- Email: [email protected]
Effect of lip bumpers on mandibular arch dimensions
REVIEW ARTICLE
Effect of lip bumpers on mandibular arch dimensions Dena Ibrahim Hashisha and Yehya Ahmed Mostafab Cairo, Egypt Introduction: The aim of this systematic review was to examine the effects of lip bumper therapy on mandibular arch dimensions. Methods: A literature survey of PubMed, EMBASE, Cochrane Central, and Cochrane Database of Systematic Reviews (www.cochrane.org) was conducted from December 1968 to January 2007. Human studies, randomized clinical trials, prospective and retrospective studies, and studies discussing the effect of lip bumpers on the arch and teeth were included. Two reviewers independently selected and extracted the data. Results: Of the 52 studies found in the search, only 1 met the inclusion criteria. Conclusions: The results showed increases in arch dimensions that included an increase in arch length. This was attributed to incisor proclination, distalization, and distal tipping of the molars. There was also an increase in the arch width seen in the intercanine and deciduous intermolar and premolar distances. The long-term stability of the effects of the lip bumper need to be elucidated. (Am J Orthod Dentofacial Orthop 2009;135:106-9)
I
n the extraction vs nonextraction debate, there has been growing interest in nonextraction modalities of treatment. The lip bumper (LB) can be used in nonextraction patients. The primary purposes of an LB have been to reduce mandibular anterior crowding,1-6 and to increase arch width and length.1,2,4,7-12 It has also been claimed that an LB maintains the position of the first molar and leeway space through molar anchorage.1,3,5,6,9-11,13 Several studies have discussed the effects of the LB.1-18 Systematic reviews, the backbone of evidencebased dentistry, are designed not only to identify all relevant information in the literature, but also to evaluate the quality of the information and then, if possible, to summarize the results from the strongest (or least biased) studies.19 Therefore, it seemed important to conduct a systematic review to interpret the results of LB studies. In this study, many sources were systematically searched, assessed, and evaluated to answer the following question: what are the effects of the LB on mandibular arch dimensions (length, width, and perimeter) in adolescents compared with untreated patients? From the Department of Orthodontics and Dentofacial Orthopedics, Faculty of Dentistry, Cairo University, Cairo, Egypt. a Resident. b Professor and chairperson. Reprint requests to: Yehya A. Mostafa, Department of Orthodontics and Dentofacial Orthopedics, Cairo University, Faculty of Dentistry, P.O. Box 60, Mina Garden Post Office, October City, Cairo 12582, Egypt; e-mail, [email protected]. Submitted, June 2007; revised and accepted, October 2007. 0889-5406/$36.00 Copyright © 2009 by the American Association of Orthodontists. doi:10.1016/j.ajodo.2007.10.038
106
MATERIAL AND METHODS
To identify all studies about the effect of LBs, a computer search was conducted of PubMed (http:// www.ncbi.nlm.nih.gov/sites/entrez), EMBASE, Cochrane Central, and Cochrane Database of Systematic Reviews from December 1968 to January 2007. The terms used in literature search were “lip bumper, arch length, arch width, arch dimension, arch circumference, arch depth, incisor proclination, lip sucking, lip habits, and orthodontics.” The following journals was searched separately to locate any missing articles from the PubMed search: Angle Orthodontist, American Journal of Orthodontics and Dentofacial Orthopedics, Journal of Orthodontics, and European Journal of Orthodontics. RESULTS
Our first step was to identify eligible studies based on their titles and abstracts; we found 52 abstracts. When we compared the separate searches of the previously mentioned journals with the PubMed search, we found no missing articles. The 52 studies were included. The second step was to apply our inclusion and exclusion criteria to each study. Human studies, randomized clinical trials, prospective and retrospective studies, studies discussing the effect of lip bumpers on the arch and teeth, and those in English were included. Excluded articles were mainly animal studies, case reports, case series, review articles, abstracts, in-vitro studies, discussions and interviews, articles in a language other than English, and those that did not follow the objective of this review. The selection was made by 2 researchers separately (made by the
Hashish and Mostafa 107
American Journal of Orthodontics and Dentofacial Orthopedics Volume 135, Number 1
2 authors). Their results were compared to identify discrepancies and reach mutual agreement. Sixteen studies seemed to meet the inclusion criteria. Their reference lists were searched for any missing articles from the database search. Information was extracted in a standardized manner from every retrieved article. Each study had to have a suitable sample size and a control group, mention the sexes and ages of the subjects, use study casts and lateral cephalometrics, and confirm reliability through error measurement. Fifteen studies were rejected because of methodological errors (Fig and Table). If 2 or more articles had evaluated the same technique, a meta-analysis was planned. The article by Davidovitch et al1 was the only 1 finally selected. This article discussed a prospective clinical trial to study the effect of LB therapy on patients in the mixed dentition with mild to moderate mandibular arch deficiency. Thirty-four patients, ages 7.9 to 13.1 years with 3 to 8 mm of mandibular crowding, were divided into 2 groups: control (n ⫽ 18) and experimental (n ⫽ 16). The experimental group underwent continuous LB therapy, whereas the control group was monitored without active treatment. The patients were recalled every 4 to 6 weeks for appliance adjustment and monitoring, with a total treatment period of 6 months. Arch-dimension changes were assessed with study casts. Alterations of mandibular incisor position were measured from the lateral cephalometric radiographs. Mandibular left first permanent molar position changes were determined from both the lateral cephalometric and tomographic radiographs. Measurements of molar movement were also compared. According to the authors, arch perimeter was the distance from the mesial contact point of the first permanent molar on 1 side of the mandibular arch to the same point on the contralateral molar. Arch length was measured as the perpendicular length of a line between the central pits of the first permanent molars through the contacts of the central incisors. Arch-width changes were measured on the dental casts between the deciduous molars (central fossa to central fossa) and the canines (cusp to cusp). The incisor proclination was measured as the angle formed by the long axis of the mandibular central incisor to the mandibular plane.1 DISCUSSION
Because of the increased interest in LB as an alternative method to extraction, many studies were conducted to determine its effects on arch width and length. The therapeutic effects have not always been elucidated.
Fig. QUOROM flow diagram (RCT, randomized clinical trial). Table.
Studies that fulfilled the selection criteria but were later rejected
Author
Year
Missing criteria
Moin and Bishara7 Solomon et al14 Waring et al15 Ferris et al2 Ferro et al16 Vanarsdall et al17 Murphy et al8 Sankey et al18 Hasler and Ingervall9 O’Donnell et al3 Grossen and Ingervall10 Werner et al11 Nevant et al4 Osborn et al5 Bergersen6
2007 2006 2005 2005 2004 2004 2003 2000 2000 1998 1995 1994 1991 1991 1972
1, 3, 5 1, 2 1, 2, 5 1, 4 1, 2, 3, 5 5 1 1 1 1 1, 2, 5 1, 2 1, 2, 4 1 1, 2, 5
Criteria: 1, control group; 2, sex; 3, age; 4, study casts and cephalometric analysis; 5, measurement error.
In our systematic review, we tried to collect and analyze all data from previous articles related to our key question: what are the effects of the LB on mandibular arch dimensions in adolescents compared with untreated patients? Many studies were excluded by our exclusion criteria (Table). One study1 quantified
108 Hashish and Mostafa
the effects correctly, making it clear that the LB can increase arch dimensions and contribute to crowding relief in mixed dentition. In this prospective study, to separate any influence of other simultaneous treatment, the LB was the only therapy used to affect the mandibular arch directly. The tools used to measure specific tooth movement were also evaluated. All data were analyzed independently by 2 observers to compare interobserver reliability and the efficacy of the radiographic imaging techniques used. To elucidate the true effects of LB for increasing the arch dimensions, the following discussion is divided into 3 subheads to determine the contributing factors for increasing arch length. Molar distalization
Davidovitch et al1 reported that quantification of molar movement is related to the imaging technique used. Although cephalometric data showed no statistical differences in molar position between the experimental and control subjects, significant treatment effects were deterined by tomographic measurements. All treated subjects had distal (negative) molar tipping, regardless of the radiographic technique used for data gathering. However, quantitative differences in this movement were noted between the radiographic imaging techniques. Tomographic data (⫺6.31° ⫾ 1.28°) showed approximately twice the angulation changes as measured from lateral cephalometric radiographs (⫺3.38° ⫾ 3.67°). Anteroposterior changes in molar position were statistically different for treated vs untreated subjects when compared tomographically (⫺1.66 ⫾ 0.53 mm and ⫹0.65 ⫾ 0.59 mm, respectively), with a negative sign indicating distal movement. No significant difference was found in comparisons with the cephalometric data. Bergersen6 reported that 95% of the patients showed distalization that depended on the number of days that the LB was used and number of times that it was linearly advanced from the molars from both sides. The patients who had 50 days of LB treatment showed 0.853 mm of distalization, and those who had more than 50 days of LB treatment showed 1.00 mm of distalization. In patients without LB advancement, the molars moved 0.78 mm distally. Patients had a mean of 1.49 mm of lip bumper advancement, and the molars moved 1.00 mm distally. Subtelny and Sakuda13 showed 88% distalization. Osborn et al5 and Grossen and Ingervall10 found minimal posterior movement of the molars, whereas O’Donnell et al3 found 0.95 mm of distal movement of the first molars.
American Journal of Orthodontics and Dentofacial Orthopedics January 2009
Arch width
Davidovitch et al1 found that untreated subjects had reductions in transverse dimensions between the deciduous second molars (⫺0.33 ⫾ 0.67 mm) and the permanent canines (⫺0.25 ⫾ 0.92 mm). Those treated for 6 months with an LB showed an increase in arch width between the second deciduous molars (⫹1.83 ⫾ 1.32 mm) and the permanent canines (⫹1.80 ⫾ 0.41 mm). Osborn et al5 found average increases in intermolar width and widths at the first and second premolars of 1.92, 2.5, and 2.43 mm, respectively. There was no correlation between the mean changes in arch length and length of treatment. Cetlin and Ten Hoeve12 indicated that the increase in arch width was the primary cause of increased arch circumference. The increases in arch width at the molars and first premolars were 5.5 and 4 mm, respectively. Nevant et al4 reported the expansion to be 2.09 mm at the first premolars, whereas Grossen and Ingervall10 measured the expansion at 2.1 and 2.2 mm at the first and second premolars, respectively. Werner et al11 showed significant increases throughout the arch but most notably at the second premolars (average, 4.1 mm). Hasler and Ingervall9 found the main effect of the maxillary LB to be widening of the arch at the interpremolar area, and the intermolar and intercanine changes were negligible. Murphy et al8 found that 50% of the total expansion occurred within about the first 100 days, and 90% of the total expansion was achieved during the first 300 days, making it unnecessary to leave the appliance in place for longer than 300 days. However, the authors did not determine whether this increase was due to growth or LB therapy. Ferris et al2 reported that intercanine width increased the least (1.37 ⫾ 1.7 mm) and inter-first premolar width increased the most (4.7 ⫾ 2.6 mm). Moin and Bishara7 found the greatest mean expansions at the first (5.0 ⫾ 2.2 mm) and second (3.4 ⫾ 2.2 mm) premolar widths. From this, it is evident that an important contributing factor to arch length increase by the LB is the increase in arch width in the buccal segment. There is a need to quantify the amount of width increase in relation to the total increase in arch length. Incisor proclination
Davidovitch et al1 repoted that treated subjects had an angular change in incisor inclination nearly 6 times greater (3.19° ⫾ 2.40°) than did the untreated subjects (0.5° ⫾ 1.7°). Anteroposterior changes in incisor posi-
American Journal of Orthodontics and Dentofacial Orthopedics Volume 135, Number 1
tion measured as movement of the apex did not differ significantly between the 2 groups. Bergersen6 reported forward migration of the mandibular incisors in 95% of the subjects. There was no significant correlation between the time that the LB was placed or the linear advancement and the forward movement. In 78 days, the average movement was 1.45 mm. Osborn et al5 reported that the mean increase in arch length of 1.2 mm was largely attributed to anterior tipping of the mandibular incisors in 78% of the subjects. These results were similar to those of Nevant et al,4 Grossen and Ingervall,10 and O’Donnell et al.3 Hasler and Ingervall9 found that incisor proclination was not significant (1.4°). With the limitations of available studies and total samples for this systematic review, we can state that the LB is an effective appliance for increasing arch dimensions in the mixed dentition. All studies agreed that it has a positive effect on the arch. According to Davidovitch et al,1 the perimeter increase was caused by angular and linear changes of molar position, passive increases in mandibular arch transverse dimensions, and incisor proclination. Molar movement and transverse increases were found to contribute as much, if not more, to increased arch perimeter as did incisor proclination. CONCLUSIONS
In this systematic review, we discussed the effects of LB treatment. The key question was “what are the effects of the LB on mandibular arch dimensions in adolescents compared with untreated patients?” Our results showed increases in arch dimensions that included an increase in arch length. This was attributed to incisor proclination, distalization, and distal tipping of the molars. There were also increases in arch width and intercanine and deciduous intermolar or premolar distances. The long-term stability of the effects of the LB need to be elucidated. REFERENCES 1. Davidovitch M, McInnis D, Lindauer SJ. The effect of lip bumper therapy in mixed dentition. Am J Orthod Dentofacial Orthop 1997;111:52-8.
Hashish and Mostafa 109
2. Ferris T, Alexander RG, Boley J, Buschang PH. Long-term stability of combined rapid palatal expansion-lip bumper therapy followed by full fixed appliances. Am J Orthod Dentofacial Orthop 2005;128:310-25. 3. O’Donnell S, Nanda RS, Ghosh J. Perioral forces and dental changes resulting from mandibular lip bumper treatment. Am J Orthod Dentofacial Orthop 1998;113:247-55. 4. Nevant CT, Buschang PH, Alexander RG, Steffen JM. Lip bumper therapy for gaining arch length. Am J Orthod Dentofacial Orthop 1991;100:330-6. 5. Osborn WS, Nanda RS, Currier GF. Mandibular arch perimeter changes with lip bumper treatment. Am J Orthod Dentofacial Orthop 1991;99:527-32. 6. Bergersen EO. A cephalometric study of the clinical use of the mandibular labial bumper. Am J Orthod 1972;61:578-602. 7. Moin K, Bishara SE. An evaluation of buccal shield treatment: a clinical and cephalometric study. Angle Orthod 2007;77: 57-63. 8. Murphy CC, Magness, English JD, Frazier-Bowers SA, Salas AM. A longitudinal study of incremental expansion using a mandibular lip bumper. Angle Orthod 2003;73:396-400. 9. Hasler R, Ingervall B. The effect of a maxillary lip bumper on tooth position. Eur J Orthod 2000;22:25-32. 10. Grossen J, Ingervall B. The effect of a lip bumper on lower dental arch dimensions and tooth position. Eur J Orthod 1995; 17:129-34. 11. Werner SP, Shivapuja PK, Harris EF. Skeletodental changes in the adolescent accruing from use of the lip bumper. Angle Orthod 1994;64:13-22. 12. Cetlin NM, Ten Hoeve A. Nonextraction treatment. J Clin Orthod 1983;17:396-413. 13. Subtelny JD, Sakuda M. Muscle function, oral malformation and growth changes. Am J Orthod 1966;52:495-517. 14. Solomon MJ, English JD, Magness WB, Mckee CJ. Long term stability of lip bumper therapy followed by fixed appliances. Angle Orthod 2006;76:36-42. 15. Waring DT, Pender N, Counihan D. Mandibular arch changes following non extraction treatment. Aust Orthod J 2005;21: 111-6. 16. Ferro F, Perillo L, Ferro A. Non extraction short-term arch changes. Prog Orthod 2004;5:18-43. 17. Vanarsdall RL, Secchi AG, Chung CH, Katz SH. Mandibular basal structure response to lip bumper treatment in the transverse dimension. Angle Orthod 2004;74:473-9. 18. Sankey WL, Buschang PH, English J, Owen AH. Early treatment of vertical skeletal dysplasia: the hyperdivergent phenotype. Am J Orthod Dentofacial Orthop 2000;118:317-27. 19. Bader J, Ismail A. Survey of systematic reviews in dentistry. Am J Dent Assoc 2004;135:464-73.
Effect of lip bumpers on mandibular arch dimensions Dena Ibrahim Hashisha and Yehya Ahmed Mostafab Cairo, Egypt Introduction: The aim of this systematic review was to examine the effects of lip bumper therapy on mandibular arch dimensions. Methods: A literature survey of PubMed, EMBASE, Cochrane Central, and Cochrane Database of Systematic Reviews (www.cochrane.org) was conducted from December 1968 to January 2007. Human studies, randomized clinical trials, prospective and retrospective studies, and studies discussing the effect of lip bumpers on the arch and teeth were included. Two reviewers independently selected and extracted the data. Results: Of the 52 studies found in the search, only 1 met the inclusion criteria. Conclusions: The results showed increases in arch dimensions that included an increase in arch length. This was attributed to incisor proclination, distalization, and distal tipping of the molars. There was also an increase in the arch width seen in the intercanine and deciduous intermolar and premolar distances. The long-term stability of the effects of the lip bumper need to be elucidated. (Am J Orthod Dentofacial Orthop 2009;135:106-9)
I
n the extraction vs nonextraction debate, there has been growing interest in nonextraction modalities of treatment. The lip bumper (LB) can be used in nonextraction patients. The primary purposes of an LB have been to reduce mandibular anterior crowding,1-6 and to increase arch width and length.1,2,4,7-12 It has also been claimed that an LB maintains the position of the first molar and leeway space through molar anchorage.1,3,5,6,9-11,13 Several studies have discussed the effects of the LB.1-18 Systematic reviews, the backbone of evidencebased dentistry, are designed not only to identify all relevant information in the literature, but also to evaluate the quality of the information and then, if possible, to summarize the results from the strongest (or least biased) studies.19 Therefore, it seemed important to conduct a systematic review to interpret the results of LB studies. In this study, many sources were systematically searched, assessed, and evaluated to answer the following question: what are the effects of the LB on mandibular arch dimensions (length, width, and perimeter) in adolescents compared with untreated patients? From the Department of Orthodontics and Dentofacial Orthopedics, Faculty of Dentistry, Cairo University, Cairo, Egypt. a Resident. b Professor and chairperson. Reprint requests to: Yehya A. Mostafa, Department of Orthodontics and Dentofacial Orthopedics, Cairo University, Faculty of Dentistry, P.O. Box 60, Mina Garden Post Office, October City, Cairo 12582, Egypt; e-mail, [email protected]. Submitted, June 2007; revised and accepted, October 2007. 0889-5406/$36.00 Copyright © 2009 by the American Association of Orthodontists. doi:10.1016/j.ajodo.2007.10.038
106
MATERIAL AND METHODS
To identify all studies about the effect of LBs, a computer search was conducted of PubMed (http:// www.ncbi.nlm.nih.gov/sites/entrez), EMBASE, Cochrane Central, and Cochrane Database of Systematic Reviews from December 1968 to January 2007. The terms used in literature search were “lip bumper, arch length, arch width, arch dimension, arch circumference, arch depth, incisor proclination, lip sucking, lip habits, and orthodontics.” The following journals was searched separately to locate any missing articles from the PubMed search: Angle Orthodontist, American Journal of Orthodontics and Dentofacial Orthopedics, Journal of Orthodontics, and European Journal of Orthodontics. RESULTS
Our first step was to identify eligible studies based on their titles and abstracts; we found 52 abstracts. When we compared the separate searches of the previously mentioned journals with the PubMed search, we found no missing articles. The 52 studies were included. The second step was to apply our inclusion and exclusion criteria to each study. Human studies, randomized clinical trials, prospective and retrospective studies, studies discussing the effect of lip bumpers on the arch and teeth, and those in English were included. Excluded articles were mainly animal studies, case reports, case series, review articles, abstracts, in-vitro studies, discussions and interviews, articles in a language other than English, and those that did not follow the objective of this review. The selection was made by 2 researchers separately (made by the
Hashish and Mostafa 107
American Journal of Orthodontics and Dentofacial Orthopedics Volume 135, Number 1
2 authors). Their results were compared to identify discrepancies and reach mutual agreement. Sixteen studies seemed to meet the inclusion criteria. Their reference lists were searched for any missing articles from the database search. Information was extracted in a standardized manner from every retrieved article. Each study had to have a suitable sample size and a control group, mention the sexes and ages of the subjects, use study casts and lateral cephalometrics, and confirm reliability through error measurement. Fifteen studies were rejected because of methodological errors (Fig and Table). If 2 or more articles had evaluated the same technique, a meta-analysis was planned. The article by Davidovitch et al1 was the only 1 finally selected. This article discussed a prospective clinical trial to study the effect of LB therapy on patients in the mixed dentition with mild to moderate mandibular arch deficiency. Thirty-four patients, ages 7.9 to 13.1 years with 3 to 8 mm of mandibular crowding, were divided into 2 groups: control (n ⫽ 18) and experimental (n ⫽ 16). The experimental group underwent continuous LB therapy, whereas the control group was monitored without active treatment. The patients were recalled every 4 to 6 weeks for appliance adjustment and monitoring, with a total treatment period of 6 months. Arch-dimension changes were assessed with study casts. Alterations of mandibular incisor position were measured from the lateral cephalometric radiographs. Mandibular left first permanent molar position changes were determined from both the lateral cephalometric and tomographic radiographs. Measurements of molar movement were also compared. According to the authors, arch perimeter was the distance from the mesial contact point of the first permanent molar on 1 side of the mandibular arch to the same point on the contralateral molar. Arch length was measured as the perpendicular length of a line between the central pits of the first permanent molars through the contacts of the central incisors. Arch-width changes were measured on the dental casts between the deciduous molars (central fossa to central fossa) and the canines (cusp to cusp). The incisor proclination was measured as the angle formed by the long axis of the mandibular central incisor to the mandibular plane.1 DISCUSSION
Because of the increased interest in LB as an alternative method to extraction, many studies were conducted to determine its effects on arch width and length. The therapeutic effects have not always been elucidated.
Fig. QUOROM flow diagram (RCT, randomized clinical trial). Table.
Studies that fulfilled the selection criteria but were later rejected
Author
Year
Missing criteria
Moin and Bishara7 Solomon et al14 Waring et al15 Ferris et al2 Ferro et al16 Vanarsdall et al17 Murphy et al8 Sankey et al18 Hasler and Ingervall9 O’Donnell et al3 Grossen and Ingervall10 Werner et al11 Nevant et al4 Osborn et al5 Bergersen6
2007 2006 2005 2005 2004 2004 2003 2000 2000 1998 1995 1994 1991 1991 1972
1, 3, 5 1, 2 1, 2, 5 1, 4 1, 2, 3, 5 5 1 1 1 1 1, 2, 5 1, 2 1, 2, 4 1 1, 2, 5
Criteria: 1, control group; 2, sex; 3, age; 4, study casts and cephalometric analysis; 5, measurement error.
In our systematic review, we tried to collect and analyze all data from previous articles related to our key question: what are the effects of the LB on mandibular arch dimensions in adolescents compared with untreated patients? Many studies were excluded by our exclusion criteria (Table). One study1 quantified
108 Hashish and Mostafa
the effects correctly, making it clear that the LB can increase arch dimensions and contribute to crowding relief in mixed dentition. In this prospective study, to separate any influence of other simultaneous treatment, the LB was the only therapy used to affect the mandibular arch directly. The tools used to measure specific tooth movement were also evaluated. All data were analyzed independently by 2 observers to compare interobserver reliability and the efficacy of the radiographic imaging techniques used. To elucidate the true effects of LB for increasing the arch dimensions, the following discussion is divided into 3 subheads to determine the contributing factors for increasing arch length. Molar distalization
Davidovitch et al1 reported that quantification of molar movement is related to the imaging technique used. Although cephalometric data showed no statistical differences in molar position between the experimental and control subjects, significant treatment effects were deterined by tomographic measurements. All treated subjects had distal (negative) molar tipping, regardless of the radiographic technique used for data gathering. However, quantitative differences in this movement were noted between the radiographic imaging techniques. Tomographic data (⫺6.31° ⫾ 1.28°) showed approximately twice the angulation changes as measured from lateral cephalometric radiographs (⫺3.38° ⫾ 3.67°). Anteroposterior changes in molar position were statistically different for treated vs untreated subjects when compared tomographically (⫺1.66 ⫾ 0.53 mm and ⫹0.65 ⫾ 0.59 mm, respectively), with a negative sign indicating distal movement. No significant difference was found in comparisons with the cephalometric data. Bergersen6 reported that 95% of the patients showed distalization that depended on the number of days that the LB was used and number of times that it was linearly advanced from the molars from both sides. The patients who had 50 days of LB treatment showed 0.853 mm of distalization, and those who had more than 50 days of LB treatment showed 1.00 mm of distalization. In patients without LB advancement, the molars moved 0.78 mm distally. Patients had a mean of 1.49 mm of lip bumper advancement, and the molars moved 1.00 mm distally. Subtelny and Sakuda13 showed 88% distalization. Osborn et al5 and Grossen and Ingervall10 found minimal posterior movement of the molars, whereas O’Donnell et al3 found 0.95 mm of distal movement of the first molars.
American Journal of Orthodontics and Dentofacial Orthopedics January 2009
Arch width
Davidovitch et al1 found that untreated subjects had reductions in transverse dimensions between the deciduous second molars (⫺0.33 ⫾ 0.67 mm) and the permanent canines (⫺0.25 ⫾ 0.92 mm). Those treated for 6 months with an LB showed an increase in arch width between the second deciduous molars (⫹1.83 ⫾ 1.32 mm) and the permanent canines (⫹1.80 ⫾ 0.41 mm). Osborn et al5 found average increases in intermolar width and widths at the first and second premolars of 1.92, 2.5, and 2.43 mm, respectively. There was no correlation between the mean changes in arch length and length of treatment. Cetlin and Ten Hoeve12 indicated that the increase in arch width was the primary cause of increased arch circumference. The increases in arch width at the molars and first premolars were 5.5 and 4 mm, respectively. Nevant et al4 reported the expansion to be 2.09 mm at the first premolars, whereas Grossen and Ingervall10 measured the expansion at 2.1 and 2.2 mm at the first and second premolars, respectively. Werner et al11 showed significant increases throughout the arch but most notably at the second premolars (average, 4.1 mm). Hasler and Ingervall9 found the main effect of the maxillary LB to be widening of the arch at the interpremolar area, and the intermolar and intercanine changes were negligible. Murphy et al8 found that 50% of the total expansion occurred within about the first 100 days, and 90% of the total expansion was achieved during the first 300 days, making it unnecessary to leave the appliance in place for longer than 300 days. However, the authors did not determine whether this increase was due to growth or LB therapy. Ferris et al2 reported that intercanine width increased the least (1.37 ⫾ 1.7 mm) and inter-first premolar width increased the most (4.7 ⫾ 2.6 mm). Moin and Bishara7 found the greatest mean expansions at the first (5.0 ⫾ 2.2 mm) and second (3.4 ⫾ 2.2 mm) premolar widths. From this, it is evident that an important contributing factor to arch length increase by the LB is the increase in arch width in the buccal segment. There is a need to quantify the amount of width increase in relation to the total increase in arch length. Incisor proclination
Davidovitch et al1 repoted that treated subjects had an angular change in incisor inclination nearly 6 times greater (3.19° ⫾ 2.40°) than did the untreated subjects (0.5° ⫾ 1.7°). Anteroposterior changes in incisor posi-
American Journal of Orthodontics and Dentofacial Orthopedics Volume 135, Number 1
tion measured as movement of the apex did not differ significantly between the 2 groups. Bergersen6 reported forward migration of the mandibular incisors in 95% of the subjects. There was no significant correlation between the time that the LB was placed or the linear advancement and the forward movement. In 78 days, the average movement was 1.45 mm. Osborn et al5 reported that the mean increase in arch length of 1.2 mm was largely attributed to anterior tipping of the mandibular incisors in 78% of the subjects. These results were similar to those of Nevant et al,4 Grossen and Ingervall,10 and O’Donnell et al.3 Hasler and Ingervall9 found that incisor proclination was not significant (1.4°). With the limitations of available studies and total samples for this systematic review, we can state that the LB is an effective appliance for increasing arch dimensions in the mixed dentition. All studies agreed that it has a positive effect on the arch. According to Davidovitch et al,1 the perimeter increase was caused by angular and linear changes of molar position, passive increases in mandibular arch transverse dimensions, and incisor proclination. Molar movement and transverse increases were found to contribute as much, if not more, to increased arch perimeter as did incisor proclination. CONCLUSIONS
In this systematic review, we discussed the effects of LB treatment. The key question was “what are the effects of the LB on mandibular arch dimensions in adolescents compared with untreated patients?” Our results showed increases in arch dimensions that included an increase in arch length. This was attributed to incisor proclination, distalization, and distal tipping of the molars. There were also increases in arch width and intercanine and deciduous intermolar or premolar distances. The long-term stability of the effects of the LB need to be elucidated. REFERENCES 1. Davidovitch M, McInnis D, Lindauer SJ. The effect of lip bumper therapy in mixed dentition. Am J Orthod Dentofacial Orthop 1997;111:52-8.
Hashish and Mostafa 109
2. Ferris T, Alexander RG, Boley J, Buschang PH. Long-term stability of combined rapid palatal expansion-lip bumper therapy followed by full fixed appliances. Am J Orthod Dentofacial Orthop 2005;128:310-25. 3. O’Donnell S, Nanda RS, Ghosh J. Perioral forces and dental changes resulting from mandibular lip bumper treatment. Am J Orthod Dentofacial Orthop 1998;113:247-55. 4. Nevant CT, Buschang PH, Alexander RG, Steffen JM. Lip bumper therapy for gaining arch length. Am J Orthod Dentofacial Orthop 1991;100:330-6. 5. Osborn WS, Nanda RS, Currier GF. Mandibular arch perimeter changes with lip bumper treatment. Am J Orthod Dentofacial Orthop 1991;99:527-32. 6. Bergersen EO. A cephalometric study of the clinical use of the mandibular labial bumper. Am J Orthod 1972;61:578-602. 7. Moin K, Bishara SE. An evaluation of buccal shield treatment: a clinical and cephalometric study. Angle Orthod 2007;77: 57-63. 8. Murphy CC, Magness, English JD, Frazier-Bowers SA, Salas AM. A longitudinal study of incremental expansion using a mandibular lip bumper. Angle Orthod 2003;73:396-400. 9. Hasler R, Ingervall B. The effect of a maxillary lip bumper on tooth position. Eur J Orthod 2000;22:25-32. 10. Grossen J, Ingervall B. The effect of a lip bumper on lower dental arch dimensions and tooth position. Eur J Orthod 1995; 17:129-34. 11. Werner SP, Shivapuja PK, Harris EF. Skeletodental changes in the adolescent accruing from use of the lip bumper. Angle Orthod 1994;64:13-22. 12. Cetlin NM, Ten Hoeve A. Nonextraction treatment. J Clin Orthod 1983;17:396-413. 13. Subtelny JD, Sakuda M. Muscle function, oral malformation and growth changes. Am J Orthod 1966;52:495-517. 14. Solomon MJ, English JD, Magness WB, Mckee CJ. Long term stability of lip bumper therapy followed by fixed appliances. Angle Orthod 2006;76:36-42. 15. Waring DT, Pender N, Counihan D. Mandibular arch changes following non extraction treatment. Aust Orthod J 2005;21: 111-6. 16. Ferro F, Perillo L, Ferro A. Non extraction short-term arch changes. Prog Orthod 2004;5:18-43. 17. Vanarsdall RL, Secchi AG, Chung CH, Katz SH. Mandibular basal structure response to lip bumper treatment in the transverse dimension. Angle Orthod 2004;74:473-9. 18. Sankey WL, Buschang PH, English J, Owen AH. Early treatment of vertical skeletal dysplasia: the hyperdivergent phenotype. Am J Orthod Dentofacial Orthop 2000;118:317-27. 19. Bader J, Ismail A. Survey of systematic reviews in dentistry. Am J Dent Assoc 2004;135:464-73.