Choufani, J.-M. E., Rinchuse, D. J., Boggio, A., Cozzani, M., Manni, A., & Gastaldi, G.
CRANIO® · 2025
Challenges the clinical orthodoxy that maxillary canines are always worth heroic treatment efforts. Provides a framework for identifying when extraction of a severely displaced or impacted maxillary canine — with first premolar substitution — is biomechanically sound, functionally equivalent, and the better long-term choice for the patient. Argues there is no robust scientific support for the concept of canine-protected occlusion as a categorical contraindication to extraction.
Orthodontic Biomechanics — In Preparation13 manuscripts
First-principles computational mechanics derived from a validated open engine. Each result regenerates from a reproducible script; no numbers are hand-transcribed. Manuscripts are in preparation for peer-reviewed submission. The underlying engine is available through the First Principles Designer.
Arc 1Force Series6 manuscripts
P1
Anchorage is mechanics-dominated: a first-principles resolution of the full indeterminate cantilever system
Periodontal support is second-order and bone type negligible in determining anchorage outcomes — clinician-controlled mechanics is the dominant variable. Resolves the indeterminate force-system problem set aside in prior literature.
Draft complete◆◆
P3
There is no single optimal orthodontic force: the force optimum is a PDL-pressure threshold proportional to root surface area
No universal optimal force exists. The threshold at which PDL compression reaches capillary pressure equals 0.26 g·mm−2 × root surface area — modulus-invariant and patient-specific. Returns diminish beyond it.
Draft complete◆◆◆
#2
Root surface area as anchorage currency: why Tweed classes are bands of one ratio and absolute anchorage requires a TAD
Root area simultaneously sizes safe force and anchorage capacity. The Tweed A/B/C classification reduces to bands of a single root-area ratio. Tooth-borne anchorage loss is never zero; skeletal (TAD) anchorage is the only true absolute.
Draft complete◆◆◆
#3
PDL-stress efficiency peaks at bodily translation: a first-principles account of moment-to-force ratios and why they matter
Bodily translation maximises the ratio of useful tooth movement to PDL stress. Tipping and root-movement modes concentrate stress and tolerate far less applied force for the same movement target.
Draft complete◆
#5
The efficiency pyramid quantified: treatment efficiency as a product of five weight-free factors
η = ηkinematic × ηuniformity × ηanchorage × ηuncertainty × ηcoupling. Each factor ranges 0–1 with no fitted weights. Whole-arch coupling (continuous arch retains 36%) is folded in; the framework identifies where treatment entropy comes from.
Draft complete◆◆
Cap.
Biomechanics is the lever, the periodontium the envelope: a first-principles framework for orthodontic force systems
Synthesis perspective: the clinically controllable force system is derived from mechanics; the periodontium is the biological envelope that determines the rate and ceiling of response. Cites the companion series and situates it within the broader field.
Living draft
Arc 23D Mechanics5 manuscripts
S27
Anchorage is a tensor, not a scalar: a 6-DOF stiffness account of the indeterminate anchorage problem
Resistance to displacement is a 6×6 PDL stiffness tensor spanning all force and moment degrees of freedom. The scalar Tweed anchorage classification is a projection of this tensor onto one axis. Absolute anchorage requires infinite stiffness in all six DOF — only skeletal.
Draft complete◆◆◆
S30
Trading geometry for force in intrusion: the horizontal-force substitution law Fh = (b/h)·Fv
A horizontal chain or NiTi spring substitutes exactly for the intrusion-arch point-of-application shift, with an irreducible retraction component. A constant-force spring beats a decaying chain between visits. Midline mechanics is the transverse twin of the same relationship.
Draft complete · independently vetted◆◆◆
S28
Closed-form 3D side-effect atlas: yaw, torque, and the engagement gate in cantilever mechanics
Closed-form expressions for all three-dimensional side effects of cantilever loading: yaw = b·Fy, torque = b·Fz, height-invariant. Tip-back leaks yaw only; intrusion leaks torque only. Bracket engagement is the torque gate: a 16×22 wire in a 22-slot fails to engage.
Draft complete · 57-check vet◆◆
S31
Prescription as anchorage: what wire and bracket geometry alone can and cannot do as a differential lever
A full archwire with prescription (including reverse-Rx: flipped incisors, swapped canines) is a real auxiliary-free differential couple. It cannot be a force source: protraction still requires a separate force element. Minimum anchorage in the strict sense therefore still needs an independent force source.
Draft complete · 11-check vet◆◆
S26
Resorption-risk topography: how the centre of rotation sets where PDL compression peaks
The movement type, via the centre of rotation, determines the spatial pattern of PDL compression: tipping concentrates stress at the crest (apex spared); root movement and torque produce concentrated apical peaks; translation is diffuse. Notably, intrusion is spatially uniform — its clinical apical resorption is not an elastic-concentration effect.
Draft complete · 7-check vet◆◆
Arc 3Validation1 manuscript
P2
A reduced-order biomechanics engine reproduces high-fidelity 3D force systems and textbook limits without tuning
The engine reproduces a published three-dimensional V-bend force-system measurement (load-cell data), center of resistance at 42% of root length, and M:F-to-center-of-rotation mapping, with no parameter fitting. Addresses the contemporary validation gap: in-silico models are rarely validated against clinical measurements.
Draft — 10/10 vet checks◆◆
TheoryPeriodontal Control Theory1 manuscript
PCT
The periodontal ligament is the controller, bone the effector: a unified control-theoretic account of tooth movement
A position paper unifying four established findings — PDL elastic equilibrium, perfusion-limited rate response, anchorage as a stiffness tensor, and the mechanostat — into one falsifiable framework with a modulus-invariance spine. Challenges the bone-centric narrative: bone remodeling operates at strain levels 300× below the mechanosensing threshold during orthodontic loading. The PDL, not bone, is the closed-loop controller of tooth position.
A standalone, citable research library comprising 30 modules covering the full finite periodontal-ligament engine, tooth-movement trajectory simulation, resorption-risk modeling, and dental materials physics. Validated against published textbook values for center of resistance, moment-to-force ratios, tipping vs. bodily movement, and rotational mechanics. Every number in the associated manuscripts regenerates from a script against this engine; no results are hand-transcribed. Citation required for research use; commercial and clinical-practice use requires a separate license.
Outside clinical practice, I research the failure modes of classical statistical tools when applied to fat-tailed return distributions — the regime that describes most individual U.S. equities. The work below is a 10-paper series on SSRN covering tail estimation, signal validation, ergodicity, risk measurement, and portfolio epistemology.
FAT_STRUCTURAL and FAT_BINARY stocks share identical Hill estimates yet diverge 13.7 percentage points in expected value — the Hill estimator is not a sufficient statistic for return prospects.
The Hill estimator is formally inconsistent for binary-jump processes; any tail-index computation requires source-of-tail pre-classification to avoid category error.
Two Problems, One Incomplete Fix: Newey-West Corrections Under Fat-Tailed Returns
Newey-West corrects serial correlation but amplifies fat-tail bias; the two sources of invalid inference require separate treatments, not a single adjustment.
A sequential nine-gate gauntlet for distinguishing robust signals from overfitting artifacts, with worked examples drawn from the payoff asymmetry anomaly.
The time-average/ensemble-average gap — ergodicity economics in the Peters sense — is calibrated directly from the empirical tail exponent across the full equity cross-section.
At the empirical median α̂ = 2.69, the MinTRL via Sharpe ratio is approximately 1,100 years; conventional 3–5-year due-diligence windows have formally zero statistical power for most individual equities.
The classical Gaussian drawdown formula breaks for α ≤ 4; a correction factor Φ(α,T) grows with horizon and diverges as α → 2 — risk models that ignore this systematically underestimate drawdown.
FAT_BINARY events (FDA approvals, binary regulatory outcomes) occupy a genuine ontological category distinct from both Black Swans and power-law extremes; a three-category formal taxonomy follows.
Portfolio optimization is not merely imprecise under fat tails — it is epistemically unavailable; an information-theoretic lower bound establishes the barbell as the formally derivable rational response.