Techniques for predictable excellence
Maxillary lateral incisors are some of the most commonly missing teeth, second only
to mandibular premolars.1 When a lateral incisor is missing, there is a high aesthetic
requirement to make the replacement tooth look natural because of its location in the
aesthetic zone. Currently, there are four options for replacing a missing maxillary lateral
Weighing the pros and cons
The first three options necessitate precise orthodontic treatment so that the space for
the lateral incisor restoration is 80% of the width of the maxillary central incisor. Most
maxillary central incisors are between 8 and 9 mm in width; therefore, the appropriate
width for a maxillary lateral incisor should be 6.4–7.2 mm.
- Removable partial denture (RPD).
- Fixed partial denture (FPD), or “bridge.”
- Dental implant.
- Cuspid substitution.
An advantage of an RPD is that fabrication is relatively inexpensive. An RPD can be
as simple as a resin pontic tooth affixed to an acrylic or “slipcover” retainer. However, this
style of RPD is typically not very durable, and is often taken out for meals. This can cause
an embarrassing situation and increases the risk of loss or damage of the RPD if it is left on
a napkin or stuffed in a pocket. A more elaborate and durable cast RPD can be fabricated at
an increased cost, but this style of RPD often requires creating preparations within enamel
to serve as rests to stabilize the appliance. For these reasons, RPDs are not considered a
long-term treatment of choice for most patients.
An FPD requires some preparation of adjacent teeth, depending on the design. These
designs vary from a conservative Maryland bridge to a cantilever pontic bridge to a conventional
crown-supported bridge. No matter the design of the FPD, careful attention must
be paid to the gingival architecture and development of papilla. This is often most successfully
accomplished with an ovate pontic to tissue-mold the edentulous space into natural-appearing gingival contours around
the pontic. Tissue molding must be carried
out under the careful hands of a skilled restorative
dentist, and sometimes requires
the assistance of soft tissue grafting to be
successful. Another challenge of an FPD is
cleansibility, and studies have shown that
there is more gingival inflammation in
FPD patients than in patients with natural
Dental implants have long been considered
the gold standard for replacing a
missing tooth. However, dental implants
cannot be placed in growing teens, because
dentofacial growth is not complete. If a
dental implant is placed before growth is
complete, the implant will eventually appear
to be in infraocclusion as the adjacent
teeth continue to grow and change around
it.3 In fact, even in mature adults, studies
have shown that the face is still changing
and growing through the fourth decade of
life and infraocclusion of dental implants
in the aesthetic zone can still occur.4 Another
challenge of dental implants in the
aesthetic zone is that more than half of
them show noticeable color change of the
overlying gingiva after five years.5
On the cusp...ids
Cuspid substitution allows a natural
tooth to remain in the aesthetic zone; however,
there are key considerations to optimize
the option’s aesthetics and function.
Before brackets are bonded to the cuspid
that will serve as a lateral incisor, the
cuspid should be sculpted with burs and
composite to resemble a lateral incisor of
the appropriate size: 80% of the width and
length of the central incisor (Figs 1a–1k).
Figs. 1a and 1b: Left maxillary cuspid before and after lateralization.
Figs. 1c and 1d: Flattening the facial surface with a diamond disc bur.
Figs. 1e and 1f: Reducing the width mesially and distally with a straight
Figs. 1g and 1h: Reducing the incisal edge with a diamond disc bur.
Fig. 1i: Reducing the lingual prominence with a diamond disc bur to
produce a flat lingual surface.
Figs. 1j and 1k: Adding composite to the mesiofacial and distofacial
line angles and creating proper mesioincisal and distoincisal contours
to simulate a lateral incisor.
A step-by-step guide:
Push, don’t pull
- Flatten the facial surface with a
diamond disc bur.
- Reduce the width mesially and
distally with a straight diamond bur.
- Reduce the incisal edge with a
diamond disc bur.
- Reduce the lingual contour with a
diamond disc bur.
- Add composite to the mesiofacial
and distofacial line angles and create
proper mesioincisal distoincisal
contours to simulate a lateral incisor.
A common complaint of dentists is that
cuspid substitution cases appear too narrow.
I believe this is often because of the use of
elastic chains to close spaces between maxillary
centrals and cuspids. Elastic chains
constrict, whereas open-coil springs expand.
Use open-coil springs between the first premolar
and the cuspid to close any space between
the new “lateral incisor” and the central
incisor. Open-coil springs can also assist
in centering midlines in unilateral missing
Intrude the first premolar
A maxillary premolar is approximately
3 mm shorter than a maxillary cuspid.
Therefore, to achieve appropriate gingival
architecture, the bracket of the first premolar
should be moved 3 mm occlusally
when it is first bonded. This will provide
adequate time for the premolar to intrude
as wire sizes are increased during treatment.
Once the premolar is positioned
in a Class I relationship with the lower
cuspid, it will need composite restoration
to lengthen it to its appropriate cuspid
length and contour. Eventually, the tooth
should be restored with a more definitive
long-term restoration such as a porcelain
veneer or crown.
Place the new “cuspid” in group function
To protect the smaller root of the premolar serving in the cuspid position, group function
occlusion is advised so that the lateral excursive forces can be shared among all teeth
in the buccal segment.
Use a Y-bar to protract maxillary posterior teeth
Once the maxillary midline is on to the face, the new “lateral incisor(s)” are
properly aligned, and all incisors are adequately coupled with the lower incisors, then
it is time to lock them in place via indirect palatal anchorage. Two 1.5-by-9 mm Spider
Screw TADs with self-ligating heads are placed in the midline of the palate approximately
10 mm apart, and an impression is made so that a 0.019-by-0.025-inch
stainless steel Y-bar can be fabricated and locked into place (Fig. 2). This Y-bar
is then adhered to the lingual surfaces of all four maxillary incisors, providing absolute
indirect skeletal anchorage. Now remaining posterior spaces can be efficiently closed
on a broad 0.019-by-0.025-inch stainless wire by using facial and lingual elastic chains.
The lingual elastic chains are attached to lingual buttons bonded to all posterior teeth,
and the elastic chains are terminated onto hooks integrated within the Y-bar.
Fig. 2: Y-bar fabricated with 0.016-by-0.022-inch
stainless steel wire secured into two
palatal self-ligating 1.5-by-9 mm spider screw TADs. Note lingual
buttons on premolars.
Flip the 6s
When cuspid substitution is planned for missing maxillary lateral incisors, it typically
results in the molars finishing in a Class II relationship. This means that the palatal cusp
of the upper first molar will rest on the marginal ridges of the mandibular first molar and
second premolar, rather than in the central fossa of the mandibular first molar.
Therefore, the palatal cusp of the maxillary first molar must be more occlusal than it
normally is. So, more facial root torque is needed. Similarly, less rotation is desired on the
maxillary first molar because of its relationship with both the mandibular second premolar
and first molar.
The bracket that has more facial root torque and less rotation is the mandibular first
molar bracket of the contralateral arch (typically 22 degrees of torque and 0 degrees of
rotation). This will aid in first molar fi t and finish.
When the aforementioned principles are consistently applied, cuspid substitution cases
can predictably provide optimal aesthetics combined with a natural tooth in the esthetic
zone which will grow, change, and induce bone formation as the patient continues to grow and change. Eventually the provisional composite restorations can be replaced with more
definitive porcelain restorations, enhancing the long-term aesthetic prognosis.
A 10-year-old patient presented with a chief complaint of maxillary spacing and missing
maxillary lateral incisors #7 and #10 (Fig. 3a). She had a deep bite and an Angle’s Class
II molar and canine relationship. Clinical examination of her short clinical crowns hinted at
early signs of altered passive eruption, but because of her young age and growth potential,
a definitive diagnosis could not be made at that time. The cephalometric radiograph (Fig.
3b) revealed that she was brachycephalic and slightly bimaxillary retrusive. However,
her maxillary incisal angulation was ideal. The panoramic radiograph (Fig. 3c) was
unremarkable, with the exception of the missing teeth #7 and #10.
The patient was treatment-planned for cuspid substitution, converting the maxillary
cuspids to lateral incisors and the maxillary premolars into cuspids. The molars would remain
Angle’s Class II.
The cuspid conversion procedure described earlier was followed as tooth #6 was reshaped
to resemble missing tooth #7 and tooth #11 was reshaped to resemble #10. Brackets with an
0.020-by-0.026-inch slot (Norris 20/26) were placed, paying particular attention to move
the maxillary first premolar brackets 3 mm to the occlusal to begin intruding those teeth that
would eventually serve as maxillary cuspid teeth. Mandibular molar brackets with 0 degrees of
rotation and 20 degrees of torque were placed on the maxillary molars to enhance the fit of the
molars in an Angle’s Class II relationship. Bite turbos were placed to disclude her occlusion.
A 0.014-inch Norris Extra Broad NiTi archwire was placed at the initial visit (Figs. 4a–4c).
The normal Norris 20/26 system archwire progression was followed, and an 0.018-by-
0.018-inch Norris Extra Broad NiTi wire was placed at her next appointment (Figs. 5a–5c).
Subsequently, a 0.019-by-0.025-inch NiTi wire was placed, which completed the intrusion
of the maxillary first premolars, continued arch development and provided a strong enough
wire on which excess spaces could begin to close using elastic chains and Class III elastics
Once the maxillary first premolars reach an ideal Class I relationship with the lower
canines, then the orthodontic brackets are removed from them and composite resin
is added to convert them to canines. Note that when the brackets are replaced after the
bonding procedure, they are sometimes placed in an even further incisal position to further
intrude the new “canines” to idealize the
final gingival architecture. (Figs. 7a–7c). Eventually, the canines are positioned in
a group function role, whereby the posterior
teeth share lateral excursive forces with the
new maxillary premolar that is serving as a
Upon completion of orthodontic
treatment, bonded lingual retainers were
placed and the patient was fitted with
vacu-form retainers for nighttime wear
(Figs. 8a–8d). The patient and parent
were informed that she will likely need
osseous crown lengthening to establish ideal
posterior gingival heights and that long-term
restorations such as porcelain veneers
on the maxillary laterals and cuspids are also
indicated once growth is complete. Normally
the timing of the crown lengthening and
final restorations occurs after the age of 16
in females and after the age of 18 in males.
1. Zilberman, Y, Cohen, B, Becker, A. “Familial trends in palatal
canines, anomalous lateral incisors, and related phenomena.”
Eur J Orthod 1990; 12:135-139.
2. Robertsson, S, Mohlin, B. “The congenitally missing upper lateral
incisor. A retrospective study of orthodontic space closure versus
restorative treatment.” Eur J Orthod 2000;22:697-710.
3. Thilander, et al. “Single implants in the upper incisor region and
their relationship to adjacent teeth. An 8-year follow-up study.”
ClinOral Implants Res 1999;10:346-355.
4. Bernard, et al. “Long-term vertical changes of the anterior
maxillary teeth adjacent to single implants in young and mature
adults. A retrospective study.” J Clin Periodontol 2004;1024-
5. Graber, DA, Salama, MA, Salama, H. “Immediate tooth replacment.”
Compend Contin Educ Dent 2001;22:210-8.
Next month: Go inside the practice
In our October 2021 issue,
Dr. Robert “Tito” Norris gives us
a tour of Stone Oak Orthodontics,
his practice in San Antonio, Texas,
and discusses how his mechanical
engineering background helped
him succeed as an orthodontist.
Dr. Robert “Tito”
Norris is a 1992
graduate of the
at San Antonio
Dentistry. Norris completed a general
practice residency at the VA Medical
Center in Washington, D.C., followed by
orthodontic specialty training at Howard
University, graduating as valedictorian
with the highest GPA in the program’s
After serving as a U.S. Air Force
orthodontist in Misawa, Japan, Norris
returned to San Antonio in 1998
and opened a private orthodontic
practice. He holds several patents and
trademarks, and is the inventor of
the Norris 20/26 Passive Self-Ligating
Norris is board-certified by the American
Board of Orthodontics, and is a member
of 10 dental organizations and study
clubs. He lectures internationally on
topics including aesthetics, efficiency,
sustainability, customer service,
accelerated treatment and aligner