ROD OSTRAVA
Group 1 (conventional brackets) Group 2 (self-ligating brackets)
N Mean SD Median Min. Max. N Mean SD Median Min. Max.
LI
36 4.17 1.35 4.25 1.9 6.0 29 4.66 1.31 5.10 1.8 6.23-3
1 36 25.82 2.07 26.00 21.0 30.0 29 25.92 1.49 25.90 23.3 29.53-3
2 36 26.62 1.44 26.35 24.0 30.0 29 26.51 0.96 26.30 25.0 28.46-6
1 36 41.47 3.02 41.70 34.9 51.0 29 41.45 1.94 41.20 38.4 45.06-6
2 36 42.51 2.93 42.70 36.2 50.3 29 41.62 2.11 41.60 37.0 47.5RL
1 36 34.45 2.30 34.15 29.4 40.6 29 34.42 1.90 34.40 30.0 37.8RL
2 36 35.42 1.76 35.00 31.8 40.2 29 35.24 1.53 35.50 32.5 37.9LL
1 36 34.29 1.86 34.80 30.4 38.1 29 34.58 1.79 34.50 30.0 37.8LL
2 36 35.37 1.72 35.15 32.0 39.5 29 35.30 1.42 35.30 32.8 38.91:ML
1 36 92.69 4.45 93.00 79.0 99.0 29 92.69 4.81 93.00 81.0 100.01:ML
2 36 96.86 4.04 97.00 85.0 102.0 29 96.05 4.70 97.00 85.0 103.01-APo
1 36 0.68 1.63 1.00 -4.0 3.0 29 0.88 1.47 1.00 -3.0 3.01-APo
2 36 2.44 1.51 2.75 -1.5 5.0 29 2.28 1.53 2.00 -1.0 5.0Age
36 15.55 3.96 13.83 11.6 25.0 29 14.83 3.11 13.78 10.8 23.5Time
36 117.72 37.96 122.00 49.0 201.0 29 137.41 49.67 147.00 32.0 226.0Tab. 1: MeÏrÏene velicÏiny ve skupinaÂch 1 a 2 Tab. 1: Measurements in Group 1 and Group 2
3-3 6-6 RL LL 1:ML 1-APo
mean SD p mean SD p mean SD p mean SD p mean SD p mean SD p
Group 1 (conventional brackets) 0.80 1.44 1.04 1.48 0.97 1.81 1.08 1.46 4.17 1.68 1.76 0.74 Group 2 (self-ligating brackets) 0.59 1.08 0.86 0.17 1.07 0.013* 0.82 1.74 0.83 0.72 1.28 0.92 3.36 2.32 0.21 1.40 1.12 0.28
Tab. 2: ZmeÏny velicÏi n beÏhem leÂcÏby a test rozdõÂlu meziskupinami
meÏrneÏ zveÏtsÏila o 0,97 mm a deÂlka leve strany dolnõÂho zubnõÂho oblouku o 1,08 mm. BeÏhem leÂcÏby dosÏlo k pro- truzidolnõÂchstrÏednõÂchrÏezaÂkuÊ pruÊmeÏrneÏo4,17° akpruÊ- meÏrne zmeÏneÏ postavenõ dolnõÂch strÏednõÂch rÏezaÂkuÊ vuÊcÏi linii APo o 1,76 mm.
Ve skupineÏ 2 byla pruÊmeÏrna expanze mezisÏpi cÏaÂ- kove vzdaÂlenosti0,59 mm, pruÊmeÏrna expanze mezi- molaÂrove vzdaÂlenostipouze 0,17 mm. DeÂlka prave strany dolnõÂho zubnõÂho oblouku se pruÊmeÏrneÏ zveÏtsÏi la o 0,82 mm a deÂlka leve strany dolnõÂho zubnõÂho oblouku o 0,72 mm. BeÏhem leÂcÏby dosÏlo k protruzidolnõÂch strÏednõÂch rÏezaÂkuÊ pruÊmeÏrneÏ o 3,36° a k pruÊmeÏrne zmeÏneÏ postavenõ dolnõÂch strÏednõÂch rÏezaÂkuÊ vuÊcÏi linii APo o 1,40 mm.
RozdõÂly velicÏin mezi skupinami byly naÂsledneÏ ote- stovaÂny neparametrickyÂm Mann-WhitneyovyÂm te- stem (Tab. 2), vzhledem k negaussovskeÂmu rozlozÏenõ neÏkteryÂch velicÏin. Statisticky vyÂznamny rozdõÂl (na hla- dineÏ vyÂznamnosti0,05) byl zjisÏteÏn pouze u velicÏi ny mezimolaÂrova vzdaÂlenost (6-6). OstatnõÂrozdõÂly v jedno- tlivyÂch velicÏi naÂch nejsou statisticky vyÂznamneÂ.
BeÏhem leÂcÏby dolnõÂm fixnõÂm aparaÂtem byla u obou skupin meÏrÏena deÂlka nivelizacÏnõ faÂze ve dnech. Ve sku- pineÏ 1 trvala nivelizace pruÊmeÏrneÏ 117,7 dnuÊ (tj. 3,9 meÏ- sõÂcuÊ), ve skupineÏ 2 pruÊmeÏrneÏ 137,4 dnuÊ (tj. 4,6 meÏsõÂcuÊ). Pro srovnaÂnõ deÂlky nivelizacÏnõ faÂze meziskupinamibyl pouzÏit Log Rank test. Hladina vyÂznamnostitestu je 0,024, cozÏ je mensÏõ nezÏ zvolena hladina vyÂznamnosti 0,05. RozdõÂl deÂlky nivelizacÏnõ faÂze meziskupinamibyl statisticky vyÂznamnyÂ. U skupiny 1 leÂcÏene konvencÏnõÂmi zaÂmky byla prokaÂzaÂna kratsÏõ deÂlka nivelizacÏnõ faÂze.
Pro srovnaÂnõÂ rychlosti nivelizace mezi skupinami byla pouzÏita Kaplan-Meierova analyÂza prÏezÏõÂvaÂnõÂ (Obr. 4).
(1:ML) before the treatment was 92.69°, and after the treatment finished 96.05°(Table 1).
The differences were calculated from the values of parameters measured before and after the treatment (Tab.2). In Group 1 the mean expansion of intercanine distance was 0.80 mm, the mean expansion of inter- molar distance 1.04 mm. The length of the right side of the lower dental arch increased by 0.97 mm on ave- rage, and the length of the left side by 1.08 mm. During the therapy lower central incisors protruded by 4.17° on the average, and the position of lower central inci- sors to APo line changed by 1.76 mm on the average. In Group 2 the mean expansion of intercanine di- stance was 0.59 mm, the mean expansion of intermo- lar distance was only 0.17 mm. The length of the right side of the lower dental arch increased by 0.82 mm on average, and the length of the left side by 0.72 mm. Du- ring the therapy lower central incisors protruded by 3.36° on average, and the position of lower central in- cisors to APo line changed by 1.40 mm on average.
The differences of parameters between the groups were then assessed with non-parametric Mann-Whit- ney test (Tab.2) as some parameters showed non- Gaussian distribution. Statistically significant diffe- rence (the level of significance of 0.05) was found only in intermolar distance (6-6). Other differences are not statistically significant.
During the treatment with fixed orthodontic ap- pliance in the mandible, duration of nivelization phase was measured (in days) in both groups. In Group 1 the phase took 117.7 days on average (i.e. 3.9 months), in Group 2 it took 137.4 days (i.e. 4.6 months). To com- pare the length of nivelization phase Log Rank test was applied. The level of significance for the test is
Obr. 4 KumulativnõÂ pravdeÏpodobnost doby nivelizace u obou skupin Fig. 4: Cummulative probability of nivelization phase duration in both groups
Obr. 5: Bodovy diagram LI a deÂlky nivelizacÏnõ faÂze s prolozÏenyÂmire- gresnõÂmiprÏõÂmkami
Fig. 5: Scatter diagram of LI and of nivelization phase duration with straight regression lines
0.024, i.e. less than the adopted level of significance (0.05). The difference between both groups was stati- stically significant. In Group 1 (treated with conventio- nal brackets) the phase was shorter.
To compare the speed of nivelization between the groups, Kaplan-Meier survival analysis was used (Fig. 4).
To evaluate the relationship between the value of Little Index and the length of nivelization phase serial Spearman's rank correlation coefficient was used (Tab.3). Correlation coefficients proved statistically significant dependency between the two parameters in both groups. However, the difference between cor- relations is not statistically significant.
To visualize the parameters of relationship the scat- tergram was used (Fig.5). Straight lines, scattered with points of both groups, are straight lines of linear re- gression. The parameters of relationship between the groups are not significantly different.
Discussion
In literature we can find different opinions on treat- ment efficiency, speed of nivelization and expansion in dental arch in patients with self-ligating brackets. Works by Harradine [10] and Eberting [11] report shor- ter length of treatment (by several months) and less time spent in orthodontic practices in case of patients with self-ligating brackets. However, recent studies do not find a difference in the length of treatment or speed of nivelization between patients treated with conven- tional brackets and those using self-ligating brackets. Miles [12, 14] focused on the effectiveness of self-liga- ting brackets SmartClip (3M Unitek) and Damon 2 (Ormco) in comparison with conventional brackets Vic- tory (3M Unitek). He concludes that the treatment of crowding by means of self-ligating brackets is not more effective than the treatment using conventional brackets. Fleming et al. [1] dealt with the speed of nivelization in 60 patients (without extractions) treated with self-ligating brackets SmartClip (3M Unitek) and conventional brac- kets Victory (3M Unitek). The mean value of LI was below 3 mm in both groups. They found out that the nivelization phase was almost identical in both groups (in fact in the group with self-ligating brackets it took a little longer (by a week on average)). Pandis et al. [18] compared the speed of nivelization in patients with self-ligating brac- kets Damon 2 (Ormco) and conventional brackets Mic- roarch (GAC). The mean value of LI was 5.3 mm in the control group, while in the group treated with self-ligating brackets it was 5.5 mm. In patients with LI below 5 mm the treatment with Damon 2 brackets took a little less time. In patients with LI over 5 mm no differences were found for this parameter. Pandis et al. focused also on expansion in the lower dental arch and protrusion of lower incisors. In Pro hodnocenõÂ vztahu mezivelikostõÂ LI a deÂlkou ni-
velizacÏnõ faÂze byl pouzÏit porÏadovy SpearmanuÊv kore- lacÏnõ koeficient (Tab. 3). KorelacÏnõ koeficienty prokaÂ- zaly, zÏe existuje statisticky vyÂznamna zaÂvislost LI a deÂlky nivelizacÏnõ faÂze v obou skupinaÂch. Mezikorela- cemi nenõ statisticky vyÂznamny rozdõÂl.
Pro zobrazenõ vztahu velicÏin byl pouzÏit bodovy dia- gram sledovanyÂch velicÏin (Obr. 5). PrÏõÂmky, prolozÏene body obou skupin, jsou prÏõÂmky lineaÂrnõ regrese. ZaÂvi - slost velicÏin se mezi skupinami statisticky vyÂznamneÏ nelisÏõÂ.
Diskuse
SdeÏlenõÂ v zahranicÏnõÂ literaturÏe o efektiviteÏ leÂcÏby, ry- chlosti nivelizace a expanzi v zubnõÂm oblouku u pa- cientuÊ se samoligujõÂcõÂmi zaÂmky se ruÊznõÂ. PrÏestozÏe praÂce Harradina [10] a Ebertinga [11] referujõÂ o zkraÂcenõÂ doby leÂcÏby o neÏkolik meÏsõÂcuÊ a snõÂzÏenõÂ pocÏtu ordinacÏ- nõÂch naÂvsÏteÏv u pacientuÊ se samoligujõÂcõÂmi zaÂmky, no- veÏjsÏõÂ studie nenachaÂzejõÂ rozdõÂl v dobeÏ leÂcÏby aniv ry- chlosti nivelizace mezi pacientys konvencÏnõÂmia samo- ligujõÂcõÂmi zaÂmky.
Miles [12, 14] se ve dvou studiõÂch zabyÂval efektivitou samoligujõÂcõÂch zaÂmkuÊ SmartClip (3M Unitek) a Damon 2 (Ormco) v porovnaÂnõ s konvencÏnõÂmizaÂmky Victory (3M Unitek). DosÏel k zaÂveÏru, zÏe leÂcÏba steÏsnaÂnõ pomocõ samoligujõÂcõÂch zaÂmkuÊ nenõ efektivneÏjsÏõ nezÏlileÂcÏba kon- vencÏnõÂmizaÂmky. Fleming a kol. [1] se zabyÂvalirychlostõ nivelizace u 60 neextrakcÏnõÂch pacientuÊ leÂcÏenyÂch samoligujõÂcõÂmi zaÂmky SmartClip (3M Unitek) a kon- vencÏnõÂmizaÂmky Victory (3M Unitek). PruÊmeÏrny LittluÊv index byl u obou skupin do 3 mm. Zjistili, zÏe doba nive- lizace je u obou skupin teÂmeÏrÏ shodnaÂ, respektive u sku- piny se samoligujõÂcõÂmi zaÂmky mõÂrneÏ delsÏõ (v pruÊmeÏru o tyÂden). Pandis a kol. [18] porovnaÂvali rychlost niveli- zace u pacientuÊ se samoligujõÂcõÂmi zaÂmky Damon 2 (Ormco) a konvencÏnõÂmizaÂmky Microarch (GAC). PruÊ- meÏrny LI byl 5,3 mm u kontrolnõ skupiny a 5,5 mm u skupiny se samoligujõÂcõÂmi zaÂmky. U pacientuÊ s LI do 5 mm byla leÂcÏba rychlejsÏõ s Damon 2 zaÂmky, u pa- cientuÊ s LI veÏtsÏõÂm nezÏ 5 mm nenasÏel rozdõÂl meziskupi- namiv dobeÏ nivelizace. Pandis a kol. se take zabyÂvali expanzõ v dolnõÂm zubnõÂm oblouku a protruzõ dolnõÂch rÏe- zaÂkuÊ. Pro skupinu se samoligujõÂcõÂmi zaÂmky pouzÏõÂvali
correlation coefficient
difference p
Group 1 (conventional brackets) 0.52*
Group 2 (self-ligating brackets) 0.60* p=0.64
Tab. 3: KorelacÏnõÂ koeficienty mezi LI a deÂlkou nivelizacÏnõÂ faÂze (Time) Tab. 3: Correlation coefficients - LI and the duration of nivelization phase (Time)
the group with self-ligating brackets they used CuNiTi ar- ches (Ormco) according to the instructions written for the Damon system. The difference regarding expansion of in- termolar distance between the group using self-ligating brackets (the mean value of expansion = 2 mm) and the control group (the mean value of expansion = 0.4 mm) was statistically significant. However, the difference of expansion of intercanine distance and in lower incisors protrusion was not statistically significant. Fleming et al. [1] also found statistically significant difference regarding expansion of intermolar distance in patients with self-li- gating brackets (the mean values of expansion being 1.41 mm for the group with self-ligating brackets, and 0.5 mm in case of the control group).
In terms of parameters measured in models and la- teral cephalograms the only statistically significant dif- ference found in our study was in the expansion of in- termolar distance (6-6). In Group 1 (conventional brac- kets) the mean value of expansion was 1.04 mm, in Group 2 (self-ligating brackets) the value was 0.17 mm. The result does not correspond to earlier studies where the statistically significant expansion of inter- molar distance was found in the group with self-liga- ting brackets [1, 18]. Increased expansion of intermolar distance in Group 1 may be due to the inclination of molars prior to treatment. However, this is just an as- sumption which was not proven by measurements.
Another parameter monitored in our study was the speed of nivelization. The mean length of nivelization phase was 118 days in the control group, and 137 days in the group with self-ligating brackets. The difference between the two groups was statistically significant. In patients treated with conventional brackets the phase took less time. Thus the effectiveness of self-ligating brac- kets was not proved. This corresponds to the results given in previous studies [1, 12, 14]. Statistical analysis proved that the dependency between LI and the length of niveliza- tion phase is statistically significant in both groups.
Conclusion
1. The treatment with self-ligating brackets did not result in statistically significant expansion of the lower dental arch.
2. The mean value of the change in the angle bet- ween lower incisors and the mandibular line was 4.17° in Group 1, and 3.36° in Group 2. The difference between the groups was not statistically significant.
3. Shorter phase of nivelization was proved in the group of patients treated with conventional brackets.
4. Relationship between the Little Irregularity Index and the duration of nivelization phase was statistically significant in both groups.
Authors have no commercial, proprietary or financial interest in products or companies mentioned in the article.
CuNiTi oblouky (Ormco) dle doporucÏenõ manuaÂlu pro systeÂm Damon. Statisticky vyÂznamny byl rozdõÂl v expanzimezimolaÂrove vzdaÂlenostimeziskupinou se samoligujõÂcõÂmi zaÂmky (pruÊmeÏrna hodnota expanze 2 mm) a kontrolnõ skupinou (pruÊmeÏrna expanze 0,4 mm). RozdõÂl v expanzimezisÏpi cÏaÂkove vzdaÂlenosti a v protruzidolnõÂch rÏezaÂkuÊ mezi skupinami nebyl stati- sticky vyÂznamnyÂ. StejneÏ tak Fleming a kol. [1] nameÏrÏili statisticky vyÂznamny rozdõÂl v expanzimezimolaÂrove vzdaÂlenostiu pacientuÊ se samoligujõÂcõÂmi zaÂmky (pruÊ- meÏrna hodnota byla pro skupinu se samoligujõÂcõÂmi zaÂ- mky 1,41 mm, pro kontrolnõ skupinu 0,5 mm).
Z meÏrÏenyÂch velicÏin na modelu a bocÏnõÂm kefalome- trickeÂm snõÂmku byl v nasÏem sledovaneÂm souboru sta- tisticky vyÂznamny pouze rozdõÂl expanze mezimolaÂrove vzdaÂlenosti (6-6) mezi skupinami. PruÊmeÏrna hodnota expanze pro skupinu 1 s konvencÏnõÂmizaÂmky byla 1,04 mm, pro skupinu 2 se samoligujõÂcõÂmi zaÂmky 0,17 mm. VyÂsledek neodpovõÂda prÏedesÏlyÂm studiõÂm, kde u skupiny se samoligujõÂcõÂmi zaÂmky dosÏlo ke stati- sticky vyÂznamne expanzimezimolaÂrove vzdaÂlenosti [1, 18]. VeÏtsÏõ expanze mezimolaÂrove vzdaÂlenostiu sku- piny 1 mohla byÂt zpuÊsobena sklonem molaÂruÊ prÏed leÂcÏ- bou. Jedna se vsÏak o prÏedpoklad, ktery nebyl meÏrÏenõÂm oveÏrÏen.
DaÂle byla srovnaÂna rychlost nivelizace mezi skupi- nami. PruÊmeÏrna deÂlka nivelizacÏnõ faÂze byla u kontrolnõ skupiny (skupina 1) 118 dnuÊ, u skupiny se samoligujõÂ- cõÂmizaÂmky (skupina 2) 137 dnuÊ. RozdõÂl meziskupinami byl vyhodnocen jako statisticky vyÂznamnyÂ. U pacientuÊ leÂcÏenyÂch konvencÏnõÂmizaÂmky byla prokaÂzaÂna kratsÏõ deÂlka nivelizacÏnõ faÂze. VeÏtsÏõ efektivita samoligujõÂcõÂch zaÂmkuÊ se tedy nepotvrdila stejneÏ jako v prÏedesÏlyÂch studiõÂch [1, 12, 14]. Statisticka analyÂza take prokaÂzala zaÂvislost LI a deÂlky nivelizacÏnõ faÂze u obou skupin jako vyÂznamnou.
ZaÂveÏr
1. LeÂcÏba samoligujõÂcõÂmi zaÂmky nezpuÊsobovala sta- tisticky vyÂznamnou expanziv dolnõÂm zubnõÂm oblouku. 2. PruÊmeÏrna zmeÏna uÂhlu dolnõÂch rÏezaÂkuÊ k mandibu- laÂrnõ linii byla u 1. skupiny 4,17°, u 2. skupiny 3,36°. RozdõÂl mezi skupinami nenõ statisticky vyÂznamnyÂ.
3. KratsÏõÂ deÂlka nivelizacÏnõÂ faÂze byla prokaÂzaÂna u pa- cientuÊ leÂcÏenyÂch konvencÏnõÂmizaÂmky.
4. Byla zjisÏteÏna statisticky vyÂznamna zaÂvislost Lit- tleova indexu nepravidelnosti a deÂlky nivelizacÏnõ faÂze u obou skupin.
AutorÏi nemajõ komercÏnõÂ, vlastnicke nebo financÏnõ zaÂjmy na pro- duktech nebo spolecÏnostech popsanyÂch v tomto cÏlaÂnku.
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MUDr. Hana ZdarÏilovaÂ
Stomatologicka klinika FN u sv. Anny PekarÏska 53, 656 91 Brno