June, 2009

Comparison of Efficacy of Fixed Appliances in the Treatment of Class I Bimaxillary Protrusion

Comparison of Efficacy of Begg, Tip-Edge and Pre-Adjusted Edgewise Appliances in the Treatment of Class I Bimaxillary Protrusion Patients Using Centroid Analysis and ICON Index

Priti S. Mulimani and Chetan V. Jayade and Vijay P. Jayade

Abstract

Objectives:

True efficiency of appliances can only be judged on the basis of systematic clinical investigation and authentic academic research. The present study was undertaken, to assess the efficiency of the three main types of fixed appliances – Begg, Pre-adjusted edgewise and Tip-edge.

Methods:

A retrospective study was conducted and pre- and post-treatment records of 10 patients in each appliance category were selected, out of a sample pool of 76 patients. Strict inclusion criteria were applied to include patients with Class I skeletal base, normodivergent growth patterns, bimaxillary dentoalveolar protrusion and treatment involving extraction of upper and lower first premolars. The assessment was done in 3 steps: 1) Evaluation of effective change in incisor and molar position using centroid analysis. 2)Cephalometric evaluation of dentoalveolar and soft-tissue changes using linear and angular measurements. 3) Application of Index of Complexity, Outcome and Need (ICON) on the pre- and post-treatment photographs and study models. The data was subjected to statistical evaluation.

Results:

There was no statistically significant difference among the three appliances. The bimaxillary dentoalveolar protrusion malocclusion was treated satisfactorily by all three appliances, to bring about favorable dental and facial changes and to achieve the desired clinical objectives.

Interpretation and conclusion:

All three appliances were equally effective in producing desired changes. Similar results can be obtained with any type of mechanotherapy, based on the skill and expertise of the operator.

Key Words: Begg, Pre-adjusted Edgwise, Tip-edge, Centroid, ICON index, Comparison

Introduction

Bringing teeth to their ideal or near-ideal positions, and making them stay in that place forever or at least for as long as possible, with the least discomfort to the patient, minimal wire-bending for the orthodontist and a maximum output for both – seems to be the holy grail of orthodontic mechanotherapy.

The multitude of appliances available for the purpose can quite simply be segregated on the basis of falling under one of the two basic philosophies – either application of light forces to move only the crowns first and correcting the roots later with a vertical slot or use of heavy forces and moving the crowns and the roots simultaneously in a horizontal slot.

The Begg appliance [1] is a prototype of the vertical slot and the Edgewise [2] appliance of the horizontal slot. A third category of appliances followed to amalgamate the benefits of both the schools of thought. The Tip-edge appliance [3] is a prototype of the third category of combination slot. Though these combination techniques have been around for quite some time, there have been no comprehensive studies in the literature which compare their efficiency with the traditional horizontal or vertical slots.

In this study, the three techniques were assessed based on their efficacy in effectively correcting Class I bimaxillary protrusion cases, which could be regarded as a common point of beginning for all three techniques. Cephalometric criteria alone for assessment of treatment changes provides only a two-dimensional, numerical picture, leaving out the vital overall changes in dental occlusion and facial aesthetics. [4] These limitations of cephalometric analysis provided the impetus for us to include the ICON index [5] in the assessment of the cases in our present study. Hence, the present study was undertaken to comprehensively evaluate the efficiency of all three techniques in the treatment of similar cases of Class I bimaxillary dentoalveolar protrusion, using cephalometric criteria, centroid analysis and ICON index.

Methodology:

A retrospective study was designed by selecting records of 10 patients treated with each appliance. In all 30 patient records were selected after applying strict inclusion criteria on a sample pool of 76 patients (Table 1). The similarity of these malocclusions was also verified statistically (Table 2).

Table 1. Average values of inclusion criteria of all ten cases in each appliance group*

No	Parameters		Inclusion Criteria to be fulfilled	BEGG		PAE		TIP-EDGE
				AVG	Range	AVG	Range	AVG	Range
1	ANB (degrees)		0 to 6	3.8	1 to 6	3.7	-1 to 6	3.7	2 to 6
2	U1 to SN (degrees)		111 to 125	117.7	112 to 124	115.9	111 to 125	115.1	112 to 119
3	U1 to NA (degrees)		27 to 40	35.4	31 to 43	32.6	27 to 40	31.8	27 to 37
4	U1 to NA (mm)		5 to 12	9.25	7 to 12	7.7	5 to 12.5	8.6	5 to 11.5
5	LI to MP (degrees)		101 to 117	109.8	106 to 117	109.9	101 to 115	108.1	101 to 114
6	LI to NB (degrees)		29 to 46	39.6	33 to 46	37.9	29 to 44	37.3	32 to 44
7	LI to NB (mm)		6.5 to 14.5	10.15	8 to 14.5	9.25	6.5 to 14	9.8	8.5 to 12
8	CROWDING	Upper	Minimal	0.35	-1 to 3	-0.65	-4 to 2	0.55	-2.5 to 3
		Lower	Minimal	1.35	-1.5 to 4	0.75	-2 to 2	2.4	0 to 4
9	SPACE FOR CORRECTING PROCLINATION (mm)	Upper	Minimal	16	12 to 22.3	12.8	10 to 16	11.8	8 to 14
		Lower	Minimal	13	4 to 18.7	10.1	5 to 13.6	10.5	8 to 16

* – Besides fulfilling the nine inclusion criteria listed in the table the cases also had to fulfill the criterion of being treated with extraction of upper and lower first premolars.

Table 2. Comparison of pre-treatment values within all three groups by statistical evaluation

		PRE-TREATMENT
		P-value	Significance
U1-SN		0.1633	NS
U1-NA	Angular	0.0407	S
	Linear	0.2232	NS
UI – N		0.7035	NS
Interincisal angle		0.0363	S
L1-MP		0.3186	NS
L1-NB	Angular	0.4866	NS
	Linear	0.5824	NS
L1-APoG	Angular	0.6810	NS
	Linear	0.5536	NS
E – Line	Upper lip	0.1760	NS
	Lower lip	0.0140	S
S – Line	Upper lip	0.1509	NS
	Lower lip	0.0107	S
H – Line		0.0417	S
Nasolabial angle		0.4965	NS
Lip Strain		0.7648	NS

S – Significant; p < 0.05

NS – Not significant; p>0.05

In the first step, a centroid analysis was done. We chose the mid-point of the tooth as our centroid to assess incisor intrusion as suggested by Hong, Hong and Koh [6] (Fig 1). The centroid was located on the pre-treatment tracing. Using this pre-treatment tracing as the template, the centroid was transferred to the post-treatment tracing for accurate measurement. The mid-point of the buccal surface of the molar crown was taken as the reference point on the lines of the method used by Moyers, van der Linden, Riolo, McNamara. [7] The mid-point of the maximum mesio-distal width was recorded as the centre of the x-coordinate. The mid-point of the minimum occluso-gingival height was marked as the centre of the y-axis. The mid-point of the entire crown was then taken as the point halfway between the two previously described mid-points. Subsequently, new x- and y-coordinates were drawn through this mid-point, which denoted the centroid of the crown. (Fig 2)

Figure 1. Determination of incisor centroid

Figure 2. Determination of molar centroid

The palatal plane and the mandibular plane were taken as reference planes for vertical measurements of maxillary and mandibular teeth respectively. A vertical reference plane, constructed perpendicular to the palatal plane at sella, was used for horizontal measurements of both upper and lower teeth, as used in the custom analysis by Mills and McCulloch, [8] The maxillary tracings were superimposed on ANS-PNS plane on ANS as recommended by McNamara [9] and the mandibular tracings were superimposed along the inferior border of mandible at the inner border of symphysis based on the guidelines outlined in the cephalometric workshop(1960). [10] The landmarks, reference planes and measurements are depicted in (Fig 3) and calculations in Table 3.

Figure 3. Landmarks and reference planes used in centroid analysis for measurement of incisor and molar movements

Table 3. Measurements and calculations used in Centroid analysis

Vertical measurements	Change represented by the measurement
(CU1 ┴ to PP) – (CU2 ┴ to PP)*	change in inciso-apical position of upper incisor
(CL1 ┴ to MP) – (CL2 ┴ to MP) *	change in inciso-apical position of lower incisor
(MU2 ┴ to PP) – (MU1┴ to PP) *	change in occluso-apical position of upper molar
(ML2 ┴ to MP) – (ML1┴ to MP) *	change in occluso-apical position of lower molar
Horizontal measurements	Change represented by the measurement
(CU1┴ toVRP) – (CU2 ┴toVRP) *	change in antero-posterior position of upper incisor
(CL1┴ toVRP) – (CL2┴ toVRP) *	change in antero-posterior position of lower incisor
(MU2┴ toVRP) – (MU1┴ toVRP) *	change in antero-posterior position of upper molar
(ML2┴ to VRP) – (ML1┴ to VRP) *	change in antero-posterior position of lower molar

* – abbreviations of landmarks listed in Table 3.

┴ -perpendicular to

Secondly, the pre- and post-treatment dentoalveolar and soft-tissue changes, using linear and angular measurements (Table 4), were compared cephalometrically. The landmarks, reference planes and measurements used are depicted in (Fig 4-6).

Table 4. Measurements used in cephalometric analysis

No.	Dentoalveolar measurements
1.	U1 – SN
2.	UI – NA
3.	UI – N ┴
4.	L1 – MP
5.	L1 – NB
6.	L1 – APoG
7.	INTERINCISAL ANGLE
	Soft-tissue measurements
8.	E – LINE Upper lip
9.	E-LINE Lower lip
10.	S – LINE Upper lip
11.	S – LINE Lower lip
12.	H – LINE
13.	NASOLABIAL ANGLE
14.	LIP STRAIN

Figure 4. Hard tissue and soft tissue landmarks used in this study

Figure 5. Cephalometric reference planes and hard tissue dentoalveolar measurements used in study

Figure 6. Soft tissue cephalometric measurements used in the study

Application of the ICON index to our samples served a dual purpose – to rate the need, pre-treatment complexity and outcome in bimaxillary dentoalveolar protrusion cases as well as to assess the applicability and validity of the index in these cases.

The ICON index was applied to the pre-treatment and post-treatment photographs and models of all 30 cases. The index had five components, all of which were scored by the recommended method (Table 5, Fig 7). The pre-treatment and post-treatment index scores were calculated (Table 6) and the treatment need, complexity, improvement and outcome for the cases were interpreted as shown in Tables 7 and 8. The results were then tabulated for all 10 patients in each group and then compared among all three groups of appliances.

Table 5. Scoring criteria for ICON index

TRAITS	SCORE	0	1	2	3	4	5
Aesthetic	1-10 As judged using IOTN AC
Upper arch crowding	Score only the highest trait either spacing or crowding	Less than 2 mm	2.1 to 5 mm	5.1 to 9 mm	9.1 to 13 mm	13.1 to 17 mm	> 17 mm or impacted teeth
Upper spacing		Up to 2 mm	2.1 -5 mm	5.1 – 9 mm	> 9 mm
Crossbite	Transverse relationship of cusp to cusp or worse	No crossbite	Crossbite present
Incisor open bite	Score only the highest trait either open bite or overbite. Lower incisor coverage	Less than 1 mm	1.1 – 2 mm	2.1 – 4 mm	> 4mm
Incisor overbite		Up to 1/3rd tooth	1/3rd to 2/3rd coverage	2/3rd up to full covered	Fully covered
Buccal segment Anteroposterior	Left and right added together	Cusp to embrasure relationship only, Class I, II or III	Any cusp relation up to but not including cusp to cusp	Cusp to cusp relationship

Figure 7. Aesthetic component of ICON index. (The Aesthetic Component was originally described as “SCAN” Evans R and Shaw WC 1987 A preliminary evaluation of an illustrated scale for rating dental attractiveness European Journal of Orthodontics 9:314-318)

Table 6. Format for recording pre- and post-treatment scores using ICON index

COMPONENTS	PRE-TREATMENT SCORE			POST-TREATMENT SCORE
	RAW	WEIGHTAGE	FINAL	RAW	WEIGHTAGE	FINAL
AESTHETIC		7			7
UPPER ARCH CROWDING / SPACING		5			5
CROSSBITE		5			5
OVERBITE /OPENBITE		4			4
BUCCAL SEGMENT A-P RELATION (LEFT + RIGHT)		3			3
TOTAL WEIGHTED SCORE
TREATMENT ?
COMPLEXITY
IMPROVEMENT
OUTCOME

Table 7. Interpretation of treatment need and complexity based on pre-treatment score

	Pre-treatment score	Interpretation
Treatment need	More than 43	Needed
	Less than 29	Easy
	29-50	Mild
	51-63	Moderate
	64-77	Difficult
	More than 77	Very difficult

Table 8. Interpretation of improvement and treatment outcome based on post-treatment score

	Post-treatment score	Interpretation
Improvement (pre-treatment score – 4 x post-treatment score)	More than -1	Greatly improved
	-25 to -1	Substantially improved
	-53 to -26	Moderately improved
	-85 to -54	Minimally improved
	Less than -85	Not improved/ Worse
Outcome	Post-treatment score of less than 31	Acceptable

Statistical tests were done to analyze any significant difference between the changes produced by the three appliances. The mean and standard deviation were calculated for pre-treatment values, post-treatment values and the difference between the two values. The data obtained was then subjected to the Student’s unpaired t–test to find out if there was any significant difference between the pre- and post-treatment values. The changes produced by all three appliances were compared by using one-way Analysis of Variance (ANOVA) test.

Level of significance was checked at five per cent. P<0.05 was considered to be significant and P>0.05 was considered to be non–significant.

Results

I. Centroid analysis:

The amount of changes produced in the upper incisor and molar regions, using centroid analysis are shown in Tables 9 and 10 respectively. The changes, when compared within all three groups, were statistically insignificant (Tables 11, 12). However, there was a statistically significant difference in lower incisor retraction between the three groups (Fig 8-9).

Table 9. Amount of incisor intrusion and retraction in all three groups assessed by centroid analysis

			Mean	SD	Paired t-test	p-value	Significance
BEGG	INTRUSION	Upper	1.1	0.91	3.84	0.0040	HS
		Lower	2.1	2.22	2.99	0.0152	S
	RETRACTION	Upper	4.0	1.73	7.30	0.0000	VHS
		Lower	2.8	1.09	8.00	0.0000	VHS
PAE	INTRUSION	Upper	1.2	1.51	2.41	0.0394	S
		Lower	2.2	1.23	5.55	0.0004	VHS
	RETRACTION	Upper	3.7	1.93	5.98	0.0002	VHS
		Lower	2.3	0.35	20.12	0.0000	VHS
TIP- EDGE	INTRUSION	Upper	1.2	1.04	3.71	0.0048	HS
		Lower	2.7	2.24	3.75	0.0046	HS
	RETRACTION	Upper	3	2.23	4.18	0.0024	HS
		Lower	1.8	0.82	6.65	0.0001	VHS

NS-not statistically significant p>0.05; S-statistically significant at p<0.05; HS-highly significant at p<0.01; VHS-very highly significant at p<0.001

Table 10. Amount of molar extrusion and protraction in all three groups assessed by centroid analysis

			Mean	SD	Paired t-test	p-value	Significance
BEGG	EXTRUSION	Upper	-0.56	1.66	-1.05	0.3214	NS
		Lower	-1.9	1.94	-3.01	0.0147	S
	PROTRACTION	Upper	3.6	3.16	3.60	0.0057	HS
		Lower	2.7	1.49	5.71	0.0003	VHS
PAE	EXTRUSION	Upper	-1.7	1.63	-3.19	0.0109	S
		Lower	-1	1.67	-1.79	0.1063	NS
	PROTRACTION	Upper	3.6	2.03	5.62	0.0003	VHS
		Lower	3.5	1.04	10.24	0.0000	VHS
TIP- EDGE	EXTRUSION	Upper	-0.5	1.28	-1.11	0.2947	NS
		Lower	-1.4	1.16	-3.69	0.0050	HS
	PROTRACTION	Upper	2.5	2.15	3.72	0.0048	HS
		Lower	2.8	1.07	8.20	0.0000	VHS

NS-not statistically significant p>0.05; S-statistically significant at p<0.05; HS-highly significant at p<0.01; VHS-very highly significant at p<0.001

Table 11. Comparison of incisor intrusion and retraction in all three groups by ANOVA test

		Mean	SD	P-value	Significance
INTRUSION	Upper	1.16	1.14	0.9721	NS
	Lower	2.3	1.9	0.7863	NS
RETRACTION	Upper	3.5	1.95	0.4897	NS
	Lower	2.3	0.89	0.0351	S

NS-not statistically significant p>0.05; S-statistically significant at p<0.05

		Mean	SD	P-value	Significance
INTRUSION	Upper	-0.9	1.58	0.1712	NS
	Lower	-1.4	1.61	0.4728	NS
RETRACTION	Upper	3.2	2.46	0.5463	NS
	Lower	3.0	1.23	0.3091	NS

NS-not statistically significant p>0.05.

Figure 8. Comparison of incisor intrusion and retraction with the three appliances using centroid analysis

Figure 9. Comparison of molar extrusion and protraction with the three appliances using centroid analysis

On finding that there was significant amount of upper molar extrusion with the PAE appliance and significant amount of lower molar extrusion in the Begg and Tip-edge groups, an additional component was added to the study to assess the effect of these changes on the mandibular plane angle(FMPA) and the lower anterior face height (LAFH) (measured from ANS to menton). Pre- and post-treatment changes in the LAFH and FMPA values were assessed. The results showed that, the difference between the three groups remained statistically insignificant (Tables 13, 14).

Table 13. Changes in the mandibular plane angle and lower anterior face height in all three appliances

		Mean	SD	Paired t-test	p-value	Significance
BEGG	FMPA	2	2.45	2.58	0.0296	S
	LAFH	2.1	2.0	3.37	0.0082	HS
PAE	FMPA	0.9	2.33	1.22	0.2531	NS
	LAFH	0.4	1.78	0.71	0.4945	NS
TIP- EDGE	FMPA	0.9	2.23	1.27	0.2345	NS
	LAFH	1.3	2.06	2.0	0.0768	NS

NS-not statistically significant p>0.05; S-statistically significant at p<0.05; HS-highly significant at p<0.01

Table 14. Comparison of changes in the mandibular plane angle and lower anterior face height in all three groups by ANOVA test

	Mean	SD	P-value	Significance
FMPA	1.3	2.3	0.4880	NS
LAFH	1.3	2.0	0.1652	NS

NS-not statistically significant p>0.05

II. Cephalometric evaluation of dentoalveolar and soft-tissue changes:

Overall, there was no statistically significant difference in the efficacy of the appliances under study in treating the condition of bimaxillary dentoalveolar protrusion (Tables 15, 16; Fig 10, 11, 12).

Table 15. Comparison of treatment change produced by the three groups by ANOVA test (hard-tissue)

		P-value	Significance
U1-SN		0.6826	NS
U1-NA	Angular	0.4639	NS
	Linear	0.2446	NS
UI – N ┴		0.4676	NS
Interincisal angle		0.3593	NS
L1-MP		0.3727	NS
L1-NB	Angular	0.6875	NS
	Linear	0.3769	NS
L1-APoG	Angular	0.2318	NS
	Linear	0.1704	NS

NS-not statistically significant p>0.05

Table 16. Comparison of treatment change produced by the three groups by ANOVA test (soft-tissue). Marked effects are significant at p < .05000

		P-value	Significance
E – Line	Upper lip	0.6930	NS
	Lower lip	0.3774	NS
S – Line	Upper lip	0.4783	NS
	Lower lip	0.3888	NS
H – Line		0.1379	NS
Nasolabial angle		0.5716	NS
Lip Strain		0.6621	NS

NS-not statistically significant p>0.05

Figure 10. Comparison of changes in the cephalometric values for upper incisor position with the three appliances

Figure 11. Comparison of changes in the cephalometric values for lower incisor position with the three appliances

Figure 12. Comparison of changes in the cephalometric values for soft tissue with the three appliances

III. Assessment using icon index

a. Assessment of treatment need:

As judged by the ICON index, 57 per cent of the total 30 cases needed treatment whereas 43 per cent of the cases did not need any treatment (Fig 13).

Figure 13. Treatment need assessed by ICON index

b. Assessment of treatment complexity:

Maximum number of cases i.e., 53 per cent fell under the mild category, whereas 37% were assessed to be moderately complex, 7 per cent easy, 3 per cent difficult and none of the cases very difficult (Fig 14).

Figure 14. Treatment complexity assessed by ICON index

c. Assessment of improvement:

Most of the cases –56 per cent – were found to show minimal improvement by the index. Moderate improvement was seen in 27 per cent, substantial improvement in 10 per cent and no improvement in 7 per cent of the cases. None of the cases showed great improvement. (Fig 15)

Figure 15. Treatment complexity assessed by ICON index

d. Assessment of treatment outcome:

The treatment outcome was acceptable in 83 per cent of the cases and not acceptable in 17 per cent of the cases (Fig 16).

Figure 16. Assessment of treatment outcome using ICON index

Discussion

In the present retrospective study, using any of the three appliances for correction of bimaxillary dentoalveolar protrusion following first premolar extractions, resulted in significant amount of upper and lower anterior retraction and achievement of a pleasing facial appearance and profile and there was no statistically significant differences between the three.

Studies comparing techniques like standard edgewise, Tweed’s and Begg’s abounded when they were newly introduced. In recent times, other than comparison between the various prescription-types of the PAE, there have been very few studies comparing older appliances like refined Begg technique with newer ones like PAE and Tip-edge. Hence, in this section, we could not directly compare our study with any such study. Comparisons were made mostly with results obtained with standard edgewise and classical Begg techniques.

A. Centroid analysis:

1. Upper incisor intrusion: In our study, all three appliances produced similar amounts of upper incisor intrusion of 1.2 mm, which was in concurrence with the finding by Barton(1973) [11] who reported no significant difference between the Begg and edgewise appliances in his study.

2. Upper incisor retraction: Maximum upper incisor retraction was obtained with the Begg appliance –4 mm – next with the PAE appliance –3.7 mm– and then with the Tip-edge appliance –3 mm. This contradicted Venezia’s [12] study wherein maxillary incisor retraction of 2.8 mm was obtained with the Begg appliance and 5 mm with the edgewise appliance. Barton’s [11] study showed that though both the Begg and PAE appliances retracted the maxillary incisors to a great extent, the edgewise appliance had better torquing action. McKinney and Harris [13] and Fischer and Ricketts [11] also reported under-torqued and upright maxillary incisors with the Begg technique.

   In contrast, the maxillary incisors were adequately torqued in our study by the Begg technique due to the refinements in Begg biomechanics incorporated during treatment. Controlled tipping using light auxiliaries was initiated right from the space closure stage itself, which made third stage of treatment more efficient and effective.

3. Lower incisor intrusion: The PAE appliance showed very highly significant lower incisor intrusion of 2.2 mm(S.D.–1.23), followed by 2.7 mm(S.D.–2.24) by the Tip-edge appliance and 2.1 mm(S.D.– 2.22) by the Begg appliance. However, Barton [11] and Venezia [12] reported that the Begg appliance intruded lower incisors more than the edgewise appliance.

4. Lower incisor retraction: This was the only parameter showing statistically significant difference between the three appliances, which was due to the significant amount of lower incisor retraction of 2.8 mm(S.D.–1.09) by the Begg appliance as compared to 1.8 mm by the Tip-edge appliance. This figure of 2.8 mm for the Begg appliance was comparable to the figure of 2.7 mm, obtained by Barton [11] in his study.

5. Upper molar extrusion: Upper molars extruded significantly in the PAE appliance by 1.7 mm. Minimal upper molar extrusion occurred with Begg (0.57) and Tip-edge (0.5) techniques. However, the difference between the three appliances was not statistically significant.

6. Upper molar protraction: The upper molars were protracted to the least extent by the Tip-edge appliance –2.5 mm– and to a similar extent by PAE and Begg technique –3.6 mm. This finding contradicted the observation by Barton [11] and Venezia [12], that there was more maxillary molar anchorage loss with the Begg appliance than with the edgewise technique.

7. Lower molar extrusion: Statistically significant amount of lower molar extrusion occurred with the Begg – 1.9 mm- and Tip-edge –1.4 mm– techniques. This was expected, due to the use of Cl II elastics in both the techniques. The finding was in agreement with the studies by Ricketts and Fischer [11] and Venezia [12].12 The molar extrusion of 2mm in our study was less than the value of 2.6mm quoted by Miestrell et al and Riolo and associates [14] and of 2.8 mm by Menezes. [15]

8. Lower molar protraction: The PAE appliance exhibited maximum lower molar protraction of 3.5 mm and the Begg appliance the least, of 2.7 mm. Similar finding was reported by McKinney and Harris. [13]

Vertical changes:

1. FMPA: Opening of the mandibular plane angle was found to occur to a slightly greater extent in both Barton [11] and Venezia [12] study, when compared to the edgewise appliance, similar to the finding in our study. Mandibular plane opened by 1.26^o in Meistrell’s [14] study as against 2^o in our study.

2. LAFH: Increase in lower anterior face height with the Begg technique was also reported by Menezes [15] and Carter, [16] which was attributed to lower molar extrusion.

Consequently, Class II elastics have to be used with caution in high-angle cases to avoid unfavorable clinical repercussions.

B. Cephalometric assessment of soft-tissue changes:

In the present study, there was found to be no statistically significant difference between the three appliances in bringing about soft-tissue changes, which was concurrent to the findings by Drobocky and Smith(1989) [17] who evaluated the changes in profiles produced by different appliances like standard edgewise, PAE and Begg after first premolar extraction.

C. ICON index:

a. Assessment of Treatment Need:

In the present study, we discovered that the utility of ICON index, in assessing treatment need when applied to Cl I bimaxillary protrusion cases was quite inadequate. The large percentage of patients not requiring treatment, as indicated by the index, was due to the basic incompatibility between the nature of the bimaxillary dentoalveolar protrusive malocclusion and the method of assessment of treatment need by the ICON index. Patients with this particular malocclusion exhibited very well-aligned upper and lower anteriors, though they were severely proclined, an excellent Class I buccal segment occlusion and edge-to-edge/minimal overbite. As a result the pre-treatment score rarely exceeded 4 on the scale of dental attractiveness when cases were compared with the pictures of the Aesthetic Component, which had the highest weightage in the index (Fig 7). This poorly reflected the treatment need even in severe cases.

Dawjee, Ackerman and Shaw [18] had proposed changes to extend the applicability of this index to bimaxillary protrusion cases.

b. Assessment of Treatment Complexity:

Our study indicated that the pre-treatment ICON scores did not accurately reflect the complexities and difficulties encountered in the treatment of critical anchorage bimaxillary protrusion cases. This concurred with the study by Richmond et al [19,20] in which it was found that the pre-treatment ICON score was not a good predictor of treatment difficulty.

c. Assessment of Treatment Outcome:

The ICON index required a more stringent standard to attain a treatment outcome of ‘greatly improved’ category than other indices, [21] which was proved in our study where not a single case out of 30 fell into the greatly improved category and only 3 fell in the substantially improved category. This could be due to the low pre-treatment scores as discussed previously.

To summarise, all three appliances under study were equally effective in correcting Class I bimaxillary dentoalveolar protrusion and there was no significant difference between the three when statistically evaluated.

In any given clinical situation, any type of appliance can be used, based on appropriate diagnosis and case selection. As is of often said, the appliance is as good as the operator.

The study had drawbacks of being a retrospective one, having a small sample size and being treated by students undergoing training for the post-graduate course. Although the inexperienced operators were supervised at every step by accomplished and experienced members of the staff, operator efficiency did come into the picture.

For future studies, a prospective study can be designed with a large sample size and subjects standardized for age, gender and anchorage management protocol.

Conclusion:

1. The Begg, Pre-adjusted edgewise and Tip-edge appliances were equally effective in treating bimaxillary protrusion to satisfactory end results. Hence, any of the three appliances can be used effectively, with appropriate case selection and management, to produce similar outcomes.
2. The modern Begg appliance, with several refinements it incorporates, can match newer and more recent appliances, in terms of both, treatment changes produced and treatment objectives achieved.
3. Since the Begg and Tip-edge appliances also brought about slight increase in the mandibular plane angle and lower anterior face height, they have to be used with caution in high angle cases with judicious management of Class II elastic usage.
4. The pre-adjusted edgewise appliance with built-in prescriptions, produced changes in values, closely matching the Begg appliance. In critical anchorage cases, anchorage reinforcement methods for the lower molar might be required, since lower molar anchorage loss was evident.
5. The ICON index was not very effective in assessing treatment need and complexity in bimaxillary protrusion cases.

References

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Contributed by:

Co-Author

Dr. Priti Mulimani
Assistant Professor, P.M.N.M Dental College, Bagalkot, Karnataka, India

Dr. Chetan V. Jayade
Associate Professor, Sibar Institute of Dental Sciences, Guntur, Andhra Pradesh, India

Dr. Vijay P. Jayade
Professor Emiretus, Sibar Institute of Dental Sciences, Guntur, Andhra Pradesh, India