A systematic review on nickel-titanium palatal expanders: Prospectives and pitfalls

Transcription

1 Research Article A systematic review on nickel-titanium palatal expanders: Prospectives and pitfalls Suvetha Siva*, Ravindra Kumar Jain ABSTRACT Background: Since nickel-titanium (NiTi) palatal expanders are routinely used in orthodontic practice, to get a more detailed insight about, a systematic review was planned. This review was mainly aimed to evaluate skeletal and dental changes following fixed NiTi palatal expander used in orthodontic patients with constricted maxillary arches. Materials and Methods: The studies that were included in this review are mainly clinical trials that assessed the skeletal and dental arch changes through measurements on dental casts or cephalometric radiographs. The studies that included the surgical or other simultaneous treatment interventions during the active expansion period were excluded from this review. Results: After a full search in the following electronic databases: PubMed and Google Scholar, five articles were selected based on the initial inclusion criteria. Changes in the intermolar and intercanine widths were recorded as the variables of interest. Conclusion: Since only low level of evidence was obtained, no strong conclusions on dental or skeletal changes that occurred after NiTi palatal expander treatment were made. Clinicians need to rely on their clinical experience, expert opinions, and the present evidence concerning slow maxillary expansion technique. KEY WORDS: Nickel-titanium palatal expanders, Slow maxillary expansion, Slow palatal expansion INTRODUCTION Constricted maxillary arch is one of the common problems encountered in orthodontics which may manifest mostly as posterior crossbite. Timely treatment of such transverse discrepancies by maxillary expansion is recommended to reestablish proper function. The primary aim of maxillary expansion is to expand the maxillary and mandibular arches and reduce their interarch discrepancies. Maxillary expansion has been carried out for more than a century to correct the maxillary transverse deficiency. Three different expansion treatment modalities are used today: Slow maxillary expansion (SME), rapid maxillary expansion (RME), and surgically assisted maxillary expansion. Since each treatment modality has its advantages, disadvantages and controversies regarding their use exist. Practitioners select the appliance based on their personal experiences and the patient s age and malocclusion. [1,2] Access this article online Website: jprsolutions.info ISSN: RME has been used widely [3,4] and its associated limitations also have been reported. The limitations of RME include bite opening; [5] relapse, microtrauma of the TMJ, and the midpalatal suture; [6-8] root resorption, tissue impingement, and pain; [7-9] and excessive tipping of anchor teeth. [9] SME produces less tissue resistance around the circummaxillary region. This improves the bone formation in the intermaxillary suture and also theoretically eliminates or reduces the limitations of RME. [2,10,11] For SME, only n [10,12] of force is applied to the maxillary region, depending on the age of the patient, compared to n for RME. [1,2,13] The most frequently used SME appliances are nickel-titanium (NiTi)-expanders [3,8,10,14] and quadhelix. [15-17] Although the objective of both the appliances is to achieve physiological intermaxillary sutural expansion, the design and activation are different for both the appliances. Clinicians should not think that the skeletal and dental effects of the two appliances are equal, and they should consider the two treatment modalities separately. Department of Orthodontics, Saveetha Dental College, Saveetha Institute of Medical and Technical Sciences, Saveetha University, Chennai, Tamil Nadu, India *Corresponding author: Suvetha Siva, Saveetha Dental College, Saveetha Institute of Medical and Technical Sciences, Saveetha University, Velappanchavadi, Chennai, Tamil Nadu, India. suvetha150992@gmail.com Received on: ; Revised on: ; Accepted on:

2 This review was conducted to evaluate the skeletal and dental changes after in patients with constricted arches, using all available published scientific literature. Aim The question that needs to be addressed in this study is as follows: Is NiTi palatal expander an effective appliance for SME? Structured Question Is there a difference in the amount of expansion between the and other expansion appliances? Pico Analysis Patients - Patients with posterior crossbites or constricted maxillary arches Intervention - NiTi palatal expander Comparison - To compare NiTi expander with the other reported expanders Outcome - To evaluate the amount of intermolar and intercanine width changes following slow expansion with NiTi expanders. MATERIALS AND METHODS The selected literature search terms are slow palatal expansion, SME, and. We conducted computerized searches using the following databases: PubMed, Google Scholar, Medline, Medline in process, Embase from 1966 to week 1 of October 2017, and other non-indexed citations until October 6, The following inclusion criteria were used to select the appropriate articles clinical trials where (1) SME done with NITI expanders, (2) measurements were made from dental casts or facial radiographs, and. (3) no surgical or other simultaneous treatment that could affect SME during the Evaluation period. The article abstracts were read thoroughly to determine the eligibility of articles. Two researchers independently completed the selection process. If a discrepancy arose, a third researcher helped in making the final decision. Articles for which the abstracts did not present enough relevant information to make a final decision regarding their inclusion were rejected. The reference lists of the selected articles were also searched for additional relevant publications that may have missed in the database searches. All of the articles from the selected abstracts were evaluated independently, and conclusion regarding which articles should be included in the review was drawn. For articles in which relevant data were not available, the authors were contacted to obtain the required extra information. RESULTS Google Scholar and PubMed had the greatest diversity of abstracts. All of the selected abstracts from PubMed were included in Google Scholar and vice versa. After completing the review of the selected abstracts, the reference lists of the selected articles were included and are displayed in Table 1. A summary of sample size, method, and the appliance used in the six studies is presented in Table 2. DISCUSSION The aim of any evidence-based practice is to provide the best possible treatment only based on a sound evidence. [23] The highest level is represented by randomized controlled trials (Level I), followed by non-randomized controlled trials or quasiexperimental studies (Level II). Both these levels have two subcategories each: systematic reviews (if possible, meta-analysis) (subgroup A) and analyses of individual studies (subgroup B). Non-experimental descriptive studies (observational, cohorts, and case reports) are Level III, and expert opinions are the lowest level (Level IV). Basic research (animal and human physiology) can lead to inaccurate assumptions and does not represent direct evidence for clinical practice. [24] If the higher level of evidence is absent, clinicians have to make decisions based on lower levels of evidence. As lower levels of evidence are more prone to confounding and selection bias, [25] clinicians Table 1: Sensitivity of electronic database selected Database Key words Number of results Number selected % of selected abstracts Google scholar SME or slow palatal expansion; PubMed, Medline, Medline SME or slow palatal expansion; in process, Embasse Other publications SME or slow palatal expansion; Reference lists NA NA NA 0 NA: Not applicable, SME: Slow maxillary expansion, NiTi: Nickel titanium 89

3 Table 2: Methodology of selected studies Authors Sample size Control group Marzban and Nanda [18] Ciambotti et al. [19] Case report of three patients (one female and two male) 25 patients were divided into two groups (13 using NiTi expander and 12 using RME) Evaluation Appliance Active expansion period No Model casts NiTi expander (bands) Yes Study models, occlusal radiographs Donohue 29 patients (19 female and 9 males) Yes Study models NiTi expander et al. [20] (bands) Q X Paul 10 subjects (5 female and 5 male with No Study models, frontal, NiTi et al. [21] mean age of 7 15 years) lateral cephalograms, expander (bands) Ferrario 4 primary (mean age 5.8 years) and 9 et al. [22] mixed dentition (mean age 8.7 years) children 7 control children Yes RME: Rapid maxillary expansion, Q X : Quad helix, NiTi: Nickel titanium and occlusal radiographs Geometric mathematical models 1 4 months NiTi expander 127 days 153 days (bands) and RME appliance 3 4 months NiTi expander 7 months 6 months should be careful in analyzing the study limitations. The selection of treatment can not be dictated by the scientific evidence alone. During the making of health-care decisions, clinicians should consider a combination of values from patients and from professionals (clinical, personal, and social) which will determine if the intervention benefits are worth the costs. [26] Therefore, the application of evidence into clinical practice has to be related both to the professional expertise and the needs of the patient. The NiTi palatal expander was introduced by Arndt. [27] It generates constant, optimal expansion forces. The central component is made of a thermally activated NiTi alloy and rest of the component is made of stainless steel. The expander may be used along with conventional fixed appliances, requiring only an addition of lingual sheath on the molar bands. [18] The action of the appliance is the consequence of NiTi s shape memory and transition temperature effects. [18] The NiTi component has a transition temperature of about 94 F. At room temperature, the expander is too stiff and is difficult to bend for insertion. Chilling the expander softens the central component which will allow easy manipulation. Once placed, it stiffens and begins to return to its original shape. An increment of 3 mm of expansion exerts 350 g of force, and as the expander is deactivated, the Nt alloy provides uniform force levels. The expander is available in different sizes ranging from 26 mm to 44 mm. The simple way to determine the appropriate size is measuring the intermolar width at the central fossae of the mandibular molars because the mesiolingual cusps of the maxillary molars occlude only with these fossae. If the mandibular molars are lingually tilted as in case of skeletal posterior crossbite compensation, which occurs most often, it is appropriate to add another 1 2 mm more to the expansion. In any case, 2 3 mm should be added for the overexpression of the expansion. If more than 8 mm of expansion is needed, two expanders should be used. In the study by Marzban and Nanda, [18] three cases were treated using NiTi palatal expander. They recorded a average of 3 mm expansion in the maxillary arch as measured on the model at the molar area. They concluded that orthodontic tooth movement and buccal tipping occur initially but are minimum. Third-order moments that are generated by the expander soon will upright the molars and provide stable, orthopedic maxillary expansion. The buccal segment of the mandibular arch will gradually upright itself, thus eliminating dental compensations which occurred from the pre-existing crossbite. Incorporation of this appliance into an existing fixed appliance eliminates a separate laboratory phase and extra appointments given for impressions, delivery, adjustments, and rebanding of the molars after removal. The molar attachments on the buccal side are free to be used for comprehensive fixed appliances, wire segments, intrusion arches, utility arches, or extraoral appliances. The expander is neither cumbersome nor uncomfortable and thus can be kept in place for retention and anchorage also, even when other procedures are being performed. Ciambotti et al. [19] did a comparative study between rapid palatal expanders and NiTi expanders for palatal expansion. They reported significant increases in palatal width (1.41 mm), intermolar width (4.76 mm), alveolar tipping (5.08 ), and molar tipping (6.08 ) in the rapid palatal expansion (RPE) group. Significant increases were found in palatal width (0.99 mm), intermolar width (6.26 mm), alveolar tipping (6.61 ), molar rotation (26.61 ), and molar tipping (11.69 ) in the NiTi group. 90

4 Radiographic evidence of midpalatal suture separation was found to be less obvious in the NiTi group than in the RPE group. The RPE appliance widened the palate more reliably, whereas the NiTi appliance tipped the molars buccally to a greater extent and caused more distal molar rotation. According to Donohue et al., [20] maxillary expansion using the quad helix (Q X ) appliance and NiTi expander was prospectively compared in 28 patients. The study models were used to measure the mean maxillary expansion efficacy (E max ) and the mean expansion rate (m max ) across the first molars and first premolars. Patient discomfort and cost factor were also considered. E max for Q X was 8.4+/ 0.7 and for NiTi expander was 7.8+/ 0.9 mm in the molar region and 5.1 mm and 5.9 mm in the premolar region. A significantly less discomfort was reported with NiTi on days 6 and 7 following the activation. They concluded that Q X and NiTi expanders are equally efficient maxillary expanders in terms of the magnitude of the expansion obtained and the expansion rate. Q X expansion appears to be significantly more controlled than the NiTi expanders, by virtue of significantly differential first molar premolar expansion efficacy and expansion rate. The Q X expansion rate appeared to be more predictable than NiTi. There was a significantly less discomfort with NiTi expanders. Q X is less expensive when compared to NiTi expanders. Paul et al. [21] did a study of NiTi expanders on a total of ten selected subjects. The effects of NiTi expanders were studied on models, occlusal radiographs, and lateral cephalograms. The duration of the treatment was on an average of 26 weeks along with the retention period. The changes in the maxillary intermolar width from a pretreatment range of mm to a posttreatment mean of 9.47+/ 1.73 mm were noted. The change of maxillary intercanine width pretreatment (2 4.5 mm) to a post-treatment of 3.45+/ 0.88 mm was noted. They concluded that a constant force of g exerted by the expander had definite effect in the growing age group which is indicated by an increase in intermolar width, maxillary intercanine width, and mandibular intermolar width. The ratio of the orthodontic to orthopedic effect by this appliance is 6:1. There was no relapse in any of the cases following 12 weeks of retention period. Ferrario et al. [22] analyzed the 6 month treatment effects of NiTi expander in 4 primary and 9 mixed dentition patients. All of the measurements were made on the mathematical models and radiographs. In all children, crossbite was completely corrected, and the increase in maxillary intermolar distance was in the range of mm. In all patients, except one, there was an increased maxillary inter-canine distance ( mm) always higher than or equivalent to the increase in intermolar distance. 6-month differences in anteroposterior dental arch dimensions ranged between 0 mm and 3 mm. Dental expansion was always higher than or corresponded to palatal expansion. They concluded that although the NiTi palatal expander may effectively correct dentoalveolar posterior crossbite, the increase in maxillary arch width is probably due to a combination of both orthopedic and orthodontic effects, especially in younger children. CONCLUSIONS The NiTi expander is a highly efficient slow maxillary expander. When compared with the Q X, significantly less discomfort was experienced by the patients who were treated with NiTi expanders. The Q X is more controlled, predictable, and cost-effective than NiTi palatal expander. The Nt expander provides a viable alternative to rapid palatal expanders for the correction of transverse discrepancies and eliminates a separate laboratory phase and extra appointments, since the buccal molar attachments are free for use. In younger children, the NiTi expander brings about the increase in intermolar width by a combination of skeletal and dentoalveolar effects. The expander is not cumbersome or uncomfortable and thus can be kept in place for retention and anchorage. REFERENCES 1. Ficarelli JP. A brief review of maxillary expansion. J Pedod 1978;3: Bell RA. A review of maxillary expansion in relation to rate of expansion and patient s age. Am J Orthod 1982;81: Harrison JE, Ashby D. Orthodontic treatment for posterior crossbites. Cochrane Database Syst Rev 2000;2:CD McNamara JA Jr, Baccetti T, Franchi L, Herberger TA. Rapid maxillary expansion followed by fixed appliances: A longterm evaluation of changes in arch dimensions. Angle Orthod 2003;73: Chang JY, McNamara JA Jr, Herberger TA. A longitudinal study of skeletal side effects induced by rapid maxillary expansion. Am J Orthod Dentofacial Orthop 1997;112: Timms DJ. An occlusal analysis of lateral maxillary expansion with midpalatal suture opening. Dent Pract Dent Rec 1968;18: Darendeliler MA, Strahm C, Joho JP. Light maxillary expansion forces with the magnetic expansion device. A preliminary investigation. Eur J Orthod 1994;16: Akkaya S, Lorenzon S, Uçem TT. Comparison of dental arch and arch perimeter changes between bonded rapid and slow maxillary expansion procedures. Eur J Orthod 1998;20: Capelozza Filho L, Cardoso Neto J, da Silva Filho OG, Ursi WJ. Non-surgically assisted rapid maxillary expansion in adults. Int J Adult Orthodon Orthognath Surg 1996;11: Hicks EP. Slow maxillary expansion. A clinical study of the skeletal versus dental response to low-magnitude force. Am J Orthod 1978;73: Mew J. Relapse following maxillary expansion. A study of twenty-five consecutive cases. Am J Orthod 1983;83: Proffit WR, Fields HW. Contemporary Orthodontics. 3 rd ed. St. Louis: Mosby; p Henry RJ. Slow maxillary expansion: A review of quad-helix 91

5 therapy during the transitional dentition. ASDC J Dent Child 1993;60: Akkaya S, Lorenzon S, Uçem TT. A comparison of sagittal and vertical effects between bonded rapid and slow maxillary expansion procedures. Eur J Orthod 1999;21: Malagola C, Caligiuri FM, Barbato E, Pachì F. Slow expansion of the upper jaw using quad-helix. Mondo Ortod 1988;13: Boysen B, La Cour K, Athanasiou AE, Gjessing PE. Threedimensional evaluation of dentoskeletal changes after posterior cross-bite correction by quad-helix or removable appliances. Br J Orthod 1992;19: Sandikçioğlu M, Hazar S. Skeletal and dental changes after maxillary expansion in the mixed dentition. Am J Orthod Dentofacial Orthop 1997;111: Marzban R, Nanda R. Slow maxillary expansion with nickel titanium. J Clin Ortho 1999;33: Ciambotti C, Ngan P, Durkee M, Kohli K, Kim H. A comparison of dental and dentoalveolar changes between rapid palatal expansion and nickel-titanium palatal expansion appliances. Am J Orthod Dentofacial Orthop 2001;119: Donohue VE, Marshman LA, Winchester LJ. A clinical comparison of the quahelix appliance and the nickel titanium (tandem loop) palatal expander a preliminary prospective investigation. Eur J Orthod 2004;26: Paul R, Kapoor T, Malhotra V, Krishna US, Bhatt SN. Efficacy of nickel titanium palatal expanders. J Ind Orthod Soc 2011;45: Ferrario VF, Garattini G, Colombo A, Filippi V, Pozzoli S, Sforza C, et al. Quantitative effects of a nickel-titanium palatal expander on skeletal and dental structures in the primary and mixed dentition: A preliminary study. Eur J Orthod 2003;25: Dawes M. Evidence-based practice. In: Dawes M, Davies P, Gray A, Mant J, Seers K, Snowball R, editors. Evidence-Based Practice: A Primer for Health Care Professionals. New York: Churchill Livingstone; p Eccles M, Freemantle N, Mason J. Using systematic reviews in clinical practice guidelines. In: Egger M, Smith GD, Altman DG, editors. Systematic Reviews in Health Care: Meta- Analysis in Context. 2 nd ed. London: BMJ Books; p Egger M, Smith GD, Schneider M. Systematic reviews of observational studies. In: Egger M, Smith GD, Altman DG, editors. Systematic Reviews in Health Care: Meta-Analysis in Context. 2 nd ed, Vol London: BMJ Books; p Guyatt G, Haynes B, Jaeschke R, Cook D, Greenhalgh T, Meade M, et al. Introduction: The philosophy of evidencebased medicine. In: Guyatt G, Rennie D, editors. Users Guides to the Medical Literature: A Manual for Evidence-Based Practice. Chicago: AMA Press; p Arndt WV. Nickel titanium palatal expander. J Clin Orthod 1993;27: Source of support: Nil; Conflict of interest: None Declared 92