- Dentofacial Orthopedic Appliances - Functional Appliances - Twin Block - Bracket's Prescription Selection after Dentofacial Orthopedic Appliances

1. Nasir Al-Hamlan, BDS, FDS RCSEd MPH, MSc, MOrth RCSEd, FICD
Consultant, Orthodontic Section
King AbdulAziz Dental Center
NGHA, Riyadh
DENTOFACIAL ORTHOPEDIC APPLIANCE
TWIN BLOCK
@nhalhamlan
@saudibraces
nasiralhamlan
@nasiralhamlan

2. SOURCE OF INFORMATION!
COLLEAGUES
EVIDENCE BASE
EXPERIENCES

3. SOURCE OF INFORMATION!
TRIALS (SUCCESS AND FAILURES)
BASIC AND DEBATABLE EVIDENCE
COLLECTING

4. •STRAIGHT TEETH LOOK SO MUCH NICER THAN CROOKED ONES! PEOPLE WHO
DISLIKE (OR EVEN HATE) THEIR TEETH DON’T TEND TO SMILE.
•CROOKED TEETH ARE VERY COMMONLY ASSOCIATED WITH MALOCCLUSIONS.
•MALOCCLUSION CAN LEAD TO:
- EXCESSIVE WEAR ON THE TEETH;
- DAMAGE TO THE SOFT TISSUES;
- MALOCCLUSIONS CAN BE ONE FACTOR IN TMD;
- DIFFICULTY IN CHEWING;
- CROOKED TEETH ARE HARDER TO KEEP CLEAN THAN STRAIGHT TEETH.
WHY SHOULD WE STRAIGHTEN THE TEETH?

5. 1. AESTHETIC 85% - 90%
2. FUNCTIONAL (DISPLACEMENT) 10-15%
- DISORDER OF MASTICATION
- DISPLACEMENT
3. HEALTH 5%
- PSYCHOLOGICAL HEALTH
- TMD
- TRAUMATIC OB
- TRAUMATIC OJ
- STRAIGHT TEETH + CLEANING
INDICATIONS OF ORTHODONTIC TREATMENT

6. THE DENTAL SPECIALTY THAT INCLUDES THE DIAGNOSIS, PREVENTION,
INTERCEPTION, AND CORRECTION OF MALOCCLUSION, AS WELL AS
NEUROMUSCULAR AND SKELETAL ABNORMALITIES OF THE DEVELOPING OR
MATURE OROFACIAL STRUCTURES (ADA ORGANISATION).
ORTHODONTICS AND DENTOFACIAL ORTHOPEDICS:

7. ORTHODONTICS AND DENTOFACIAL ORTHOPEDICS
•ORTHO: MEANS “STRAIGHT” OR “CORRECT.”
•DONTIC: PORTION OF THE WORD MEANS “PERTAINING TO TEETH.”
ORTHODONTICS
DENTOFACIAL
•DENTO: MEANS “TEETH”
•FACIAL: MEANS “FACE”
•ORTHO: MEANS “STRAIGHT"
•PEDIC: MEANS “BONES”
ORTHOPEDICS

8. DENTOFACIAL ORTHOPEDICS IS THE PROCESS OF NORMALIZING THE
GROWTH OF A PATIENT’S BONE STRUCTURE AND REPAIRING ANY
IMBALANCES OF THE FACE AND JAWS.
•IN CHILDREN: INVOLVES THE GUIDANCE OF FACIAL GROWTH AND
FACIAL DEVELOPMENT, CONTROLLING BONE GROWTH AND TOOTH
MOVEMENT.
•IN ADULTS: INVOLVES SURGERY

9. •GROWTH MODIFICATION INVOLVING FUNCTIONAL APPLIANCES HAVE THE
OBJECTIVES OF ACTING AS A THERAPEUTIC BIOMECHANICAL INTERFERENCE
TO CAUSE CLINICALLY SIGNIFICANT MORPHOLOGICAL ALTERATIONS IN A
GROWING CHILD’S DENTITION AND CRANIOFACIAL SKELETON (VIG AND VIG,
1986)
GROWTH MODIFICATION

10. FUNCTIONAL APPLIANCES
DEFINITION:
• REMOVAL OR FIXED ORTHODONTIC APPLIANCES WHICH USE FORCES GENERATED BY THE
STRETCHING OF MUSCLES, FACIA, AND OR PERIODONTIUM TO AFTER SKELETAL AND
DENTAL RELATIONSHIPS.
• THEY ARE ALSO KNOWN AS DENTOFACIAL ORTHOPEDIC APPLIANCES
•AIM:
- CORRECTION OF OVERJET AND OVERBITE,
- CORRECTION OF MOLAR RELATIONSHIP,
- CORRECTION OF TRANSVERSE RELATIONSHIP,
- ALTER SOFT TISSUES ENVIRONMENT

11. WHAT IS THE FIRST DENTOFACIAL ORTHOPEDIC APPLIANCE USED BY CHILD?
QUESTION

12. WHAT IS THE FIRST DENTOFACIAL ORTHOPEDICS IS
USED BY CHILD?

13. QUESTION
WHAT IS THE FIRST DENTOFACIAL ORTHOPEDICS IS USED BY CHILD?
- PLACES BENEFICIAL ORTHOPEDIC FORCES ON THE JAWS;
- PROMOTE POSITIVE DOWN AND FORWARD GROWING FORCES REQUIRED BY BOTH UPPER
AND LOWER JAWS;
- SUCKLING FORCES GENERALLY ACT TO FORM WIDE DENTAL ARCHES;
- HELPS TO DEVELOP AIRWAYS (PACIFIER SUCKLING DEFORMS AIRWAYS);
- SUCKLING ALSO PROMOTES GOOD SWALLOW MUSCLE TONE WHICH ASSISTS PROPER JAW
AND AIRWAY DEVELOPMENT.
BREASTFEEDING

14. WHY SHOULD WE USE DENTOFACIAL ORTHOPEDICS APPLIANCES?

15. •MOST EFFECTIVE SKELETAL CLASS II TREATMENT (RETROGNATHIA),
•REPOSITION THE MANDIBLE,
•MUSCLE STRETCHING,
•FORCES TRANSMITTED TO DENTITION AND BASAL BONE,
•RESULTING IN ORTHODONTIC AND ORTHOPEDIC CHANGES (BISHARA, 1989),
•MOST COMMON: CORRECTION OF LARGE OJ CAUSED BY RETROGNATHIC MANDIBLE,
•IT HELPS TO AVOID SURGICAL CORRECTION AT A LATER STAGE OF DEVELOPMENT.
•THE BENEFITS OF COMBINED DENTAL ORTHOPEDIC AND ORTHODONTIC THERAPY ARE NOT
TEMPORARY BUT PERMANENT?!
WHY SHOULD WE USE DENTOFACIAL ORTHOPEDICS APPLIANCES?

16. - IMPROVE AESTHETICS
- DECREASED TRAUMA RISK TO ANTERIOR TEETH
- EARLY CORRECTION OF DELETERIOUS HABIT
- IMPROVE EVENTUAL PROGNOSIS
- DECREASE LENGTH OF DEFINITIVE TREATMENT
(TWELFTREE, 1998)
WHY SHOULD WE USE DENTOFACIAL ORTHOPEDICS APPLIANCES?

17. WHEN SHOULD WE USE DENTOFACIAL ORTHOPEDICS APPLIANCES?

18. - DURING ACTIVE GROWTH,
- MOST COMMON TIME FOR TREATMENT IS DURING PUBERTAL GROWTH SPURT,
WHEN SHOULD WE USE DENTOFACIAL ORTHOPEDICS APPLIANCES?
•THE FASTER GROWTH, THE FASTER THE
RESPONSE, THE SHORTER THE TREATMENT TIME,

19. WHAT MALOCCLUSIONS CAN WE TREAT WITH DENTOFACIAL
ORTHOPEDIC APPLIANCES?
• CLASS II DIVISION 1
- HIGH ANGLE?
• CLASS II DIVISION 2
- LOW ANGLE
• CLASS III

20. • CLASS II DIV 1
- IDEAL CASE
WHAT MALOCCLUSIONS CAN WE TREAT WITH DENTOFACIAL ORTHOPEDIC APPLIANCES?

21. WHAT MALOCCLUSIONS CAN WE TREAT WITH DENTOFACIAL ORTHOPEDIC APPLIANCES?
• CLASS II DIV 2
?

22. WHAT MALOCCLUSIONS CAN WE TREAT WITH DENTOFACIAL ORTHOPEDIC APPLIANCES?
• CLASS III
?

23. INDICATIONS
• CLASSIC CASE
- PROCLINED UPPER INCISORS, UNCROWDED, WELL ALIGNED CLASS II.1 ON MILD/ MODERATE
SKELETAL II BASE WITH NO SUBSEQUENT NEED FOR FIXED APPLIANCES,
DENTOFACIAL ORTHOPEDIC APPLIANCES
• COMMONLY USED
- MODERATE/SEVERE SKELETAL II WITH NORMAL-LOW MMPA.

24. CONTRAINDICATIONS
DENTOFACIAL ORTHOPEDIC APPLIANCES
•ADULT
•HIGH ANGLE
•PROCLINED LOWER INCISORS
•AOB
MAY BE!

25. - MANDIBULAR INCISOR PROCLINATION,
- AN INCREASE IN THE VERTICAL FACIAL DIMENSION IS SEEN,
- CLOCKWISE ROTATION OF THE MAXILLARY PLANE,
- LIMITED INCREASE IN MANDIBULAR GROWTH,
- RELAPSE
DISADVANTAGES
DENTOFACIAL ORTHOPEDIC APPLIANCES

26. •GOOD BUCCAL INTERDIGITATION REDUCE DENTALRELAPSE
DENTOFACIAL ORTHOPEDIC APPLIANCES
STABILITY
• PANCHERZ AND FACKEL, 1990
- 58% DENTAL RELAPSE
- 42% SK RELAPSE

27. • BORNE BASED CLASSIFICATION
• MALOCCLUSION
• MODE OF ACTION
CLASSIFICATION OF DENTOFACIAL ORTHOPEDIC APPLIANCES

28. •BORNE BASED CLASSIFICATION
‣ TISSUE BORNE‣ TOOTH BORNE
CLASSIFICATION OF DENTOFACIAL ORTHOPEDIC APPLIANCES

29. ‣ CLASS III APPLIANCES‣ CLASS II APPLIANCES
•MALOCCLUSION
- TWIN BLOCKS
- MOA
- FR II
- HERBST
- TWIN BLOCKS
- FR III
CLASSIFICATION OF DENTOFACIAL ORTHOPEDIC APPLIANCES

30. •MODE OF ACTION
‣ MYOTONIC: LARGE MANDIBULAR
OPENING (8-10MM), WORK BY
PASSIVE MUSCLE STRETCH,
- HARVOLD
‣ M Y O D Y N A M I C : M E D I U M
MANDIBULAR OPENING (<5MM),
WORK BY STIMULATING MUSCLE
ACTIVITY,
- TWIN BLOCK
- MOA
- FR II
- HERBST
CLASSIFICATION OF DENTOFACIAL ORTHOPEDIC APPLIANCES

31. ORTHODONTIC FORCE ORTHOPEDIC FORCE

32. ORTHODONTIC FORCE
- THE OPTIMUM ORTHODONTIC FORCE AS 28G PER SQUARE
CENTIMETRE OF ROOT SURFACE (SCHWARZ, 1932);
- OPTIMUM FORCE LEVELS IN THE EDGEWISE APPLIANCE,
FOUND THAT 150 G WAS THE OPTIMUM FORCE FOR MOVING
CANINES, COMPARED TO 300 G FOR MOLARS (SMITH AND
STOREY, 1952);
- APPLYING LIGHT FORCES WITH ARCHWIRES AND ELASTIC
TRACTION, FIXED APPLIANCES DO NOT SPECIFICALLY
STIMULATE MANDIBULAR GROWTH DURING TREATMENT;
- THRESHOLD: 6 HOURS PER DAY.

33. ORTHODONTIC FORCE ORTHOPEDIC FORCE

34. ORTHOPEDIC FORCE
- ORTHOPEDIC FORCE LEVELS ARE NOT CONFINED BY THE LEVEL OF TOLERANCE OF THE
PERIODONTAL MEMBRANE,
- IN CLASS II SKELETAL RELATIONSHIP, 1 MM OF ANTERIOR DISPLACEMENT THE FORCES OF THE
STRETCHED RETRACTOR MUSCLES AMOUNT TO APPROXIMATELY 100 G (GRAF; 1961, 1975) (WITT
AND KOMPOSCH, 1971).
- 14 HOURS PER DAY

35. MODE OF ACTION OF DENTOFACIAL
ORTHOPEDIC APPLIANCES

36. DENTOALVEOLAR EFFECTS ( 60-70%)
• DENTO-ALVEOLAR CHANGES:
- TIPS TEETH, 70% OJ REDUCTION DUE TO TIPPING IN CLASS II CASES
•INCISOR ANGULATION:
- UPPER INCISORS RETROCLINE: 14° (RETROCLINE 9° EVEN WITHOUT WIRE WORK)
- INCISORS LOWER INCISORS PROCLINE: 8°±7° (LUND AND SANDLER, 1998), 4.6° ±4°
(1.7MM) (HARRADINE & GALE, 2000) - HAD LOWER INCISOR CAPPING.
- INCORPORATING A SOUTHEND CLASP LIMITS THIS PROCLINATION (TRENOUTH AND
DESMOND, 2012)
• INHIBITION OF DOWNWARD AND FORWARD ERUPTION OF MAXILLARY TEETH.
• MESIAL ERUPTION OF LOWER POSTERIOR TEETH.
MODE OF ACTION OF DENTOFACIAL ORTHOPEDIC APPLIANCES

37. DENTOALVEOLAR EFFECTS
MODE OF ACTION OF DENTOFACIAL ORTHOPEDIC APPLIANCES

38. ORTHOPEDIC (SKELETAL) EFFECTS ( 30-40%)
• CONDYLAR GROWTH
- INCREASED CONDYLAR REMODELLING (REDIRECTION OF CONDYLAR GROWTH FROM
UPWARD AND FORWARD DIRECTED GROWTH TO POSTERIOR DIRECTION)
- INCREASED GLENOID FOSSA REMODELLING (ADAPTIVE CHANGES TO GLENOID FOSSA
LOCATION TO A MORE ANTERIOR AND VERTICAL DIRECTION)
• RESTRICTION OF FORWARD GROWTH OF MAXILLA
• STIMULATION OF MANDIBULAR GROWTH BEYOND WHAT IS NORMALLY SEEN IN GROWING
CHILDREN
• INCREASED LOWER FACIAL HEIGHT
• CHANGES IN NEUROMUSCULAR ANATOMY AND FUNCTION THAT WOULD INDUCE BONE
REMODELLING
MODE OF ACTION OF DENTOFACIAL ORTHOPEDIC APPLIANCES

39. MODE OF ACTION OF DENTOFACIAL ORTHOPEDIC APPLIANCES
ORTHOPEDIC (SKELETAL) EFFECTS

40. AMOUNT OF GROWTH

41. AMOUNT OF GROWTH
MAXILLA
- RESTRAINT; 0.9° REDUCTION SNA (WIESLANDER, 1993; MILLS AND MCCULLOCH, 1998)
- RESTRAINT MAY INCREASE AFTER END OF TREATMENT (PANCHERZ & ANEHUS- PANCHERZ, 1993)
- NO RESTRAINT (KEELING ET.AL., 1998)

42. AMOUNT OF GROWTH

43. AMOUNT OF GROWTH
• MANDIBLE
- METHOD OF MEASUREMENT IMPORTANT AND CARE NEEDED WHEN LOOKING AT RESULTS;
IF CO-GN USED: INCREASE MANDIBLE LENGTH WILL BE > THAN A-P MEASUREMENT IN
DEGREES,
- ENHANCEMENT OF TOTAL MANDIBULAR LENGTH: 4.2MM COMPARED TO CONTROL, BUT
POINT B MOVED 2.1MM MORE ANTERIORLY, SNB ENHANCED BY 1.6° (MILLS AND
MCCULLOCH, 1998),
- INCREASE GROWTH RATE: INCREASE 1.5MM/YR MORE GROWTH IN 9-10YR OLDS,
INCREASE 1MM/YR MORE GROWTH IN 10-12YR OLDS (MARSCHNER AND HARRIS, 1966)

44. - A LACK OF GROWTH RESPONSE MAY BE RELATED TO THE LEVEL OF
ENDOCRINE ACTIVITY;
- IF THE TREATMENT OCCURS DURING A RESTING PHASE OF GROWTH.
SOME EXPLANATIONS WHEN THERE IS NO CHANGE WITH
DENTOFACIAL ORTHOPEDIC APPLIANCES!

45. HOW TO PREDICT GROWTH?

46. HOW TO PREDICT GROWTH?
DENTOFACIAL ORTHOPEDICS APPLIANCES ARE MORE EFFECTIVE IF THEIR USE IS TIMED TO
COINCIDE WITH THE ADOLESCENT GROWTH SPURT, OR MORE SPECIFICALLY PEAK HEIGHT
VELOCITY (PHV) AS THE PEAK IN ADOLESCENT MAXILLARY AND MANDIBULAR GROWTH OCCURS
AT THE SAME TIME OR JUST AFTER PHV (BACCETTI ET AL, 2000).
• CHRONOLOGICAL AGE:
- AROUND 12 YEARS OF AGE IN GIRLS AND 14 IN BOYS, HOWEVER, IS A POOR PREDICTOR,
- HAND-WRIST: THE PREDICTIVE VALUE OF HAND–WRIST RADIOGRAPHS APPEARS TO IMPROVE CLOSER TO THE PHV,
BUT THEY NEED TO BE OBTAINED AT REGULAR INTERVALS AND EXPERIENCE (HOUSTON, 1979). AS SUCH, THEY ARE
RARELY USED.
• CERVICAL VERTEBRAE: THEIR DEVELOPMENT HAS BEEN STAGED AND SHOWS GOOD CORRELATION WITH SKELETAL
MATURITY. MOST IMPORTANT ARE C2, C3 AND C4.
•GROWING PREDICTION

47. HOW TO PREDICT GROWTH?
•GROWING PREDICTION
•IN SUMMARY
EARLY TREATMENT: 9-10 YRS
DEFINITIVE TREATMENT: 12-13YRS
GROWING PATIENT (10-12 YRS GIRLS AND 12-14 YRS BOYS)

48. HOW LONG DENTOFACIAL ORTHOPEDIC
APPLIANCES SHOULD BE WORN PER DAY?

49. HOW LONG DENTOFACIAL ORTHOPEDIC
APPLIANCES SHOULD BE WORN PER DAY?
•12-14 HRS - E.G. ANDRESEN, HARVOLD, BIONATOR
•FULL-TIME - E.G. TB, FRANKEL (EXCEPT FOR EATING/SPORTS)

50. WHICH BRACKET PRESCRIPTION FOR THE
SECOND PHASE (AFTER DENTOFACIAL
ORTHOPEDIC TREATMENT)?

51. WHICH BRACKET PRESCRIPTION FOR THE SECOND PHASE (AFTER DENTOFACIAL
ORTHOPEDIC TREATMENT?
POST DENTOFACIAL ORTHOPEDICS PHASE
POST FIXED ORTHODONTIC PHASE
TORQUE

52. WHICH BRACKET PRESCRIPTION FOR THE SECOND PHASE (AFTER DENTOFACIAL
ORTHOPEDIC TREATMENT?
ANGULATION

53. WHICH BRACKET PRESCRIPTION FOR THE SECOND PHASE (AFTER DENTOFACIAL
ORTHOPEDIC TREATMENT?
ANGULATION

54. WHICH BRACKET PRESCRIPTION FOR THE SECOND PHASE (AFTER DENTOFACIAL
ORTHOPEDIC TREATMENT?
CONVENTIONAL BRACKETS

55. WHICH BRACKET PRESCRIPTION FOR THE SECOND PHASE (AFTER DENTOFACIAL
ORTHOPEDIC TREATMENT?
SELF-LIGATING BRACKETS
HIGH TORQUE
UPPER CENTRAL +22 DEGREE
LOW TORQUE
LOWER -11 DEGREE

56. TWIN BLOCK
THE MOST POPULAR DENTOFACIAL ORTHOPEDIC APPLIANCES WORLDWIDE

57. WILLIAM J. CLARK

58. A YOUNG PATIENT COLIN GOVE, SON OF A DENTIST FELL AND
COMPLETELY LUXATED AN UPPER CENTRAL INCISOR. FORTUNATELY, HE KEPT
THE TOOTH AND WITHIN FEW HOURS OF THE ACCIDENT THE TOOTH WAS
REIMPLANTED USING TEMPORARY SPLINT AND LATER ON WITH STABILIZING
SPLINT.
AFTER 6 MONTHS, THE OCCLUSAL RELATION WAS CL-II DIV 1 WITH
OVERJET OF 9MM AND LIP TRAP. THIS LIP TRAP WAS CAUSING MOBILITY
AND ROOT RESORPTION.
HISTORY

59. HISTORY
THEN IT WAS NECESSARY TO DESIGN AN APPLIANCE THAT COULD BE
WORN FULL TIME TO POSTURE THE MANDIBLE FORWARD. THAT TIME DUE
TO UNAVAILABILITY OF SUCH APPLIANCE SIMPLE BITE BLOCK WERE
CONSTRUCTED WITH AN INCLINED PLANE OF 90° WITH INCISORS EDGE TO
EDGE WITH 2MM OF VERTICAL SEPARATION.
FORTUNATELY, THE YOUNG PATIENT SUCCESSFULLY MADE AN EFFORT TO
WEAR THE APPLIANCE AND THEN THIS TECHNIQUE CAME INTO BEING.

60. HISTORY
THE FIRST TWIN BLOCK APPLIANCES WERE FITTED ON 7TH
SEPTEMBER1977 IN THE SAME PATIENT WHOSE AGE WAS 8 YRS, 4 MONTHS
AND IN A SPAN OF 9 MONTHS, OVERJET REDUCED FROM 9 TO 4MM.

61. TWIN BLOCKS
MODIFIED TWIN BLOCKS
CLARK TWIN BLOCKS

62. TWIN BLOCKS

63. CLARK TWIN BLOCKS
DESIGN
BASEPLATE:
- UPPER (UP TO 6S)
- LOWER (UP TO 1/2CUSPS OF 5S)
• EXPANSION:
- A MIDLINE SCREW
- NECESSARY ONLY WHEN COMPENSATORY EXPANSION NEEDED TO ACCOMMODATE LOWER
ARCH AS THE MANDIBLE TRANSLATES FORWARD.

64. CLARK TWIN BLOCKS
DESIGN
• RETENTION AND ACTIVE COMPONENT :
- UPPER (ADAMS CLASPS ON 6S AND 4S)
- LOWER (ADAMS CLASPS ON 4S/BALL CLASPS ON ANTERIOR)

65. CLARK TWIN BLOCKS
DESIGN
• RETENTION AND ACTIVE COMPONENT

66. CLARK TWIN BLOCKS
DESIGN
• RETENTION AND ACTIVE COMPONENT
UPPER TORQUE IS ACCEPTABLE
UPPER ANTERIOR CROWDING
UPPER TORQUE IS INCREASED AND/OR UPPER ANTERIOR
SPACING
UPPER

67. CLARK TWIN BLOCKS
DESIGN
• RETENTION AND ACTIVE COMPONENT
LOWER
DEEP OB
NORMAL INCLINATION

68. TWIN BLOCKS
DESIGN
• OCCLUSAL BLOCKS:
- POSITION OF THE INCLINED PLANE IS DETERMINED BY THE LOWER
BLOCK,
- LOWER “FROM MID-CUSP OF LOWER 5S TO MESIAL OF LOWER
4S” (PRIMARY MOLARS,
- THINNER BUCCOLINGUALLY IN THE LOWER CANINE REGION
(REDUCING THE BULK TO IMPROVES SPEECH),
- BLOCK ~ 5-6MM THICK BETWEEN MOLARS (MOUTH OPEN
BEYOND FREEWAY SPACE) SO THAT PATIENT CANNOT RETURN TO
FORMER DISTAL OCCLUSION,
- UPPER “FROM 6S TO MESIAL OF 5S”,
- THE DISTAL PORTION COVERS THE POSTERIOR TEETH IN A WEDGE
SHAPE.

69. - DURING THE EVOLUTION OF THE TECHNIQUE…THE
ANGULATIONS USED WERE 45 DEGREE.
DRAWBACKS OF 45 ANGULATIONS LEAD TO
POSTERIOR OPENBITE.
- AN ANGLE OF 45 DEGREE ALSO RESULTS IN
EQUAL DOWNWARD AND FORWARD FORCE ON
THE MANDIBULAR DENTITION.
- FINALLY CHANGED TO 70 DEGREE TO APPLY A
MORE HORIZONTAL COMPONENT OF FORCE.
OCCLUSAL INCLINED PLANE
TWIN BLOCKS
DESIGN

70. DESIGN
TWIN BLOCKS
CLASS II DIV.2

71. BITE REGISTRATION
TWIN BLOCKS
• GEORGE BITE GAUGE
RECOMMEND:
• PROJECT BITE GAUGE

72. BITE REGISTRATION
• AIMS TO ACHIEVE:
- REDUCTION OF OVERJET,
- CORRECTION OF DISTAL OCCLUSION,
- MIDLINE CORRECTION
TWIN BLOCKS

73. BITE REGISTRATION
TWIN BLOCKS
GENERAL GUIDELINES:
PATIENT’S PREPARE
- BITE REGISTRATION IS TAKEN NOT MORE THAN 10MM (PREFERABLY 7MM IF OJ IS MORE THAN 10MM -
BEYOND THIS RANGE, THE MUSCLES AND LIGAMENTS CANNOT ADOPT TO ALTERED FUNCTION - PATIENT WILL
TEND TO POSTURE OUT OF THE APPLIANCE),
- THE PATIENT IS MADE TO SIT IN AN UPRIGHT AND NON-STRAINED POSITION.
- THE MANDIBLE IS GUIDED TO THE DESIRED SAGITTAL POSITION.
- THE PATIENT IS ASKED TO PRACTICE PLACEMENT OF THE MANDIBLE AT THE DESIRED SAGITTAL POSITION A FEW
TIMES BEFORE REGISTRATION OF THE BITE.
- THE PATIENT SHOULD BE INSTRUCTED TO OCCLUDE WITH THE MIDLINES COINCIDENT (DENTAL ? SKELETAL)

74. BITE REGISTRATION
TWIN BLOCKS
- A HORSE-SHOE SHAPED WAX BLOCK IS PREPARED.(IT SHOULD BE 2-3MM THICKER THAN THE
PLANNED VERTICAL OPENING).
- THE WAX BLOCK IS PLACED OVER THE OCCLUSAL SURFACE OF THE LOWER CAST AND IS GENTLY
PRESSED SO AS TO FORM THE INDENTATIONS OF THE LOWER BUCCAL TEETH.
- THE WAX BLOCK IS PLACED ON THE LOWER JAW AND THE PATIENT IS ASKED TO BITE AT THE DESIRED
SAGITTAL POSITION.
- IT IS THEN REMOVED AND PLACED ON THE MODELS AND CHECKED.
- IF FOUND ALL RIGHT , THE EXCESS WAX IS TRIMMED OFF.
- THE HARDENED (FINISHED) WAX BLOCK IS AGAIN TRIED IN THE PATIENT’S MOUTH.
GENERAL GUIDELINES:
WAX’S PREPARE

75. BITE REGISTRATION
TWIN BLOCKS

76. BITE REGISTRATION
PA
TIEN
T
B
ITE
W
ITH
INC
ISO
RS
EDG
E
TO
EDG
E
( A
B
O
U
T
O
F
6
M
M
S
E
P
A
R
A
T I O
N
O
F
M
O
LARS)
TWIN BLOCKS

77. FOLD WAX LENGTHWISE TO 1/3 SIZE
TWIN BLOCKS
BITE REGISTRATION

78. TURN
FOLDED
WAX
LENGTHWISE AND
FOLD
ONCE
W
ITH
SPATULA
IN
BETWEEN
TWIN BLOCKS
BITE REGISTRATION

79. Bite Registration
CRIMP LOWER EDGE AGAINST SPATULA
BITE REGISTRATION
TWIN BLOCKS

80. Bite Registration
PATIENT BITE WITH
INCISORS EDGE TO
E D G E ( 2 M M
I N T E A R I N C I S A L
DISTANCE WILL BE
CREATED)
TWIN BLOCKS
BITE REGISTRATION

81. Bite Registration
TWIN BLOCKS
BITE REGISTRATION

82. TWIN BLOCKS
BITE REGISTRATION
SUMMARY
INTER INCISAL CLEARANCE: 2MM
IN FIRST PREMOLAR REGION: 5-6MM
MOLAR REGION: 1- 2MM

83. STAGES OF TREATMENT
FIRST STAGE (ACTIVE STAGE: 6 - 9MONTHS)
- TO CORRECT ANTEROPOSTERIOR RELATIONSHIP FROM SKELETAL CLASS II TO CLASS I.
TWIN BLOCKS

84. TWIN BLOCKS
STAGES OF TREATMENT
SECOND STAGE (SUPPORT PHASE: 4-6 MONTHS)
- SETTLING OF POSTERIOR TEETH INTO OCCLUSION FROM CLASS
II MOLAR RELATIONSHIP TO CLASS I;
- UPPER BITE BLOCKS TRIMMED TO ALLOW ERUPTION OF LOWER
POSTERIOR TEETH;
- LOWER BITE BLOCKS TRIMMED TO LEVEL OCCLUSAL PLANE.
- IN DEEP BITE CASES, TRIM BLOCKS,
- IN OPEN BITE CASES, DO NOT

85. TWIN BLOCKS
STAGES OF TREATMENT
THIRD STAGE (RETENTION PHASE: 9 MONTHS)
- APPLIANCE WEAR IS REDUCED TO NIGHTTIME WEAR ONLY WHEN THE OCCLUSION
IS FULLY ESTABLISHED.

86. TREATMENT PROTOCOL
TWIN BLOCKS
•FIRST VISIT: TWIN BLOCKS ARE FITTED AND INSTRUCTIONS ARE GIVEN TO THE PATIENT
•INITIAL ADJUSTMENT-AFTER TEN DAYS,
•ADJUSTMENT VISIT AFTER FOUR WEEKS,
•ROUTINE ADJUSTMENT-TIME INTERVAL IS SIX WEEKS,

87. TREATMENT PROTOCOL
TWIN BLOCKS
- WORN AT ALL TIMES INCLUDING EATING? AND SLEEPING,
- IT IS IMPORTANT FOR THE PATIENT TO UNDERSTAND THAT WEARING TWIN BLOCKS FOR
EATING INCREASES THE ORTHOPEDIC FORCES AND IMPROVES THE RESPONSE TO
TREATMENT; THIS MAKES IT A TRUE FUNCTIONAL APPLIANCE,
- REMOVED ONLY FOR BRUSHING OF TEETH AND ACTIVE SPORTING ACTIVITIES,

88. TREATMENT PROTOCOL
TWIN BLOCKS
•REACTIVATION BY ADDITION OF ACRYLIC ON THE ANTERIOR SURFACE OF THE UPPER
BITE BLOCK,
•IT MAY BE NECESSARY TO TRIM OR RELIEVE THE FLANGE THE LOWER APPLIANCE,
LINGUAL TO THE LOWER INCISORS, TO AVOID SOFT TISSUE IRRITATION,
•THE UPPER MIDLINE SCREW IS CONTINUOUSLY TURNED A ONE-QUARTER TURN (OR 2
TIMES)EVERY WEEK TO 10 DAYS UNTIL THE ARCH WIDTH IS ADEQUATE TO
ACCOMMODATE THE LOWER ARCH IN ITS CORRECTED POSITION,
•FINISHING MAY BE UNDERTAKEN WITH FIXED APPLIANCES.

89. BENEFITS OF PROGRESSIVE MANDIBULAR ADVANCEMENT
- GRADUAL TRAINING OF THE PROTRACTOR MUSCLES OF THE MANDIBLE.
- ENHANCED MANDIBULAR GROWTH DUE TO REPEATED STIMULATION OF THE
LATERAL PTERYGOID MUSCLE.
- REDUCED TOOTH MOVEMENT DUE TO THE GENERATION OF THE REDUCED
VISCOELASTIC FORCES.
- PHIL BANKS ET AL IN 2004 EVALUATED THE EFFECTIVENESS OF INCREMENTAL AND
MAXIMUM BITE ADVANCEMENT DURING TREATMENT OF CLASS II DIVISION 1
MALOCCLUSION WITH THE TWIN-BLOCK APPLIANCE. THEY FOUND THAT INCREMENTAL
BITE ADVANCEMENT PRODUCED NO ADVANTAGES OVER MAXIMUM ADVANCEMENT.
TWIN BLOCKS

90. ADVANTAGES OF TWIN BLOCKS TREATMENT
- COMFORTABLE: PATIENT ABLE TO EAT, SPEAK
- AESTHETIC: APPLIANCE NOT OBVIOUS
- MANDIBLE ABLE TO MOVE FREELY
- COMPLIANCE – CAN BE REMOVABLE OR TEMPORARILY CEMENTED
- IMPROVED FACIAL APPEARANCE
- NORMAL SPEECH NORMAL SPEECH
- EASY TO MANAGE CLINICALLY
- NOT EASILY BREAKABLE
- ALLOWS INDEPENDENT ARCH DEVELOPMENT
- IMPROVEMENT OF VERTICAL HEIGHT
- ALLOWS FOR ASYMMETRICAL CORRECTION
- RAPID AND EFFICIENT CORRECTION OF SKELETAL DISCREPANCY AND MALOCCLUSION
TWIN BLOCKS

91. - TREATMENT CAN BE UNDERTAKEN FROM CHILDHOOD TO EARLY ADULTHOOD
- MAY BE INTEGRATED WITH FIXED APPLIANCES
- TREATMENT OF TMJ DYSFUNCTION: SPLINT ALLOWS DISPLACED DISC TO BE RECAPTURED
- TREATMENT OF SLEEP APNEA: INCREASES AIRWAY SPACE
TWIN BLOCKS
ADVANTAGES OF TWIN BLOCKS TREATMENT

95. •CHINTAKANON ET AL (2000) FOUND THAT LATERAL PTERYGOID MUSCLE WAS NOT
RESPONSIBLE FOR NEW POSITION OF MANDIBLE AFTER TREATMENT WITH CLARK'S TWIN
BLOCK. IT IS DUE TO DISPLACEMENT OF MANDIBLE BY CONDYLAR GROWTH AND
SURFACE REMODELING OF FOSSA.
•THE MUSCLES ARE THE PRIME MOVERS IN GROWTH, FOLLOWED BY BONE REMODELLING
AS A SECONDARY RESPONSE. HENCE MUSCLE FUNCTION MUST BE ALTERED OVER A
SUFFICIENT PERIOD OF TIME TO ALLOW ADAPTIVE BONE REMODELLING CHANGES TO
OCCUR, IN ORDER TO REPOSITION THE CONDYLE IN THE GLENOID FOSSA. (MCNAMARA
JA. NEUROMUSCULAR AND SKELETAL ADAPTATIONS TO ALTERED FUNCTION IN
OROFACIAL REGION. AJO 1973)
• MAJOR ADVANTAGE OF USING TWIN BLOCKS WAS THAT IT COULD BE
WORN 24 HOURS, HENCE THE MASTICATORY FORCES CAN BE
TRANSMITTED VIA THE APPLIANCE TO THE DENTITION FROM WHERE THEY
ARE TRANSMITTED TO THE BONY TRABACULAE ACCORDING TO WOLFS
LAW, INFLUENCING THE RATE OF GROWTH AND THE TRABACULAE
STRUCTURE OF THE SUPPORTING BONE.

96. ABSTRACT
FUNCTIONAL APPLIANCES HAVE BEEN USED FOR OVER 100 YEARS IN ORTHODONTICS TO CORRECT
CLASS II MALOCCLUSION. DURING THIS TIME NUMEROUS DIFFERENT SYSTEMS HAVE BEEN
DEVELOPED OFTEN ACCOMPANIED BY CLAIMS OF MODIFICATION AND ENHANCEMENT OF
GROWTH. RECENT CLINICAL EVIDENCE HAS QUESTIONED WHETHER THEY REALLY HAVE A LASTING
INFLUENCE ON FACIAL GROWTH, THEIR SKELETAL EFFECTS APPEARING TO BE SHORT TERM.
HOWEVER, DESPITE THESE FINDINGS, THE CLINICAL EFFECTIVENESS OF THESE APPLIANCES IS
ACKNOWLEDGED AND THEY CAN BE VERY USEFUL IN THE CORRECTION OF SAGITTAL ARCH
DISCREPANCIES. THIS ARTICLE WILL DISCUSS THE CLINICAL USE OF FUNCTIONAL APPLIANCES, THE
UNDERLYING EVIDENCE FOR THEIR USE AND THEIR LIMITATIONS.

98. - THEY FOUND THAT TWIN BLOCK APPLIANCE PRODUCED GREATER SKELETAL EFFECTS IN TERMS
OF MANDIBULAR ADVANCEMENT AND GROWTH STIMULATION WHILE THE FORSUS CAUSED
SIGNIFICANT PROCLINATION OF THE MANDIBULAR INCISORS.

100. TWIN BLOCK WITH THE HERBST APPLIANCE (O’BRIEN ET.AL., EFFECTIVENESS OF TREATMENT FOR
CLASS II MALOCCLUSION WITH THE HERBST OR TWIN BLOCK APPLIANCE: A RANDOMIZED
CONTROLLED TRIAL. AM J ORTHOD DENTOFACIAL ORTHOP 2003; 124: 128–37).
SUCCESS RATES
A REPORTED FAILURE FOR 12.9% FOR HERBST AND 33.6% FOR TWIN BLOCK:
REASONS:
- FREE TREATMENT,
- POOR SOCIO-ECONOMIC BACKGROUND MAY BE FACTORS IN POOR COOPERATION AND FAILURE TO COMPLETE
TREATMENT,
- APPLIANCE DESIGN MAY ALSO BE A FACTOR IN PATIENT ACCEPTANCE: (BULKY ACRYLIC BLOCKS),
- TWIN BLOCKS CAN BE REMOVED AND HERBST APPLIANCES ARE CEMENTED IN THE MOUTH,

101. SUCCESS RATES
IN OTHER STUDIES, THE FAILURE TO COMPLETE RATE WAS REPORTED AS
•8.4% (CLARK, 1995)
•9% (ILLING ET.AL., 1998)
•15% (HARRADINE AND GALE, 2000)
•6.7% (CLARK WJ. NEW HORIZONS IN ORTHODONTICS AND DENTOFACIAL ORTHOPAEDICS. THESIS SUBMITTED
FOR THE DEGREE OF DDSC TO DUNDEE UNIVERSITY, 2010)

102. CONCLUSION
- THIS ARTICLE IDENTIFIES COMMON ERRORS IN TWIN BLOCK DESIGN AND MANAGEMENT, WHICH
INFLUENCE THE RATE OF FAILURE TO COMPLETE TREATMENT.
- A PROTOCOL IS DESCRIBED TO IMPROVE EFFICIENCY IN THE APPLICATION OF TWIN BLOCK TECHNIQUE.
- FACIAL APPEARANCE IMPROVES IMMEDIATELY WHEN TWIN BLOCKS ARE INSERTED.
- AESTHETIC TWIN BLOCK DESIGN ENCOURAGES PATIENTS TO WEAR THE APPLIANCES FULL TIME.
-
• THESE ARE IMPORTANT FACTORS IN PATIENT MOTIVATION AND COOPERATION.
- T H E A U T H O R ’ S W E B S I T E I S
WWW.TWINBLOCKS.COM AND CONTAINS FURTHER
INFORMATION ON RECENT DEVELOPMENTS,
INCLUDING FIXED TWIN BLOCKS.

103. CONCLUSION

104. CONCLUSION
WE NEED TO NOT IGNORE
T H E I M P O R T A N C E O F
DENTOFACIAL ORTHOPEDIC
TECHNIQUES IN ACHIEVING THE
GOALS BY GROWTH GUIDANCE
DURING THE FORMATIVE YEARS
O F FA C I A L A N D D E N TA L
DEVELOPMENT.

105. @nhalhamlan
@saudibraces
nasiralhamlan
@nasiralhamlan