The efficacy of a plasma arc light in orthodontic bonding: a randomized controlled clinical trial

Objective: To evaluate the clinical performance of a plasma arc light (Ortho LITE, 3M Unitek, Monrovia, CA, USA) against a conventional tungsten-quartz halogen curing light (Visilux 2, 3M Unitek, Monrovia, CA, USA) for direct orthodontic bonding. Design: A single centre prospective randomized controlled clinical trial. Setting: The Orthodontic Department at St Luke's Hospital, Bradford, UK. Subjects and methods: Forty-three consecutive patients requiring fixed appliances from the orthodontic waiting list. A split mouth technique was adopted; with quadrants randomly assigned to either the plasma arc light or the conventional halogen curing light and bonded directly with APC pre-adjusted edgewise brackets (3M Unitek, Monrovia, CA, USA). Main outcome measure: Bracket failures. Secondary outcome measures: Time taken to bond-up the appliances, patient sensitivity or discomfort during curing and time to replace failed brackets were investigated. Results: No statistically significant difference in bracket failure rates over the full course of treatment was found between the plasma arc light (6.7%; 95% CI 4.5-10.0) and the halogen curing light (9.5%; 95% CI 6.8-13.1). There was no statistically significant difference in bracket survival times. The bond-up times were typically reduced by 204 seconds per patient with the plasma arc light. There were no differences in patient reported sensitivity or discomfort or rebond times. Conclusion: The plasma arc light is a viable clinical alternative to the conventional halogen curing light with benefits for both the clinician and patient due to reduced bonding times.     

Plasma arc curing lights for orthodontic bonding

Xenon plasma arc lights were introduced recently for light-cured orthodontic bonding. Compared with a conventional tungsten-quartz-halogen light source, these high-intensity lights promise a dramatic reduction in curing time. The purpose of this in vitro investigation was to evaluate bond strength with 2 commercially available plasma arc lights and reduced curing intervals. Brackets were bonded to 150 extracted human teeth (75 premolars, 75 incisors) with a composite adhesive. Intervals of 2 and 6 seconds were used for curing with the plasma arc lights; a control group was bonded with a halogen light source and 20 seconds of light exposure per bracket. Bond strength testing was performed with a universal testing machine. A substantial reduction in curing time was possible with both plasma arc units. Significantly lower bond strength values were found for premolar brackets bonded with plasma arc curing lights and the shortest curing interval of 2 seconds compared with the longer curing time of 6 seconds or the standard curing time with the halogen light. Although 2 seconds of curing might be adequate to achieve acceptable bond strength values for the incisors, the Weibull analysis indicated a higher probability of bond failure for premolar brackets in particular. Six seconds of curing time is recommended for bonding stainless steel brackets with xenon plasma arc light sources.     

Plasma arc curing of ceramic brackets: an evaluation of shear bond strength and debonding characteristics.

The aim of this in vitro investigation was to evaluate bond strength and debonding characteristics when a xenon plasma arc curing light is used to bond polycrystalline and monocrystalline ceramic brackets. Brackets were bonded to 240 extracted bovine mandibular incisors with a composite adhesive. Curing intervals of 1, 3, and 6 seconds were chosen for curing with the plasma arc light, and the control group was cured at 10 seconds per bracket with a conventional halogen light. Debonding was performed on a universal testing machine and according to the bracket manufacturers' recommendations. Both the polycrystalline and the monocrystalline brackets consistently debonded at the bracket-adhesive interface, regardless of debonding method, curing interval, or curing light. No enamel fractures were observed after debonding. Bracket fractures were rare and did not affect debonding. Bond strength was significantly higher for the monocrystalline brackets (P <.0001): mean shear bond strength ranged between 9.68 +/- 2.17 MPa (plasma arc curing light, 1 sec curing interval) and 10.73 +/- 3.22 MPa (halogen light, 10 sec curing interval) for the polycrystalline brackets and between 19.85 +/- 2.97 MPa (plasma arc curing light, 1 sec curing interval) and 22.94 +/- 3.20 MPa (plasma arc curing light, 3 sec curing interval) for the monocrystalline brackets. Significant differences were also found for the curing methods used (P =.047). A curing interval of 3 seconds with the plasma arc curing light is recommended for both polycrystalline and monocrystalline ceramic brackets.     

LED vs halogen light-curing of adhesive-precoated brackets

OBJECTIVE: To test the hypothesis that bonding with a blue light-emitting diode (LED) curing unit produces no more failures in adhesive-precoated (APC) orthodontic brackets than bonding carried out by a conventional halogen lamp. MATERIALS AND METHODS: Sixty-five patients were selected for this randomized clinical trial, in which a total of 1152 stainless steel APC brackets were employed. In order to carry out a valid comparison of the bracket failure rate following use of each type of curing unit, each patient's mouth was divided into four quadrants. In 34 of the randomly selected patients, designated group A, the APC brackets of the right maxillary and left mandibular quadrants were bonded using a halogen light, while the remaining quadrants were treated with an LED curing unit. In the other 31 patients, designated group B, halogen light was used to cure the left maxillary and right mandibular quadrants, whereas the APC brackets in the remaining quadrants were bonded using an LED dental curing light. The bonding date, the type of light used for curing, and the date of any bracket failures over a mean period of 8.9 months were recorded for each bracket and, subsequently, the chi-square test, the Yates-corrected chi-square test, the Fisher exact test, Kaplan-Meier survival estimates, and the log-rank test were employed in statistical analyses of the results. RESULTS: No statistically significant difference in bond failure rate was found between APC brackets bonded with the halogen light-curing unit and those cured with LED light. However, significantly fewer bonding failures were noted in the maxillary arch (1.67%) than in the mandibular arch (4.35%) after each light-curing technique. CONCLUSIONS: The hypothesis cannot be rejected since use of an LED curing unit produces similar APC bracket failure rates to use of conventional halogen light, with the advantage of a far shorter curing time (10 seconds).     

The efficacy of a plasma arc light in orthodontic bonding: a randomized controlled clinical trial

Abstract

Objective: To evaluate the clinical performance of a plasma arc light (Ortho LITE, 3M Unitek, Monrovia, CA, USA) against a conventional tungsten–quartz halogen curing light (Visilux 2, 3M Unitek, Monrovia, CA, USA) for direct orthodontic bonding.

Design: A single centre prospective randomized controlled clinical trial.

Setting: The Orthodontic Department at St Luke’s Hospital, Bradford, UK.

Subjects and methods: Forty-three consecutive patients requiring fixed appliances from the orthodontic waiting list. A split mouth technique was adopted; with quadrants randomly assigned to either the plasma arc light or the conventional halogen curing light and bonded directly with APC pre-adjusted edgewise brackets (3M Unitek, Monrovia, CA, USA).

Main outcome measure: Bracket failures.

Secondary outcome measures: Time taken to bond-up the appliances, patient sensitivity or discomfort during curing and time to replace failed brackets were investigated.

Results: No statistically significant difference in bracket failure rates over the full course of treatment was found between the plasma arc light (6.7%; 95% CI 4.5–10.0) and the halogen curing light (9.5%; 95% CI 6.8–13.1). There was no statistically significant difference in bracket survival times. The bond-up times were typically reduced by 204 seconds per patient with the plasma arc light. There were no differences in patient reported sensitivity or discomfort or rebond times.

Conclusion: The plasma arc light is a viable clinical alternative to the conventional halogen curing light with benefits for both the clinician and patient due to reduced bonding times.     

Plasma arc versus halogen light-curing of adhesive-precoated orthodontic brackets: a 12-month clinical study of bond failures.

The purpose of this randomized clinical trial was to evaluate the performance of adhesive-precoated brackets cured with 2 different light-curing units (conventional halogen light and plasma arc light). Thirty patients treated with fixed appliances were included in the investigation. Each patient's mouth was divided by the split-mouth design into 4 quadrants. In 15 randomly selected patients, the maxillary left and mandibular right quadrants were cured with the halogen light, and the remaining quadrants were cured with the plasma arc light. In the other 15 patients, the quadrants were inverted. A total of 600 adhesive precoated stainless steel brackets were examined: 300 were cured with a conventional halogen light for 20 seconds, and the others were cured with the plasma arc light for 5 seconds. The number, cause, and date of bracket failures were recorded for each light-curing unit over 12 months. Statistical analysis was performed with the Fisher exact test, Kaplan-Meier survival estimates, and the log-rank test. No statistically significant differences in bond failure rates were found between the adhesive-precoated brackets cured with the halogen light and those cured with the plasma arc light; neither were any significant differences in performance found with each light-curing unit between the maxillary and mandibular arches. Plasma arc lights can be considered an advantageous alternative to conventional light curing, because they enable the clinician to reduce the curing time of adhesive-precoated orthodontic brackets without significantly affecting their bond failure rate.     

Comparison of the shear bond strength of brackets using the led curing light and plasma arc curing light: polymerization time

The xenon plasma arc curing light and the LED curing light have substantially decreased the time required for polymerizing a bracket bonding composite. However, the expense and size of the plasma arc curing light has limited its use. The LED curing light is less expensive, smaller in size, and easier to handle. This study compared the bond strength afforded by the plasma arc curing light with that produced by the LED curing light, according to the polymerization time. In addition, the polymerization time required for adequate adhesion of the bracket was examined. After positioning the orthodontic brackets with the composite resin onto 120 human premolars, the plasma arc curing light and the LED curing light were used to polymerize the composite resin at 4-, 6-, and 8-second timepoints. The results showed that the LED curing light produces a bond strength sufficient for maintaining the orthodontic bracket even with a short burst of polymerization. Therefore, it is expected that the LED curing light will be readily accepted by orthodontists.     

Plasma arc versus halogen light curing of orthodontic brackets: a 12-month clinical study of bond failures.

The purpose of this randomized clinical trial was to evaluate the clinical performance of brackets cured with 2 different light-curing units (conventional halogen light and plasma arc light); 83 patients treated with fixed appliances were included in the study. With the "split-mouth" design, each patient's mouth was divided into 4 quadrants. In 42 randomly selected patients, the maxillary left and mandibular right quadrants were cured with the halogen light, and the remaining quadrants were cured with the plasma arc light. In the other 41 patients, the quadrants were inverted. A total of 1434 stainless steel brackets were examined: 717 were cured with a conventional halogen light for 20 seconds; the remaining 717 were cured with the plasma arc light for 5 seconds. The number, cause, and date of bracket failures were recorded for each light-curing unit over 12 months. Statistical analysis was performed with the Fisher exact test, the Kaplan-Meier survival estimates, and the log-rank test. No statistically significant differences were found between the total bond failure rates of the brackets cured with the halogen light and those cured with the plasma arc light. Neither were significant differences found when the clinical performances of the maxillary versus mandibular arches or the anterior versus posterior segments were compared. These findings demonstrate that plasma arc lights are an advantageous alternative to conventional light curing, because they significantly reduce the curing time of orthodontic brackets without affecting the bond failure rate.     

Bond strength and clinical efficiency for two light guide sizes in orthodontic bracket bonding.

Abstract

The purpose of this study was to establish a possible increase in efficiency in bracket bonding with light-cured adhesive by using a larger size on the light transmitting unit. Two light guides were compared, a standard-sized 11-mm light guide and a 19-mm elliptical extra broad light guide, the latter designed to allow simultaneously curing of two adjacent brackets. Fifty extracted human premolars mounted in five phantom maxillary arches were bonded according to a standard procedure with Mini Uni-Twin stainless steel brackets. The two light guides were randomly chosen for each half of the maxillary arch. After bonding, all teeth were tested for tensile bond strength to failure. In the clinical study 30 patients were bonded according to a split mouth technique with the two light guides alternatively used randomly for each side of the jaw. Time for bonding and the occurrence of bracket failures were recorded. The results showed no statistically significant differences between the standard and elliptical light guides regarding tensile bond strength, or bracket failure frequency. However, with the larger light guide size a significantly shorter total bonding time for each patient was required. It is therefore concluded that the elliptical light guide in combination with a light transmitting unit of sufficient quality gave a similar bonding result as the standard light guide, offering the clinician a reduction in chair side time during the bonding procedure.     

Effects of high-speed curing devices on shear bond strength and microleakage of orthodontic brackets.

This study evaluated the shear-peel bond strength and mode of bond failure of 3 curing devices (plasma arc light, argon laser, and conventional halogen light) and 2 orthodontic bracket adhesives with different filler contents (Transbond XT and Adhesive Precoated [APC]). Observations of microleakage were also reported. Ninety human adolescent premolars were randomly divided into 6 groups, and standardized brackets were bonded according to the manufacturers' recommendations. The plasma arc light produced significantly (P =.006) higher bond strength than did the halogen light or the argon laser when Transbond was used. When APC was used, the plasma arc light and the halogen light produced similar results, and they both produced significantly (P =.015) higher bond strengths than did the argon laser. Overall, the APC showed substantially less variation in bond strength than did the Transbond. Although all curing methods showed significant microleakage (P <.001), differences among the 3 curing lights occurred only when APC was used. Microscopic evaluations demonstrated that 95% of the specimens failed for adhesion at the bracket or tooth surface; the argon laser produced the highest adhesive remnant index scores. On the basis of bond strength and microleakage results, the plasma arc light was comparable with or superior to the other curing devices, depending on the adhesive used.     

Effect of light-tip distance on the shear bond strengths of composite resin

The purpose of this study was to assess the effect of light-tip distance on the shear bond strength and failure site of brackets cured with three different light curing units: a high-intensity halogen (Astralis 10, 10-second curing), a light-emitting diode (LED, e-Light, six-second curing), and a plasma arc (PAC System, four-second curing). One hundred and thirty-five bovine permanent mandibular incisors were randomly allocated to nine groups of 15 specimens each. Stainless steel brackets were bonded with a composite resin to the teeth, and each curing light was tested at zero, three, and six mm from the bracket. After bonding, all samples were stored in distilled water at room temperature for 24 hours and subsequently tested for shear bond strength. When the three light curing units were compared at a light-tip distance of zero mm, the three lights showed no significantly different shear bond strengths. At light-tip distances of three and six mm, no significant differences were found between the halogen and plasma arc lights, but both lights showed significantly higher shear bond strengths than the LED light. When evaluating the effect of the light-tip distance on each light curing unit, the halogen light showed no significant differences between the three distances. However, the LED light produced significantly lower shear bond strengths at a greater light-tip distance, and the plasma arc lamp showed significantly higher shear bond strengths at a greater light-tip distance. In hard-to-reach areas, the use of PAC system is suggested, whereas the LED evaluated in this study is not recommended.     

Effect of curing method and curing time on the microhardness and wear of pit and fissure sealants.

OBJECTIVE: To evaluate the effects of a light source, polymerization time and storage time on the microhardness and wear of pit and fissure sealants. METHODS: Five commercial pit and fissure sealants (Fissurit F [FF], Teethmate F1 [TF], Apollo Seal [AS], Concise [CC], and Ultraseal XT Plus [US]) were used. Specimens were cured with a conventional visible light curing unit (Curing Light XL 3000) for 10, 20, 30, 40s or with a plasma arc light curing unit (Apollo 95E) for 3, 6, 9, 12s. The specimens were kept dry in light-shielded bottles at 37 degrees C for 1 week, then half of them were thermocycled. The rest of them were stored in distilled water in light-shielded bottles for another 30 days, which were kept in an incubator at 37 degrees C, followed by thermocycling. Microhardness and wear of the specimens were measured. RESULTS: Similar degree of microhardness was achieved with the shorter curing time with the plasma arc light curing unit as with the conventional visible light-curing unit. With conventional visible light curing, the microhardness of the top surface was higher than that of the bottom surface (P<0.05). With plasma arc light curing, the microhardness of the top surface was higher than that of the bottom surface for AS and CC, but for FF, TF and US, the microhardness of the top surface was lower than that of the bottom surface, except in the 3-s curing of US. For FF, AS, CC and US, wear in the 6s curing with plasma arc light was similar to or less than that of the 30s curing with conventional visible light, but for TF, wear of the 9s curing with plasma arc light was similar to that of the 20s curing with conventional visible light. After storage in distilled water for 30 days followed by thermocycling, there was a tendency towards a decrease in microhardness and an increase in wear. There was a significant negative correlation between microhardness and wear (P<0.01). SIGNIFICANCE: The tested curing methods differed significantly in their curing capacity. This study suggested that a plasma arc light curing unit needs shorter curing time than a visible light curing unit to achieve similar mechanical properties of the pit and fissure sealants tested.     

Evaluation of modifying the bonding protocol of a new acid-etch primer on the shear bond strength of orthodontic brackets

The purpose of the study was to evaluate the shear bond strength of orthodontic brackets when light curing both the self-etch primer and the adhesive in one step. Fourty eight teeth were bonded with self-etch primer Angel I (3M/ESPE, St Paul, Minn) and divided into three groups. In group I (control), 16 teeth were stored in deionized water for 24 hours before debonding. In group II, 16 teeth were debonded within half-an-hour to simulate when the initial archwires were ligated. In group III, 16 additional teeth were bonded using exactly the same procedure as in groups I and II, but the light cure used for 10 seconds after applying the acid-etch primer was eliminated, and the light cure used for 20 seconds after the precoated bracket was placed over the tooth. This saved at least two minutes of the total time of the bonding procedure. The teeth in this group were also debonded within half-an-hour from the time of initial bonding. The teeth debonded after 24 hours of water storage at 37 degrees C had a mean shear bond strength of 6.0 +/- 3.5 MPa, the group that was debonded within half-an-hour of two light exposures had a mean shear bond strength of 5.9 +/- 2.7 MPa, and the mean for the group with only one light cure exposure was 4.3 +/- 2.6 MPa. Light curing the acid-etch primer together with the adhesive after placing the orthodontic bracket did not significantly diminish the shear bond strength as compared with light curing the acid-etch primer and the adhesive separately.     

Effect of using a new cyanoacrylate adhesive on the shear bond strength of orthodontic brackets.

During bonding of orthodontic brackets to enamel, conventional adhesive systems use three different agents: an enamel conditioner, a primer solution, and an adhesive resin. A unique characteristic of some new bonding systems is that they need neither a priming agent nor a curing light to bond brackets. Such an approach should be more cost-effective for the clinician and indirectly also for the patient. The purpose of this study was to determine the effects of using a cyanoacrylate adhesive on the shear bond strength of orthodontic brackets and on the bracket/adhesive failure mode. The brackets were bonded to extracted human teeth according to one of two protocols. Group 1: Teeth were etched with 37% phosphoric acid. After applying the primer, the brackets were bonded with Transbond XT (3M Unitek, Monrovia, Calif) and were light-cured for 20 seconds. Group 2: Teeth were etched with 35% phosphoric acid. The brackets were then bonded with Smartbond (Gestenco International, G?thenburg, Sweden). The present in vitro findings indicated that the use of the cyanoacrylate adhesive to bond orthodontic brackets to the enamel surface did not result in a significantly different (P = .24) shear bond force (mean = 5.8 +/- 2.4 MPa) as compared to the control group (mean = 5.2 +/- 2.9 MPa). The comparison of the Adhesive Remnant Index scores indicated that there was significantly (P = .006) less residual adhesive remaining on the tooth with the cyanoacrylate than on the tooth with the conventional adhesive system. In conclusion, the new adhesive has the potential to be used to bond orthodontic brackets while reducing the total bonding time.     

Comparisons of two approaches for removing excess adhesive during the bonding procedure

The purpose of this study was to compare the effects on shear bond strength of removing excess adhesive from around the bracket base at 2 time periods: (1) immediately after placing the bracket on the tooth, and (2) after subjecting the adhesive to 5 seconds of light curing to initially secure the bracket in its proper position. The debonding forces were evaluated at 2 times; within half an hour after bonding and after storing for 24 hours in water at 37 degrees qC. These comparisons will help determine the most advantageous time for the clinician to remove excess adhesive from around the brackets during the bonding process. The teeth were randomly divided into 4 groups according to: (a) the time of removal of the excess adhesive from around the bracket base namely; immediately after placing the bracket or after 5 seconds of light cure and (b) the time of debonding the brackets, namely within half an hour or after 24 hours. Shear bond strength was measured using a Zwick test machine and calculated in Megapascals. The results of the analysis of variance (F = 35.05) comparing the 4 experimental groups indicated the presence of significant differences between all 4 groups (P = .0001). In general, the shear bond strengths were significantly larger for the 2 groups debonded after 24 hours, whether they were light cured for a total of 40 seconds (X = 8.8 +/- 3.6 MPa) or 45 seconds (X = 6.9 +/- 3.4 MPa). On the other hand, the shear bond strengths was significantly lower in the 2 groups debonded within half an hour from their initial bonding, whether light cured for 40 seconds (X = 0.4 +/- 1.0 MPa) or 45 seconds (X = 3.4 +/- 2.7 MPa). In conclusion, the additional 5 seconds of light cure significantly increased the initial shear bond strength. On the other hand, removing excess adhesive after 5 seconds of light cure significantly decreased the shear bond strength at 24 hours.     

The efficiency of different light sources to polymerize resin cement beneath porcelain laminate veneers

Plasma arc light units for curing resin composites have been introduced with the claim of relatively short curing times. The purpose of this study was to evaluate the efficiency of two different light sources to polymerize dual curing resin cement beneath porcelain laminate veneers. Twenty extracted healthy human maxillary centrals were used. Teeth were sectioned 2 mm below the cemento-enamel junction and crown parts were embedded into self-cure acrylic resin, labial surface facing up. Cavity preparation was carried out on labial surfaces. These teeth were divided into two groups of 10 each. The resin cement/veneer combination was exposed to two different photo polymerization units. A conventional halogen light (Hilux 350, Express Dental Products) and a plasma arc light (Power PAC, ADT) were used to polymerize resin cement. Ten specimens were polymerized conventionally (40 s) and the other specimens by plasma arc curing (PAC) (6 s). Two samples from each tooth measuring 1.2 x 1.2 x 5 mm were prepared. These sections were subjected to microshear testing and failure values were recorded. Statistically significant differences were found between the bond strength of veneers exposed to conventional light and PAC unit (P < 0.001). Samples polymerized with halogen light showed better bond strength. The results of this study suggest that the curing efficiency of PAC through ceramic was lower compared with conventional polymerization for the exposure durations tested in this study.     

Rapid curing of bonding composite with a xenon plasma arc light

The use of light-cured orthodontic adhesives is an increasingly popular method for the bonding of orthodontic brackets. However, one of the disadvantages of light-cured adhesives is their long curing times. The xenon plasma arc curing light is purported to dramatically reduce the required curing time. The purpose of this study was to test the efficiency of a xenon plasma arc light versus a conventional tungsten-quartz halogen light in producing effective bond strengths for orthodontic brackets. Standardized brackets were bonded to bovine enamel with 3 different orthodontic bonding materials. The bonding materials were exposed to the tungsten-quartz halogen light for 40 seconds and to the xenon light for 3, 6, and 9 seconds. Bond strength was tested 30 minutes and 24 hours after light-curing. The results showed that bond strength with the application of the xenon light was greater with longer exposures. There were no statistically significant differences between the bond strengths of the brackets exposed to the tungsten-quartz halogen light for 40 seconds and those exposed to the xenon light for 3, 6, or 9 seconds. However, xenon light exposures of 6 or 9 seconds were required to create bond strengths equal to those produced by the tungsten-quartz halogen light. The xenon light produced equivalent bond strengths at very short light exposures.     

Effects of using a new protective sealant on the bond strength of orthodontic brackets

This study determines the effect of applying a new protective sealant to the enamel surface on the shear bond strengths of orthodontic brackets. Sixty teeth were randomly divided into three groups. In group 1 (control), the brackets were bonded to the etched teeth using the regular sealant. In group 2, the sealant was replaced with Pro Seal and light cured as recommended by the manufacturer; the brackets were then placed, and the adhesive was light cured. In group 3, Pro Seal was applied, the bracket with the adhesive was placed on the tooth, and both Pro Seal and the adhesive were cured simultaneously. The purpose of this modification was to reduce one of the steps during the bonding procedure. A shear force was applied at the bracket-tooth interface using a Zwick Universal Test Machine. The results of the analysis of variance (F-ratio = 1.35) indicated that the shear bond strengths of the three groups were not significantly different (P = .267) from each other. The mean shear bond strength of the control group was 4.9+/-2.1 MPa. The mean shear bond strength for teeth coated with Pro Seal and light cured followed by application and light curing of the adhesive was 4.8+/-2.3 MPa, and the mean for the teeth coated with Pro Seal and then bracket placed followed by simultaneous light curing of the sealant and the adhesive was 4.0+/-1.5 MPa.     

Effects of fast halogen and plasma arc curing lights on the surface hardness of orthodontic adhesives for lingual retainers

The aims of this study were to (1) identify the optimum cure times of 2 different lingual retainer adhesives with a conventional halogen, a fast halogen, and a plasma arc light by measuring Vickers surface hardness, and (2) determine whether different lights produce similar surface hardness values for the same adhesive resin material. The investigated plasma arc curing unit was the PowerPac (American Dental Technologies, Corpus Christi, Tex), and the fast halogen unit was the Optilux 501 (Kerr, Orange, Calif). A conventional curing unit, the Ortholux XT (3M Dental Products, St. Paul, Minn) was used as the control. Two orthodontic lingual retainer adhesives were used: Transbond Lingual Retainer (3M Unitek, Monrovia, Calif) and Light Cure Retainer (Reliance Orthodontic Products, Itasca, Ill). Concise (3M Dental Products) and diluted Concise were used as controls. Transbond Lingual Retainer was polymerized by the PowerPac light in 6 seconds, by the Optilux in 10 seconds, and by the conventional halogen light in 20 seconds. The minimum curing times for Light Cure Retainer adhesive were 15 seconds for PowerPac, 10 seconds for Optilux, and 40 seconds for conventional halogen. Surface hardness values for each resin did not differ significantly with different curing units. However, different adhesives demonstrated significantly different surface hardness values. Final Vickers surface hardness values (averaged across curing units) of Transbond Lingual Retainer, Concise, diluted Concise, and Light Cure Retainer were 62.8, 52.4, 46.0, and 40.4, respectively. Plasma arc or fast halogen units polymerize resin composite adhesive in much shorter times than do conventional curing units, without a significant loss in surface hardness. Therefore, these units are suggested for clinical use to save chairside time.     

两种不同类型粘接剂和临床四手操作在正畸托槽粘结过程中的应用效果评价

目的：评价两种不同类型粘接剂和临床四手操作在正畸托槽粘结过程中的应用效果。方法：将正畸门诊40例需粘接托槽患者随机均分为四组,A组10例,四手操作粘接托槽184个,使用光固化粘接剂。B组10例,非四手操作粘接托槽180个,使用光固化粘接剂。C组10例,四手操作粘接托槽188个,使用化学固化粘接剂。D组10例,非四手操作粘接托槽192个,使用化学固化粘接剂。分别记录四组患者粘接托槽所需时间和1周以后托槽脱落情况,进行统计分析。结果：粘接单个托槽平均所需时间A组2．65min,B组3．52rain,C组1．95min,D组2．18min,A组与B组、C组与D组、A组与C、B组与D组分别有明显的统计学差异（P〈O．05）。1月后复诊四组的托槽脱落分别为5个、7个、4个、8个,托槽脱落率分别为：2．72％、3．89％、2．13％、4．16％,四组间没有明显的统计学差异（P〉0．05）。结论：在粘接托槽过程中,使用化学固化粘接剂和通过四手操作均可以明显缩短医生临床操作时间,并对粘接效果没有明显影响,工作效率显著提高。