In this lecture Dr. William M. Hang presents a longitudinal case of a child with congenitally missing maxillary lateral incisors. He follows the patient from 8 years 8 months to 14 years 5 months, describing normal maxillary expansion and favorable mandibular downward‑forward growth early on. When the patient reaches the stage where space is needed for implants (≈4 mm per side), Dr. Hang demonstrates how easily 2–2.5 mm of space can be opened with modern techniques, yet he explains that many orthodontists traditionally close the spaces by moving the canines forward and retracting the incisors to avoid implants. He argues that this “path of least resistance” is not benign: it places excessive reciprocal forces on the central incisors, impedes mandibular forward growth, and ultimately redirects growth vertically. Using a tug‑of‑war analogy, he illustrates the biomechanical implausibility of pulling the canines forward with the incisors as anchors. He critiques the claim that traditional mechanics can achieve this without auxiliary anchorage, suggesting that only temporary anchorage devices (TADs) or extra‑oral appliances (e.g., face masks) could realistically provide the needed force vectors. The case concludes that closing the spaces compromised mandibular development, underscoring the importance of preserving space for prosthetic replacement rather than forcing retraction.
Chapters
This is gonna show you what happens when you retract. Here's a kid who's missing lateral incisor teeth. Alright? And so between 8 years, 8 months and 12 years, 10 months, the orthodontist expands his maxilla, which is a good thing. And watch what happens His mandible is growing downward and forward. Can you see that? That's favorable. That's the way we are taught that patients grow. And when they have lip-together posture, their tongue to the palate, that's the way they're gonna grow. But this guy had sinned badly and was missing lateral incisors. And so, here we go. He's got about 4 millimeters of space for each lateral incisor. How hard is it for me to open up 2, 2.5 millimeters to get space for an implant? I can do that with my eyes closed now. Now I used to close the spaces like this because I'd say just like all the orthodontists, oh Johnny, we can save you from an implant. Save you from an implant. And we can have the argument about how well the restorative dentist can make the cuspid look like the lateral incisor. I don't care. Do I really care about that? No, I care what's gonna happen to the face. That's what I care about. And my point is it's not innocuous. It's not okay. So, they take the path of least resistance and close the spaces up. We're gonna bring the cuspids forward, right? Is that what they're gonna do, bring the cuspids forward? Right. That's what they tell you though, right? We'll bring the cuspids forward. And I always say, great. How many of you played tug-of-war on the playground, okay, when you were a kid in grade school? That was before it was illegal to have anyone win and lose. You couldn't lose. It's okay. So we— I pick the big guys. I pick you, you're a big guy. And then the little weaselly one that weighs 20 pounds still and he's 3rd grade, you know, he's there, he gets picked last because he's not gonna be able to pull. I'm picking the big guys. So let's think about this in the tug-of-war. You got 2 monster guys here, fairly good one here and here, big monster cuspid, and 2 moderate-sized central incisors. And what you're telling me is these central incisors are gonna hold and drag all these other teeth forward. How's that gonna work? It's insane. You're not bringing the cuspids forward, you're retracting the incisors. And the next time an orthodontist tells you they're gonna bring the cuspids forward, you're gonna say, oh really, I'd like to know how. Does he have temporary anchorage devices anchored out in front of the face and he's gonna pull them all forward? Great, you wanna wear a face mask? Do what you gotta do. But don't tell me with traditional orthodontics you're gonna do that. So now from age 12 years 10 months to 14 years 5 months, he closes the spaces up. And what happens to the growth of the mandible? Notice how much retraction there is. Not a lot, but basically it's like the biggest roadblock ever. So the mandible that was growing forward is now growing vertically.
