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Residents' journal review
RESIDENTS' JOURNAL REVIEW
ARTICLES FROM THE CURRENT ORTHODONTIC LITERATURE, SELECTED AND REVIEWED BY: RESIDENTS FROM THE GRADUATE ORTHODONTIC PROGRAM, UNIVERSITY OF WASHINGTON, SEATTLE Greg J. Huang, Chair, and Anne-Marie Bollen, Graduate Program Director Dan Grauer, Associate Editor for Residents' Journal Review Los Angeles, Calif
Nonsurgical maxillary expansion: a meta-analysis Zhou Y, Long H, Ye N, Xue J, Yang X, Liao L, et al. The effectiveness of non-surgical maxillary expansion: a meta-analysis. Eur J Orthod 2014;36:233-42.
I
s the decision between rapid maxillary expansion (RME) and slow maxillary expansion (SME) an important one when treatment planning for expansion? If so, which treatment modality is more effective for expansion? In this systematic review, the authors proposed to determine and compare the effectiveness of RME and SME using meta-analysis. This is the first meta-analysis to compare the 2 modalities. Fourteen studies were included in the quantitative synthesis. Four outcomes were considered (maxillary intermolar width, maxillary intercanine width, maxillary interpremolar width, and mandibular intermolar width) at 3 times (expansion, retention, and net change). The results of the metaanalysis indicate that both SME and RME are effective relative to the controls. SME is effective at expanding the maxillary arch, but its effect on mandibular intermolar width could not be determined. RME was found to be effective at expanding both the maxillary and mandibular arches. When comparing the effectiveness of the 2 expansion modalities, the authors concluded that SME is superior to RME in expanding maxillary intermolar width, whereas there was no difference between RME and SME in expansion of maxillary interpremolar and mandibular intermolar widths. However, when the results were evaluated carefully, it became apparent that this conclusion was largely based on the results of 1 heavily weighted study. Consequently, the conclusions from this meta-analysis must be viewed with caution. As the
140
authors themselves acknowledge, reliable methods and analogous treatment protocols are necessary to strengthen their findings. In addition, evaluating effectiveness based on the amount of expansion might not be justified, since the transverse needs of each patient differ. Future investigations could consider differentiating skeletal vs dental expansion by using 3-dimensional analysis and analogous treatment protocols. Reviewed by Blake B. Davis and Niousha Saghafi
Pulpectomy and root resorption during orthodontic tooth movement Kaku M, Sumi H, Shikata H, Kojima S, Motokawa M, Fujita T, et al. Effects of pulpectomy on the amount of root resorption during orthodontic tooth movement. J Endod 2014;40:372-8.
R
esearch shows that root resorption (RR) is associated with macrophage colony stimulating factor and receptor activator of nuclear factor kappa-b ligand (RANKL), which lead to odontoclast differentiation. Injured pulp cells produce macrophage colony stimulating factor and RANKL in response to forces, and it is hypothesized that “stretched” and “injured” pulpal cells will ultimately lead to apical RR. Also linked with inflammatory mediator production is calcium influx via a stretch-activated channel. These authors evaluated the production of macrophage colony stimulating factor/ RANKL/interleukin-1 beta/tumor necrosis factor alpha in response to tensile forces, stretch-activated channel inhibition, and differences in RR during tooth movement between pulpless and intact teeth. Pulp tissue was obtained and cultured on a membrane. The samples were subjected to forces, and experiments were performed that illustrated the effect of stretch-activated channel inhibition on mRNA expression of inflammatory factors. A split-mouth design was used in rats comparing RR between devitalized and vital molars. Experimental tensile forces led to increases in the amount of mRNA isolated with both increased duration and force levels, as well as blockage of calcium influx and reduced mRNA levels. In the rats, the control teeth showed more apical RR than did the devitalized teeth. These findings led the authors to state that light forces should be applied, and pulpal removal might be effective in patients with severe RR during tooth movement. One might argue that the experimental force application does not represent clinical forces or that the small difference in RR observed experimentally has little value considering
Residents' journal review
the magnitude of RR in severe clinical cases. Although these points can have some validity, this study could provide the pilot data for subsequent studies. Reviewed by Jantraveus Merritt and Mariana Muguerza
Gingival tissue transcriptomes identify distinct periodontitis phenotypes € n B, Guarnieri P, Kebschull M, Demmer RT, Gru Pavlidis P, Papapanou PN. Gingival tissue transcriptomes identify distinct periodontitis phenotypes. J Dent Res 2014;93:459-68.
A
ggressive and chronic periodontitis has a distinct pattern of bone destruction, progression rate, and age of onset; however, the pathobiology of the disease in these 2 classes of periodontitis is similar. Aggressive and chronic classes of periodontitis are primarily defined based on clinical evaluations of the disease. Kebschull et al sought to reclassify patients diagnosed with aggressive and chronic periodontitis according to their gingival tissue transcriptome, which is reasoned to have a more biologic foundation. This classification, driven by a molecular profile of diseased subjects, could lead to more effective treatment protocols for them. Gene array analysis was performed on 241 gingival biopsies from 120 patients, and 2 new clusters of these patients were determined based on the transcriptome data. Patient classification based on the molecular profile was significantly different from the conventional classification (adjusted Rand index 5 0.0143). Clinical assessments of the new clusters suggested that periodontal health parameters including plaque index, bleeding on probing, probing depth, and clinical attachment levels were uniformly exacerbated in cluster 2 of these patients, whereas this trend was not detected in patients classified conventionally. For example, plaque index and bleeding on probing were similar in patients with aggressive and chronic periodontitis. Additionally, microbial and immunologic profile analyses of these patients showed different traits, based on the conventional or the new classification of the disease. These results suggest that the molecular profile of patients with periodontitis might represent a better picture of the disease compared with the conventional classification. Development of a new molecular-based classification of periodontitis seems promising, yet a life-course cohort study to examine molecular profiles
141
of patients at the onset and during the development of periodontitis is required to this end. Reviewed by Roozbeh Khosravi and Maria Nart
Mandibular setback surgery with and without presurgical orthodontics Kim CS, Lee SC, Kyung HM, Park HS, Kwon TG. Stability of mandibular setback surgery with and without presurgical orthodontics. J Oral Maxillofac Surg 2014;72:779-87.
A
recent variation in surgical orthodontics has been the popularization of the “surgery-first” technique. The proposed benefits of performing orthognathic surgery before orthodontic tooth movement include (1) decreased postsurgical treatment time associated with the rapid acceleratory phenomenon, and (2) elimination of the presurgical orthodontic decompensation period, which temporarily worsens the facial profile. Skeletal stability and relapse potential, however, must be considered before attempting a surgery-first approach. This retrospective cohort study included 61 mandibular prognathic patients who underwent bilateral sagittal split osteotomy setback of the mandible. Thirty-eight patients were treated with presurgical orthodontics and conventional surgery, and 23 patients had surgery first with no presurgical orthodontics. All surgery-first patients had mild to moderate crowding with adequate inclination of the anterior teeth, 3 stable occlusal stops, minimal or no transverse discrepancy, and a normal curve of Spee. Baseline variables, including degree of mandibular prognathism, were similar for both groups. Lateral cephalograms taken preoperatively, immediately postoperatively, and at debond were analyzed to determine the difference in stability of the mandibular landmarks. Anteroposterior relapse at B-point was significantly increased in the surgery-first group (2.4 mm; range, 0.1-6.1 mm) compared with the conventional-surgery group (1.6 mm; range, 0.0-4.9 mm). Vertical relapse at B-point was approximately 1 mm in both groups. Relapse greater than 3 mm at B-point occurred more frequently in the surgery-first group, whereas relapse of less than 1.5 mm was more common in the conventional-surgery group. This concise study shows that the surgery-first approach for treating mandibular prognathism with bilateral sagittal split osteotomy setback is less stable than conventional orthognathic surgery with presurgical orthodontics. The authors suggest that although a surgery-first approach decreases overall treatment time,
American Journal of Orthodontics and Dentofacial Orthopedics
August 2014 Vol 146 Issue 2
Residents' journal review
142
postsurgical occlusal instability might negatively influence the long-term position of the mandible. Reviewed by Soleil Roberts and Keyvan Sohrabi
Corticotomies for mandibular incisor decompensation in Class III patients Wang B, Shen G, Fang B, Yu H, Wu Y, Sun L. Augmented corticotomy-assisted surgical orthodontics decompensates lower incisors in class III malocclusion patients. J Oral Maxillofac Surg 2014;72:596-602.
P
atients with a severe Class III malocclusion often require combined orthodontic and orthognathic treatment for ideal correction. The cortical walls surrounding the mandibular incisors limit the dental movement that can be achieved, often leading to iatrogenic sequelae such as root resorption, bony dehiscences, and gingival recession. The purpose of this study was to evaluate the periodontal changes associated with augmented corticotomy-assisted surgical orthodontics in decompensating the mandibular incisors in patients undergoing orthognathic surgical correction for Class III malocclusion. In this case series, cone-beam computed tomography imaging and lateral
August 2014 Vol 146 Issue 2
cephalograms were obtained for 8 subjects before the start of orthodontic treatment (T0), after presurgical orthodontics (T1), and at appliance removal (T2). Measurements for analysis included root length, vertical alveolar bone level on the labial and lingual surfaces, alveolar bone thickness at the apex on the labial and lingual surfaces, and angulation of the mandibular incisors to the mandibular plane (IMPA). Orthodontic treatment was initiated and followed by corticotomies and placement of deproteinized bovine bone with a collagen membrane. These authors found no significant changes in root length throughout treatment. Labial alveolar bone thickness and IMPA increased presurgically and remained stable from T1 to T2. Vertical alveolar bone level on both the labial and lingual surfaces initially increased from T0 to T1, but decreased postsurgically. Lingual alveolar bone thickness decreased from T0 to T1, but increased from T1 to T2. These results suggest that corticotomyassisted surgical orthodontics can aid in decompensating the mandibular incisors in patients with Class III malocclusion, while minimizing periodontal sideeffects. Future studies involving larger sample sizes, well-matched control groups, and long-term followups would be helpful in supporting the findings from this study. Reviewed by Susan Kim and Matthew Stout
American Journal of Orthodontics and Dentofacial Orthopedics
ARTICLES FROM THE CURRENT ORTHODONTIC LITERATURE, SELECTED AND REVIEWED BY: RESIDENTS FROM THE GRADUATE ORTHODONTIC PROGRAM, UNIVERSITY OF WASHINGTON, SEATTLE Greg J. Huang, Chair, and Anne-Marie Bollen, Graduate Program Director Dan Grauer, Associate Editor for Residents' Journal Review Los Angeles, Calif
Nonsurgical maxillary expansion: a meta-analysis Zhou Y, Long H, Ye N, Xue J, Yang X, Liao L, et al. The effectiveness of non-surgical maxillary expansion: a meta-analysis. Eur J Orthod 2014;36:233-42.
I
s the decision between rapid maxillary expansion (RME) and slow maxillary expansion (SME) an important one when treatment planning for expansion? If so, which treatment modality is more effective for expansion? In this systematic review, the authors proposed to determine and compare the effectiveness of RME and SME using meta-analysis. This is the first meta-analysis to compare the 2 modalities. Fourteen studies were included in the quantitative synthesis. Four outcomes were considered (maxillary intermolar width, maxillary intercanine width, maxillary interpremolar width, and mandibular intermolar width) at 3 times (expansion, retention, and net change). The results of the metaanalysis indicate that both SME and RME are effective relative to the controls. SME is effective at expanding the maxillary arch, but its effect on mandibular intermolar width could not be determined. RME was found to be effective at expanding both the maxillary and mandibular arches. When comparing the effectiveness of the 2 expansion modalities, the authors concluded that SME is superior to RME in expanding maxillary intermolar width, whereas there was no difference between RME and SME in expansion of maxillary interpremolar and mandibular intermolar widths. However, when the results were evaluated carefully, it became apparent that this conclusion was largely based on the results of 1 heavily weighted study. Consequently, the conclusions from this meta-analysis must be viewed with caution. As the
140
authors themselves acknowledge, reliable methods and analogous treatment protocols are necessary to strengthen their findings. In addition, evaluating effectiveness based on the amount of expansion might not be justified, since the transverse needs of each patient differ. Future investigations could consider differentiating skeletal vs dental expansion by using 3-dimensional analysis and analogous treatment protocols. Reviewed by Blake B. Davis and Niousha Saghafi
Pulpectomy and root resorption during orthodontic tooth movement Kaku M, Sumi H, Shikata H, Kojima S, Motokawa M, Fujita T, et al. Effects of pulpectomy on the amount of root resorption during orthodontic tooth movement. J Endod 2014;40:372-8.
R
esearch shows that root resorption (RR) is associated with macrophage colony stimulating factor and receptor activator of nuclear factor kappa-b ligand (RANKL), which lead to odontoclast differentiation. Injured pulp cells produce macrophage colony stimulating factor and RANKL in response to forces, and it is hypothesized that “stretched” and “injured” pulpal cells will ultimately lead to apical RR. Also linked with inflammatory mediator production is calcium influx via a stretch-activated channel. These authors evaluated the production of macrophage colony stimulating factor/ RANKL/interleukin-1 beta/tumor necrosis factor alpha in response to tensile forces, stretch-activated channel inhibition, and differences in RR during tooth movement between pulpless and intact teeth. Pulp tissue was obtained and cultured on a membrane. The samples were subjected to forces, and experiments were performed that illustrated the effect of stretch-activated channel inhibition on mRNA expression of inflammatory factors. A split-mouth design was used in rats comparing RR between devitalized and vital molars. Experimental tensile forces led to increases in the amount of mRNA isolated with both increased duration and force levels, as well as blockage of calcium influx and reduced mRNA levels. In the rats, the control teeth showed more apical RR than did the devitalized teeth. These findings led the authors to state that light forces should be applied, and pulpal removal might be effective in patients with severe RR during tooth movement. One might argue that the experimental force application does not represent clinical forces or that the small difference in RR observed experimentally has little value considering
Residents' journal review
the magnitude of RR in severe clinical cases. Although these points can have some validity, this study could provide the pilot data for subsequent studies. Reviewed by Jantraveus Merritt and Mariana Muguerza
Gingival tissue transcriptomes identify distinct periodontitis phenotypes € n B, Guarnieri P, Kebschull M, Demmer RT, Gru Pavlidis P, Papapanou PN. Gingival tissue transcriptomes identify distinct periodontitis phenotypes. J Dent Res 2014;93:459-68.
A
ggressive and chronic periodontitis has a distinct pattern of bone destruction, progression rate, and age of onset; however, the pathobiology of the disease in these 2 classes of periodontitis is similar. Aggressive and chronic classes of periodontitis are primarily defined based on clinical evaluations of the disease. Kebschull et al sought to reclassify patients diagnosed with aggressive and chronic periodontitis according to their gingival tissue transcriptome, which is reasoned to have a more biologic foundation. This classification, driven by a molecular profile of diseased subjects, could lead to more effective treatment protocols for them. Gene array analysis was performed on 241 gingival biopsies from 120 patients, and 2 new clusters of these patients were determined based on the transcriptome data. Patient classification based on the molecular profile was significantly different from the conventional classification (adjusted Rand index 5 0.0143). Clinical assessments of the new clusters suggested that periodontal health parameters including plaque index, bleeding on probing, probing depth, and clinical attachment levels were uniformly exacerbated in cluster 2 of these patients, whereas this trend was not detected in patients classified conventionally. For example, plaque index and bleeding on probing were similar in patients with aggressive and chronic periodontitis. Additionally, microbial and immunologic profile analyses of these patients showed different traits, based on the conventional or the new classification of the disease. These results suggest that the molecular profile of patients with periodontitis might represent a better picture of the disease compared with the conventional classification. Development of a new molecular-based classification of periodontitis seems promising, yet a life-course cohort study to examine molecular profiles
141
of patients at the onset and during the development of periodontitis is required to this end. Reviewed by Roozbeh Khosravi and Maria Nart
Mandibular setback surgery with and without presurgical orthodontics Kim CS, Lee SC, Kyung HM, Park HS, Kwon TG. Stability of mandibular setback surgery with and without presurgical orthodontics. J Oral Maxillofac Surg 2014;72:779-87.
A
recent variation in surgical orthodontics has been the popularization of the “surgery-first” technique. The proposed benefits of performing orthognathic surgery before orthodontic tooth movement include (1) decreased postsurgical treatment time associated with the rapid acceleratory phenomenon, and (2) elimination of the presurgical orthodontic decompensation period, which temporarily worsens the facial profile. Skeletal stability and relapse potential, however, must be considered before attempting a surgery-first approach. This retrospective cohort study included 61 mandibular prognathic patients who underwent bilateral sagittal split osteotomy setback of the mandible. Thirty-eight patients were treated with presurgical orthodontics and conventional surgery, and 23 patients had surgery first with no presurgical orthodontics. All surgery-first patients had mild to moderate crowding with adequate inclination of the anterior teeth, 3 stable occlusal stops, minimal or no transverse discrepancy, and a normal curve of Spee. Baseline variables, including degree of mandibular prognathism, were similar for both groups. Lateral cephalograms taken preoperatively, immediately postoperatively, and at debond were analyzed to determine the difference in stability of the mandibular landmarks. Anteroposterior relapse at B-point was significantly increased in the surgery-first group (2.4 mm; range, 0.1-6.1 mm) compared with the conventional-surgery group (1.6 mm; range, 0.0-4.9 mm). Vertical relapse at B-point was approximately 1 mm in both groups. Relapse greater than 3 mm at B-point occurred more frequently in the surgery-first group, whereas relapse of less than 1.5 mm was more common in the conventional-surgery group. This concise study shows that the surgery-first approach for treating mandibular prognathism with bilateral sagittal split osteotomy setback is less stable than conventional orthognathic surgery with presurgical orthodontics. The authors suggest that although a surgery-first approach decreases overall treatment time,
American Journal of Orthodontics and Dentofacial Orthopedics
August 2014 Vol 146 Issue 2
Residents' journal review
142
postsurgical occlusal instability might negatively influence the long-term position of the mandible. Reviewed by Soleil Roberts and Keyvan Sohrabi
Corticotomies for mandibular incisor decompensation in Class III patients Wang B, Shen G, Fang B, Yu H, Wu Y, Sun L. Augmented corticotomy-assisted surgical orthodontics decompensates lower incisors in class III malocclusion patients. J Oral Maxillofac Surg 2014;72:596-602.
P
atients with a severe Class III malocclusion often require combined orthodontic and orthognathic treatment for ideal correction. The cortical walls surrounding the mandibular incisors limit the dental movement that can be achieved, often leading to iatrogenic sequelae such as root resorption, bony dehiscences, and gingival recession. The purpose of this study was to evaluate the periodontal changes associated with augmented corticotomy-assisted surgical orthodontics in decompensating the mandibular incisors in patients undergoing orthognathic surgical correction for Class III malocclusion. In this case series, cone-beam computed tomography imaging and lateral
August 2014 Vol 146 Issue 2
cephalograms were obtained for 8 subjects before the start of orthodontic treatment (T0), after presurgical orthodontics (T1), and at appliance removal (T2). Measurements for analysis included root length, vertical alveolar bone level on the labial and lingual surfaces, alveolar bone thickness at the apex on the labial and lingual surfaces, and angulation of the mandibular incisors to the mandibular plane (IMPA). Orthodontic treatment was initiated and followed by corticotomies and placement of deproteinized bovine bone with a collagen membrane. These authors found no significant changes in root length throughout treatment. Labial alveolar bone thickness and IMPA increased presurgically and remained stable from T1 to T2. Vertical alveolar bone level on both the labial and lingual surfaces initially increased from T0 to T1, but decreased postsurgically. Lingual alveolar bone thickness decreased from T0 to T1, but increased from T1 to T2. These results suggest that corticotomyassisted surgical orthodontics can aid in decompensating the mandibular incisors in patients with Class III malocclusion, while minimizing periodontal sideeffects. Future studies involving larger sample sizes, well-matched control groups, and long-term followups would be helpful in supporting the findings from this study. Reviewed by Susan Kim and Matthew Stout
American Journal of Orthodontics and Dentofacial Orthopedics