due to aligners, and problems eating due to aligners. ............................................................................................................ 19

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7 Abstract of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science SAFETY AND EFFICIENCY OF INVISALIGN IN MIXED DENTITION By Brion T. Long August 2009 Chair: Timothy Wheeler DMD, PhD Major: Dental Science s Objective : T o evaluate the safety and effectiveness of treatment with Invisalign in patients possessing mixed dent ition who present with any combination of anterior crossbite, posterior crossbite, malalignment (crowding), spacing, and deep bite. Materials and Methods : A multi -site clinical trial enrolled a total of 100 patients. Data were collected at baseline and 6 week intervals up to 24 weeks. Incisor alignment was measured using a modified Littles Index at baseline, week 12, and week 24. Deep bite and crossbite correction, gingival i nflammation index (GI), plaque index (PI), decalcifi cation index (DI), and quality of life surveys were recorded. Results: A 35% reduction in the Little Index score on the upper arch and a 36% reduction on the lower arch from week 0 to week 24 occurred in subjects with malalignment. In subjects with spacing, a 59% reduction in the upper arch was observed. By week 24, 5 8 % of the patients with anterior crossbite s were corrected In comparison, 50% of the patients with posterior crossbites were co rrected. Mean bite depth improved 12 %. N o significant changes in GI, PI, or DI were observed. At week 24, 97% of patients experienced no impediment to speech, 98% showed no inhibition to eating, and 95% reported no need to take pain medication to ease disc omfort.

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8 Conclusion : Invisa lign offers an esthetic modality to correct certain malocclusions in the mixed dentition

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9 CHAPTER 1 INTRODUCTION The l ate 1990s brought the advent of an orthodontic treatment modality that appeared to offer an esthetic alternative to traditional braces.1 Manufactured by Align Technology, Inc., this treatment methodology consists of a sequenced application of clear polyure thane aligners that is promoted as an invisible way to straighten teeth. 2 At the o n set of Aligns marketing program in 1999, the U.S. Food and Drug Administration (FDA) imposed a labeling requirement which contraindicated the Invisalign system for patients with unerupted second molars. But in December 2008, the FDA relaxed that restriction, th us enabling Align Technology to market its newly introduced Invisalign Teen product line to a younger demographic .3 Although the Invis align system was not approved for patients with mixed dentition prior to 2009, the utilization of removable orthodontic appliances in children is not a new concept. In research conducted by Littlewood et al,4 it was found that removable appliances have some advantage over co nventional fixed appliances when used correctly to treat patients with mixed dentition. In particular, Littlewood opines that removable appliances can: (1) provide increased vertical an d horizontal anchorage in the mixed dentition due to palatal coverage; (2) produce efficient overbite reduction in patients who are still experiencing dental and skeletal growth; (3) transmit forces to blocks of teeth; and (4) enable the patient to sustain hygienic cleanliness because they are removable.4 Several studies in adults have reported on the effectiveness of aligner movement .57 All of these studies focused either on aligner material8 or the ability of moving adult teeth without further practitioner intervention other than delivering aligners.7 In a 2007 case repor t involving three patients, Boyd9 deemed Invisalign as capable of effecting successful corrections of

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10 moderate crowding, deep bites, and moderate Class II division 1 malocclusions, provided the patient complies with a minimum aligner usage of 22 hours per day. Any appliance used to correct malocclusions may impact the quality of life of the patient. In a cohort study involving 217 children who receiv ed fixed orthodontic applianc e therapy Zhang et al10 found that there was a significant deterioration in ov erall quality of life during treatment compared with pretreatment at one week and one month time intervals. Serg l et al11 reported in a sample of 84 patients that severity of pain and discomfort experienced by the patients wearing fixed appliances w as significantly higher than those treated with upper and/or lower removable appliances. In a multi -site trial examining quality of life and pain during the first week of treatment in adult patients with either fixed appliances or Invisalign Miller et al12 observed that Invisalign patients reported fewer negative impacts on overall quality of life and exper ienced less pain. The purpose of this study was to evaluate the safety and effectiveness of treatment with Invisalign aligners in patients with mixed dentition who present with one or more of the following occlusion problems : (1) anterior crossbite; (2) p osterior crossbite; (3) malalignment (crowding ); (4) space closure; and (5) deep bite.

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11 CHAPTER 2 MATERIALS AND METHOD S A goal of 100 subjects was slated for inclusion in this study. This number was based on a minimum of 20 participants in each malocclusion group (deep bite, anterior crossbite, posterior crossbite, crowding, and spacing). Inclusion criteria required the par tic ipants to: (1) be not less than 7 nor more than 12 years of age; (2) be in good health; (3) have at least 4 permanent molars fully erupted; (4) have all 4 incisors; (5) have either a n anterior crossbite, malalignment (crowding) posterior crossbite, spa cing malocclusion, or deep overbite, or any combination thereof; (6) not have a malocclusion needing another appliance; and (7) be willing and able to comply with all procedures throughout the 24 -week duration of the study. Exclusion criteria consisted of the patient having: (1) significant p eriodontal problems; (2) active caries; (3) a severe Class III malocclusion that nece ssitates surgical correction; (4) a chronic daily use of any nonsteroidal anti inflammatory or steroid medication; (5) used any invest igational product within 4 weeks of the onset of the study; and (6) a medical condition that might cause, or exacerbate, a health risk as a result of participation in the study. Children who did not possess a full complement of te eth in the anterior segmen t were excluded as participants. During the initial screening five northern Florida treatment sites, including the University of Florida, were utilized. M odels from each treatment site were sent to the University of Florida for examination so as to ensure all participants fully complied with the inclusion criteria. Alginate impressions were taken and thereafter poured into stone models which, in turn, were subsequently utilized by Align Technology to fabricate the patients polyurethane aligners. All patien ts were treatment planned and Clinchecks approved by a single practitioner (T.T.W.) Patients were seen at 6 -week intervals to receive delivery of the next series of Invisalign aligners,

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12 at which juncture additional study data were captured. The study coo rdinator supervised the aligner delivery and the data collection appointments at each treatment site. The first appointment (week 0) included an intraoral clinical examination to assess, by means of visual inspection, the participants tissue health and gingival recession. The first three a ligners were delivered to the participants with instructions to wear each aligner for a period of 2 weeks before changing to the next aligner. Three additional ali gners were subsequently delivered at 6 -week intervals throughout the 24 -week study period. Study m odels of the upper and lower anterior teeth taken at weeks 0, 12, and 24 were scored with a modified Littles Index by one investigator (B.T.L.), who was tra ined and calibrated in this Index. Digital calipers were used to measure displacement of contact points, starting with the mesial of the lateral incisor and ending at the mesial of the contralateral lateral incisor. A modified Littles Index was utilized b ecause a large number of subjects in this age gr oup had primary canines that were exfoliating during the 24 -week study period, thereby confounding the data Anterior and posterior crossbites were scored as either corrected (+) or not corrected ( ) by the s ame trained and calibrated investigator (B.T.L.). A crossbite was deemed corrected when the affected tooth (teeth) repositioned into the appropriate buccal/lingual orientation when the casts were fully articulated. Improvement in bite depth was measured as a vertical improvement in bite depth of the upper incisor relative to the lower incisal edge. Change in the bite depth was measured from the same teeth that were fully erupted at weeks 12 and 24. The upper incisal edge was marked on the lower incisor when the casts were fully articulated. Digital calipers were used to measure the distance from the line to the incisal edge to the nearest 0.1 mm.

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13 Photographs and impressions for the study models were taken at the beginning of the study, at week 12, and at we ek 24 or earlier if the problem was corrected prior to week 24 Qualitative survey assessments concerning the participants quality of life perceptions were taken at weeks 6, 12, 18, and 24. The participants were asked to report any difficulties experie nced while eating or talking; pain from aligner wear; or instances of pain caused by aligner wear that required analgesic medication. Questions were adapted from a previous questionnaire 12 that examined quality of life in adults. The Plaque Index was ass essed using the Turesky modification of the Quigley-Hein Plaque Index (PI) .13 The Gingivitis Index (GI) was assessed at each visit using th e Papillary Bleeding Score of Loesche .14 The Decalcification Index (DI) was assessed visually and tactilely with a de ntal explorer and scored by using a modified version of the white spot lesion index of Gorelick et al.15 All assessments were made by the same examiner (J.C.) The paired t test was utilized to compare changes in PI, GI, and DI from week 0 to week 24. The paired t test was also used to compare groups for deep bite and modified Littles Index. The Wilcoxon rank sum test was used to compare ages, malocclusion categories, and correction of anterior and posterior crossbites. McNemars test with continuity correction was used to calculate significance for changes in the quality of life variables over time.

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14 CHAPTER 3 RESULTS A total of 100 participants with mixed dentition participated in the study. The participants were comprised of 47 females and 53 males all of whom had any combination of occlusal problems which included anterior crossbite, upper and/or lower crowding (malalignment) posterior crossbite, upper and/or lower anterior spacing, and deep overbite (Fig 3 1.) The mean age of the 100 participant s was 9.5 years, with a racial composition of 85 whites, 10 Hispanics, 4 blacks, and 1 mixed race. Five northern Florida treatment sites were utilized, including the University of Fl orida (UF), Gainesville (GV), Ocala (OC), Orange Park, and Jacksonville ( JX) (Fig 3 2) The Institutional Review Board of the University of Florida approved the stud y, and informed consent was obtained from all participants. The intraoral health of subjects were assessed by means of a plaque index, gingival index, and decalcifi cation index As shown in Table 3 1, there were no statistical differences (p>.05) between week 0 and week 24. Table 3 2 depicts both the percentage and the number of patients with anter ior and posterior crossbites that corrected by either week 12 or week 24. By week 24, 15 patients (5 7.7 %) with anterior crossbites were corrected. In comparison, 11 patients ( 50.0 %) with posterior crossbites were corrected during this same time span Wilcoxan rank sum tests were used to test for differences between the ag es of subjects or the total number of occlusal problems for those subjects whose crossbites were either corrected or not corrected. No significant differences were found between the groups (p>.05). Table 3 3 describes the subject population with and with out deep bite. In the deep bite group, there was a 10.8% change by week 12, and a 12.6% change by week 24. (Table 3 4).

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15 Table 3 5 shows the mean Littles Index values for all patients with spacing and crowding ( malalignment ) in both the upper or lower jaws and associated p -values. Malalignment is defined in this study as being inclusive of crowding, yet additionally contains those patients whose teeth were poorly aligned but did not necessarily have crowding. Subjects with crowdi ng showed a 35.5% reduction in the Littles Index score on the upper arch and a 35.8% reduction on the lower arch from week 0 to week 24. In subjects with spacing, a 58.6% reduction in the upper arch was observed. The lower arch also had a reduction in va lues, but did not meet a level of significant change (p>.05). (Table 3 6) As a means of measuring the impact on the quality of life subjects were given questionnaires at 6 week intervals. The percentage reporting problems talking decreased from 13% (13 out of 97) at week 6 to 3% (3 out of 89) at week 24. A similar percentage decrease was observed in those subjects having problems eating, being reduced from 8% (8 out of 97) to 1 % (1 out of 89). The percentage of participants who reported pain with aligner use was 46% (45 out of 97) at week 6, which thereafter dropped to 21% (19 out of 89) by week 24. For those subjects who required analgesic medication to relieve their pain, 30% (29 out of 97) required medication at week 6, dropping significantly to 4% (4 out of 89) by week 24. (Fig 33 ) P values calculated from McNemars test with continuity correction showed significant changes (P<.05) from week 6 to week 12 fo r subjects reporting problems talking, pain and medication usage for pain. There was also a sig nificant change in medication usage f rom week 12 to week 18 (Table 3 7 )

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16 Table 3 1. PI GI, and DI mean scores at week 0 and week 24 with associated standard error and P values. P values calculated with paired t test (N=80). Variable Week 0 (T0) Week 24 (T2) Mean Change(T0 T2) P value PI upper 0.992(SE .0761) 1.057(SE .0902) 0.0656 0.57 PI lower 0.886(SE .0848) 0.787(SE .0859) 0.0993 0.40 GI upper 1.332(SE .0420) 1.310(SE .0420) 0.0218 0.69 GI lower 1.379(SE .0431) 1.306 (SE .0414) 0.0732 0.17 DI upper 0.031(SE .0117) 0.0139(SE .0047) 0.0172 0.17 DI lower 0.007(SE .0040) 0.005(SE .0031) 0.0020 0.70 Table 3 2. Anterior and posterior crossbite correction with 95% confidence intervals for patients +/ 5 weeks of designated time point Anterior and Posterior Crossbite Correction within 5 weeks of time point Corrected/ Total % Corrected 95% Confidence Interval Anterior Crossbite Week 12 5 of 29 17.20% (5.8% 35.8%) Week 24 15 of 26 57.70% (36.9% 76.6%) Posterior Crossbite Week 12 2 of 23 8.70% (1.1% 28.0%) Week 24 11 of 22 50.00% (28.2% 71.8%) Table 3 3. Mean bite depth for patients with deep bite and those without measured within 5 weeks of time point. Mean Bite Depth (mm) W/O deep bite W Deep bite N Mean Std error N Mean Std error Week 0 57 1.62 0.203 43 4.7 0.159 Week 12 54 1.66 0.208 40 4.18 0.168 Week 24 52 1.89 0.161 35 4.05 0.195

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17 Table 3 4. Change in bite depth between time points. P value calculated with paired t tests using mean change between time points Deep bite change in subjects with Deep Bite within 5 weeks of time point Time Period Mean change (mm) % change P value 0 to 12 weeks 0.561 10.80% 0.0003 12 to 24 weeks 0.08 2.18% 0.062 0 to 24 weeks 0.634 12.62 0.0005 Table 3 5 Mean Modified Littles Index values (mm) for different combinations of crowding/spacing with associated standard errors at week 0 (T1), week 12 (T2), and week 24 (T3). P values calculated using paired t test. T0 T1 T2 P value(T0 T1) P value (T1 T2) P value (T0 T2) Upper Crowding/Spacing 6.26 (SE 0.365) 4.43 (SE 0.302) 3.02 (SE 0.234) <.0001 <.0001 <.0001 Upper crowding 6.22 (SE 0.454) 4.60 (SE 0.388) 3.16 (SE 0.285) <.0001 <.0003 <.0001 Upper spacing 6.41 (SE 0.553) 4.05 (SE 0.404) 2.68 (SE 0.381) <.0001 <.0001 <.0001 Lower Crowding/Spacing 3.15 (SE 0.164) 2.40 (SE 0.137) 1.91 (SE 0.147) <.0001 <.0001 <.0001 Lower Crowding 3.22 (SE 0.169) 2.44 (SE 0.136) 1.99 (SE 0.150) <.0001 <.0001 <.0001 Lower Spacing 1.99 (SE 0.512) 0.78 (SE 0.394) 0.61 (SE 0.288) 0.17 0.58 0.13 Table 3 6. Mean percentage change between week 0 -week 12 (T0T1), week 12week 24 (T1T2), and week 0 -week 24 (T1T2). Number (N) of patients in category next to percentage. Change(T0 T1) Change(T1 T2) Change(T0 T2) Upper Crowding/Spacing 28.1% (N=77) 13.4% (N=77) 42.1% (N=73) Upper crowding 25.7% (N=55) 9.9% (N=49) 35.5% (N=52) Upper spacing 34.3% (N=23) 22.0% (N=22) 58.6% (N=22) Lower Crowding/Spacing 18.0% (N=74) 14.9% (N=66) 37.2% (N=68) Lower Crowding 16.0% (N=70) 15.3% (N=62) 35.8% (N=64) Lower Spacing 52.5% (N=4) 8.6% (N=4) 61.2% (N=4)

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18 Table 3 7. P values between weeks for problems talking with aligners, eating with aligners, pain due to aligners, and pain resulting in medication usage. P values from McNemar's test with continuity correction Talking Eating Pain Medication Wk 6 to 12 0.0055 1 0.0003 0.008 Wk 12 to 18 1 0.07 1 0.0265 Wk 18 to 24 1 1 0.8 1 Figure 3 1 Malocclusion Categories with number of participants. Subjects can have more than one malocclusion type. Figure 3 2 Treatment site locations and number of participants. 29 24 43 60 25 Anterior Crossbite Posterior Crossbite Deep Bite Crowding Spacing Number of participants 51 24 4 10 11 UF GV OC OP JX Number of participants

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19 Figure 3 3. Percentage of subjects reporting pain with aligner use, having pain requiring medication usage for pain relief problems talking due to aligners, and problems eating due to aligners. 13% 8% 46% 30% 2% 7% 21% 15% 2% 1% 23% 6% 3% 1% 21% 4% Talking Eating Pain Medication Week 6 Week 12 Week 18 Week 24

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20 CHAPTER 4 DISCUSSION No previous studies have been undertaken on the use of Invisalign therapy in patients in the mixed dentition. The purpose of this study was to evaluate the effectiveness of treatment with Invisalign aligners in patients with mixed dentition vis vis those malocclusions that are most prevalent in this age group. Plaque Index scores in this study [ upper 1.057 (SE .0902), lower 0.787 (SE .0859) at week 24] were less than those reported elsewhere in the literature,16 while Gingival Inflammation scor es [1.310 (SE.0420) upper, 1.306 (SE .0414) lower at week 24], and DI scores [0.0139 (SE .0047) upper and .002 (SE.0031) lower at week 24] were in the range of scores reported by patients who did not have appliances.1516 The low plaque index scores might correlate to a shorter observation period, or perhaps to a keener group of subjects devoted to oral hygiene than participants involved in other research. Previous studies by Naranjo et al17 and Lee et al18 have established the increased prevalence of plaque after placement of fixed orthodontic appliances. In our study there were n o significant differences for plaque index (PI), papillary bleeding score (GI), and decalcification index (DI) between the values obtained at week 0 and later at week 24 for e ither the upper or the lower a rch This is significant inasmuch it has been reported in the literature that white spot lesions can be seen in 50% of the patients on at least one tooth after treatment with fixed appliances.15 Oral hygiene maintenance appear s to be easier to obtain in the Invisalign system, possibly due to the removable nature of the appliance, which allows for easier access during plaque removal.19 A dearth of quality studies regarding correction of posterior crossbite exists in the literature.2021 Previous studies have reported self correction of posterior crossbites in the mixed dentition to be as high as 45% (9 out of 20 patients)22 to as low as no self correction (0 out of

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21 15).23 Nonetheless, orthodontic correction of crossbites is widely utilized. McNally et al reported correction of posterior crossbite by intermolar expansion using either a quadhelix or expansion arch at 12 weeks with a mean expansion of 4.54 mm and 5.09 mm, respectively, at the molars. Petrn et al23 reported an ave rage treatment time of 4.8 months to correct posterior crossbite u sing a quadhelix. Kennedy et al24 estimates the time to correct a posterior crossbite to be between two to six weeks. In this study, correction of anterior and posterior crossbites at week 24 was 57.7% (95% CI (36.9%76.6%) and 50% (95% CI (28.2%71.8%), respectively. It should be noted that a few patients were not finished with their prescribed number of aligners by the week 24 benchmark. As a result, the correction effectiveness likely wo uld increase if the patients were followed out over a longer period for further observation. Moreover, it would appear that, relative to other studies, the mean time to correct a crossbite is longer using the Invisalign appliance versus more conventional a ppliances, such as the quadhelix.25 E vi dence -based guidance regarding deep bite correction in children is lacking in the literature.26 In this study, b ite depth correction showed a mean improvement of only 13% at the conclusion of week 24. It appears bite depth correction with Invisalign in the mixed dentition patient is an unpredictable movement. These values are in agreement with Kravitz ,7 who found that only 43% of projected anterior intrusion was achieved. This study suggests that significant correctio n of deep overbites with polyurethane aligners is a more difficult movement to achieve. In the transitional dentition, factors such as short crown height erupting permanent teeth, and missing or loose deciduous teeth all contribute to the problem of placi ng the correct biomechanical force to intrude the incisors. This is a problem clinicians encounter with any appliance in the transitional dentition.

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22 Alignment of the dentition in adult patients treated with Invisalign was reported by Kuncio5 to have comparable alignment scores to traditional braces. In this study subjects with crowding showed a 35.5% reduction in the Littles Index score on the upper arch and a 35.8% reduction on the lower arch from week 0 to week 24. In subjects with spacing, a 58.6% reduction in the upper and 61.2% reduction in the lower arch was observed. The low number of subjects categorized as having spacing on the lower arch no doubt contributed to this value lacking statistical significance. Nonetheless, improvement wa s noted in both arches, with reduction of the Littles Index score greater in the spacing subjects. Patients may have experienced even greater reduction in the Littles Index score beyond week 24. Thus it appears the Invisalign System can e ffect improvemen t in alignment scores in patients with mixed dentition. Quality of life measures for the aligners previously were assessed by Nedwed et al27 in an adult population with findings that showed: 44% of patients experienced no speech i mpairment ; 34 % had no pa in ; 54% experienced mild pain while wearing aligners ; and 44% of the patients reported difficulty in chewing. These numbers are slightly higher than reported in this study, which perhaps implies a greater adaptability of the mixed dentition patient to tre atment. In contrast, Miller et al12 showed that the patients treated with Invisalign had quality of life values that returned to near baseline levels by day 7 He also showed that subjects in the fixed appliance group took more pain medications than those in the Invisalign group at days 2 and 3.12 In his survey of 357 adolescents, Bernabe et al28 found 38.7% of respondents reported quality of life to be severely affected with fixed appliances, versus only 20% who had exclusively used removable appliances. T hese values are in general agreement with our findings.

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23 As with other removable appliances, compliance was an issue in this study. Both Boyd29 and Phan30 noted that adult patients who fail to wear the aligners at least 22 hours per day are unlikely to achieve desired results. Lindaurer et al31 found that one in six patients lost their prescribed essix retainers, with the majority of those losses being ascr ibed to the clear and removable nature of the essix retainer --properties that are similar to Invisalign aligners. Petren23 found one third of the patients who utilized a removable plate for posterior crossbite correction to be non -complaint. Compliance lik ely played a role in the large standard deviations in this study. Future studies are needed in this area, possibly utilizing nonpatient reported compliance measures, such as compliance indicators on Invisalign Teen.

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24 CHAPTER 5 CONCLUSIONS Invisa lign treatment in mixed dentition yielded varied treatmen t results. The following conclusions can be made: 1 Gingival and tooth health showed no change form baseline to week 24 indi cating that Invisalign offers a hygienic modality of treatment for patients in the mixed dentition. 2 Littles Index scores were reduced in the majority of subjects. 3 Correction of anterior and posterior crossbite was effective in approximately 50% of the cases through 24 weeks. 4 Deep bite correction is difficult movement using aligners in mixed dentition. 5 Quality of life was not impacted for the majority of the mixed dentition patients who were treated with the Invisalign system.

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25 REFERENCES 1. Kuo E Miller R J. Automated custom -manufacturing technology in orthodontics Am J Orthod Dentofacial Orthop, 2003. 123(5):57881. 2. Align Technology website: www.invisalign.com/Whatis/pages/FaQ.aspx Accessed Mar. 16, 2009 3. Food and Drug Administration. News Release. Available at: http://www.fda.gov/cdrh/pdf8/k081960.pdf ". Accessed Mar. 21, 2009 4. Littlewood, SJ, Tait, AG, Mandall, NA, Lewis, DH. The role of removable appliances in contemporary orthodont ics Br Dent J 2001. 191(6):304 6, 30910. 5. Kuncio D, Manganzini A, Shelton C, Freeman K. Invisalign and traditional orthodontic treatment postretention outcomes compared using the American Board of Orthodontics objective grading system Angle Orthod, 20 07. 77(5):8649. 6. Lagravere MO Flores -Mi r C. The treatment effects of Invisalign orthodontic aligners: a systematic review J Am Dent Assoc 2005. 136(12):17249. 7. Kravitz ND, Kusnoto B, BeGole E, Obrez A, Agran B. How well does Invisalign work? A pr ospective clinical study evaluating the efficacy of tooth movement with Invisalign. Am J Orthod Dentofacial Orthop, 2009. 135 (1):27 35. 8. Joffe L. Invisalign: early experiences J Orthod 2003. 30(4):348 52. 9. Boyd RL. Complex orthodontic treatment using a new protocol for the Invisalign appliance J Clin Orthod 2007. 41(9):525 47; quiz 523. 10. Zhang M, McGrath C, Hagg U. Changes in oral health related quality of life during fixed orthodontic appliance therapy Am J Orthod Dentofacial Orthop, 2008. 133(1):259. 11. Sergl HG, Klages U, Zentner A. Pain and discomfort during orthodontic treatment: causative factors and effects on compliance Am J Orthod Dentofacial Orthop, 1998. 114(6):684 91. 12. Miller KB, M cGorray SP, Womack R, Quintero, JC, Dolan, TA, Wheeler TT A comparison of treatment impacts between Invisalign aligner and fixed appliance therapy during the first week of treatment. Am J Orthod Dentofacial Orthop, 2007. 131(3):302 e1 9. 13. Turesky S, Gilmore ND, Glickman I. Reduced plaque for mation by the chloromethyl analogue of victamin C J Periodontol, 1970. 41(1):41 3. 14. Loesche WJ Clinical and microbiological aspects of chemotherapeutic agents used according to the specific plaque hypothesis. J Dent Res 1979. 58(12):240412.

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26 15. Gor elick L, Geiger, AM, Gwinnett AJ. Incidence of white spot formation after bonding and banding. Am J Orthod 1982. 81(2):93 8. 16. Berchier CE, Slot DE Haps S, Van der Weijden, GA. The efficacy of dental floss in addition to a toothbrush on plaque and parameters of gingival inflammation: a systematic review Int J Dent Hyg 2008. 6 (4):26579. 17. Naranjo AA, Trivino ML, Jaramillo A, Betancourth M. Changes in the subgingival microbiota and periodontal parameters before and 3 months after bracket placemen t. Am J Orthod Dentofacial Orthop, 2006. 130(3):275 e1722. 18. Lee SM, Yoo SY Kim HS, Kim KW, Kook JK. Prevalence of putative periodontopathogens in subgingival dental plaques from gingivitis lesions in Korean orthodontic patients J Microbiol 2005. 43(3):2605. 19. Miethke, RR Brauner, K. A Comparison of the periodontal health of patients during treatment with the Invisalign system and with fixed lingual appliances J Orofac Orthop, 2007. 68(3):22331. 20. Harrison, JE Ashby, D. Orthodontic treatmen t for posterior crossbites Cochrane Database Syst Rev, 2001(1): p. CD000979. 21. McNally MR, Spary DJ, Rock WP. A randomized controlled trial comparing the quadhelix and the expansion arch for the correction of crossbite. J. Orthod ., 2005. 32(1):29 35. 2 2. Kurol J Berglund L. Longitudinal study and cost benefit analysis of the effect of early treatment of posterior cross bites in the primary dentition. Eur J Orthod 1992. 14(3):173 9. 23. Petren S Bondemark L. Correction of unilateral posterior crossbite in the mixed dentition: a randomized controlled trial Am J Orthod Dentofacial Orthop, 2008. 133(6): 790 e713. 24. Kennedy DB Osepchook M. Unilateral posterior crossbite with mandibular shift: a review J Can Dent Assoc 2005. 71(8):56973. 25. Petren S Bondemark SL, Soderfeldt B. A systematic review concerning early orthodontic treatment of unilateral posterior crossbite Angle Orthod, 2003. 73(5):588 96. 26. Millett DT, Cunningham SJ OBrien KD, Benson P, Williams A. de Oliveira, CM. Orthod ontic treatment for deep bite and retroclined upper front teeth in children. Cochrane Database Syst Rev, 2006(4): p. CD005972. 27. Nedwed V Miethke RR. Motivation, acceptance and problems of invisalign patients. J Orofac Orthop, 2005. 66(2):162 73.

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27 28. Bernabe E, Sheiham A de Oliveira CM. Impacts on daily performances related to wearing orthodontic appliances Angle Orthod, 2008. 78(3):4826. 29. Boyd RL. Esthetic orthodontic treatment using the invisalign appliance for moderate to complex malocclusio ns J Dent Educ 2008. 72(8):94867. 30. Phan X Ling PH. Clinical limitations of Invisalign J Can Dent Assoc, 2007 ; 73(3):2636. 31. Lindauer SJ Shoff RC. Comparison of Essix and Hawley retainers J Clin Orthod, 1998. 32(2):957.

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28 BIOGRAPHICAL SKETCH Brion Long graduated magna cum laude from the University of Oregon with a Bachelor of Science in General Science. He then went on to obtain his Doctor of Dental Medicine from Oregon Health Sciences Universi ty, graduating with honors. He received hi s M.S from the University of Florida in the summer of 2009.