# -*- coding: utf-8 -*-
from reportlab.lib.pagesizes import A4
from reportlab.lib.units import inch, cm
from reportlab.lib import colors
from reportlab.lib.styles import getSampleStyleSheet, ParagraphStyle
from reportlab.lib.enums import TA_JUSTIFY, TA_CENTER, TA_LEFT
from reportlab.platypus import (SimpleDocTemplate, Paragraph, Spacer, Table, TableStyle,
                                 PageBreak, ListFlowable, ListItem, HRFlowable)
from reportlab.pdfbase.pdfmetrics import stringWidth

OUT = "/tmp/workspace/inlay-onlay-essay/output/Critical_Appraisal_Metallic_NonMetallic_Inlays_Onlays.pdf"

styles = getSampleStyleSheet()

title_style = ParagraphStyle('TitleX', parent=styles['Title'], fontSize=18, leading=22,
                              spaceAfter=6, textColor=colors.HexColor('#1a3d6d'))
subtitle_style = ParagraphStyle('Subtitle', parent=styles['Normal'], fontSize=11, leading=14,
                                 alignment=TA_CENTER, textColor=colors.HexColor('#555555'), spaceAfter=14)
h1 = ParagraphStyle('H1X', parent=styles['Heading1'], fontSize=14.5, leading=18,
                     spaceBefore=16, spaceAfter=8, textColor=colors.HexColor('#1a3d6d'),
                     borderPadding=0)
h2 = ParagraphStyle('H2X', parent=styles['Heading2'], fontSize=12.5, leading=16,
                     spaceBefore=10, spaceAfter=6, textColor=colors.HexColor('#2c5282'))
h3 = ParagraphStyle('H3X', parent=styles['Heading3'], fontSize=11.5, leading=14,
                     spaceBefore=6, spaceAfter=4, textColor=colors.HexColor('#333333'), fontName='Helvetica-BoldOblique')
body = ParagraphStyle('BodyX', parent=styles['BodyText'], fontSize=10.5, leading=15,
                       alignment=TA_JUSTIFY, spaceAfter=8)
bullet = ParagraphStyle('BulletX', parent=body, leftIndent=14, spaceAfter=4, bulletIndent=4)
small = ParagraphStyle('SmallX', parent=styles['Normal'], fontSize=8.5, leading=11,
                        textColor=colors.HexColor('#666666'))
tblhead = ParagraphStyle('TblHead', parent=styles['Normal'], fontSize=9.3, leading=11.5,
                          textColor=colors.white, fontName='Helvetica-Bold', alignment=TA_CENTER)
tblcell = ParagraphStyle('TblCell', parent=styles['Normal'], fontSize=9, leading=11.5)

story = []

def P(text, style=body):
    story.append(Paragraph(text, style))

def bullets(items, style=bullet):
    flow = []
    for it in items:
        flow.append(ListItem(Paragraph(it, style), leftIndent=14, value='bullet', bulletColor=colors.HexColor('#1a3d6d')))
    story.append(ListFlowable(flow, bulletType='bullet', start='circle'))
    story.append(Spacer(1, 6))

def hr():
    story.append(HRFlowable(width="100%", thickness=0.7, color=colors.HexColor('#1a3d6d'), spaceBefore=4, spaceAfter=10))

def make_table(header, rows, col_widths):
    data = [[Paragraph(h, tblhead) for h in header]]
    for r in rows:
        data.append([Paragraph(str(c), tblcell) for c in r])
    t = Table(data, colWidths=col_widths, repeatRows=1)
    t.setStyle(TableStyle([
        ('BACKGROUND', (0,0), (-1,0), colors.HexColor('#1a3d6d')),
        ('GRID', (0,0), (-1,-1), 0.5, colors.HexColor('#999999')),
        ('VALIGN', (0,0), (-1,-1), 'TOP'),
        ('ROWBACKGROUNDS', (0,1), (-1,-1), [colors.white, colors.HexColor('#eef3fa')]),
        ('TOPPADDING', (0,0), (-1,-1), 5),
        ('BOTTOMPADDING', (0,0), (-1,-1), 5),
        ('LEFTPADDING', (0,0), (-1,-1), 6),
        ('RIGHTPADDING', (0,0), (-1,-1), 6),
    ]))
    story.append(t)
    story.append(Spacer(1, 10))

# ---------------- TITLE PAGE / HEADER ----------------
P("Critical Appraisal of Metallic and Non-Metallic Inlays and Onlays", title_style)
P("An Essay in Operative Dentistry / Prosthodontics  |  Long-Answer / 50-Mark Format", subtitle_style)
hr()

# ---------------- 1. INTRODUCTION ----------------
P("1. Introduction", h1)
P("Inlays and onlays are indirect intracoronal and extracoronal restorations fabricated outside the mouth "
  "(on a die/cast, or by CAD-CAM milling) and subsequently luted into a prepared cavity. An <b>inlay</b> restores "
  "the occlusal and proximal surfaces of a tooth without covering the cusp tips, staying entirely within the "
  "confines of the cusps. An <b>onlay</b> extends beyond the inlay outline to cap one or more cusps, providing "
  "cuspal coverage and protecting weakened tooth structure against fracture under occlusal load. Both restorations "
  "occupy an intermediate position between simple direct fillings and full-coverage crowns, offering a conservative "
  "yet durable option for moderate to large carious lesions, failed restorations, cracked-tooth syndrome, and "
  "post-endodontic restoration of premolars and molars.", body)
P("Historically, inlays and onlays were synonymous with <b>cast gold</b> alloy restorations popularised by G.V. "
  "Black and refined by Taggart's lost-wax casting technique (1907). With the evolution of adhesive dentistry, "
  "high-strength dental ceramics, and CAD-CAM technology, the restorative options have expanded to include a wide "
  "spectrum of <b>non-metallic</b> materials &mdash; composite resins and ceramics &mdash; that satisfy the modern "
  "demand for tooth-coloured, biomimetic, and minimally invasive dentistry. A critical appraisal of these two broad "
  "categories requires an evaluation against biological, mechanical, esthetic, technical, and economic criteria, "
  "which forms the substance of this essay.", body)

# ---------------- 2. DEFINITIONS & INDICATIONS ----------------
P("2. Definitions, Indications and Contraindications", h1)
P("2.1 Definitions", h2)
bullets([
  "<b>Inlay:</b> An indirect restoration that restores one or more surfaces of a tooth, situated within and bounded by the cusps, not extending to cover them.",
  "<b>Onlay:</b> An indirect restoration that restores one or more surfaces and extends to cover one or more cusp tips, thereby splinting and protecting the remaining tooth structure.",
  "<b>Overlay / Table-top restoration:</b> A modern extension of the onlay concept that covers the entire occlusal table with minimal axial extension, frequently used with adhesive ceramic or composite systems."
])
P("2.2 Indications", h2)
bullets([
  "Moderate to large proximal-occlusal carious lesions or defective restorations where a direct filling would be under-supported or prone to marginal leakage.",
  "Restoration of endodontically treated posterior teeth with sufficient remaining coronal structure, as a conservative alternative to a full crown.",
  "Cracked-tooth syndrome and cuspal fracture, where an onlay splints the cusps and prevents further propagation of the crack.",
  "Replacement of failing amalgam or composite restorations with weakened marginal ridges or isthmuses.",
  "Patients desiring superior wear resistance (metallic) or esthetics (non-metallic) compared to direct restorations.",
  "High caries-risk-free patients where cost and technique sensitivity of ceramic/composite indirect work are acceptable."
])
P("2.3 Contraindications", h2)
bullets([
  "High caries activity or poor oral hygiene (relative contraindication, particularly for ceramic due to marginal microleakage risk over time).",
  "Very young patients with large pulp chambers (risk of pulp exposure during preparation) or short clinical crowns preventing adequate retention form.",
  "Bruxism/parafunction is a relative contraindication for brittle ceramics (risk of bulk fracture) unless adequately thick and supported; metal or reinforced ceramics preferred.",
  "Insufficient isolation for adhesive bonding (a contraindication for resin-bonded ceramic/composite onlays, though less critical for cast metal cemented conventionally)."
])

# ---------------- 3. CLASSIFICATION ----------------
P("3. Classification of Materials", h1)
P("For the purpose of critical appraisal, inlay/onlay materials are broadly divided into two classes:", body)
bullets([
  "<b>Metallic:</b> Type II/III/IV cast gold alloys, silver-palladium alloys, base-metal (nickel-chromium, cobalt-chromium) alloys, and titanium.",
  "<b>Non-metallic:</b> Direct and indirect composite resins; dental ceramics (feldspathic/silicate porcelain, leucite-reinforced glass-ceramic, lithium-disilicate glass-ceramic, zirconia-reinforced lithium silicate, polycrystalline zirconia, and resin-matrix CAD-CAM ceramics/hybrid materials such as polymer-infiltrated ceramic network)."
])

# ---------------- 4. METALLIC ----------------
P("4. Metallic Inlays and Onlays: Critical Appraisal", h1)
P("4.1 Cast Gold Alloys", h2)
P("Cast gold (Type II and III alloys, gold content approximately 60-90%) remains, on strict engineering and "
  "longevity grounds, the benchmark against which every newer material is measured. Its performance is best "
  "appraised under distinct criteria:", body)

P("Biological / Periodontal", h3)
P("Gold alloys are chemically inert, highly biocompatible, and produce the smoothest achievable margins after "
  "burnishing, minimising plaque accumulation and gingival irritation. Corrosion resistance is excellent because "
  "noble alloys resist oxidation in the oral environment.", body)

P("Mechanical", h3)
bullets([
  "Modulus of elasticity and compressive strength closely approximate those of enamel and dentine, so occlusal forces are transmitted favourably without causing cuspal flexure or fracture of opposing/adjacent natural tooth structure.",
  "Ductility permits burnishing of margins to a near-perfect marginal seal (margins can be closed to under 25-40 microns), a property unmatched by any brittle ceramic.",
  "Wear resistance is high and, critically, gold wears at a rate similar to enamel, preserving occlusal harmony over decades, whereas some ceramics can abrade opposing enamel.",
  "Excellent fatigue and fracture resistance under high occlusal loads; virtually immune to bulk fracture, making it the material of choice in bruxers and for onlays replacing multiple cusps."
])
P("Esthetic", h3)
P("This is the principal weakness: the golden-yellow colour is unacceptable to most patients for visible teeth, "
  "restricting cast gold essentially to posterior teeth, and even there, increasing esthetic demand has reduced "
  "its popularity.", body)
P("Technical / Economic", h3)
bullets([
  "Requires two clinical visits (or CAD-CAM milling in select systems), an impression, a laboratory casting procedure, and meticulous marginal fit verification, adding to chair-side time and cost.",
  "The tooth preparation for cast metal must incorporate specific mechanical retention/resistance form (defined axial wall taper of 2-5 degrees, proximal boxes, isthmus width one-third to one-quarter of intercuspal distance, occlusal reduction of 1-1.5 mm for onlays) since bonding to metal is chemical/mechanical rather than truly adhesive in the conventional cementation technique.",
  "Cost of gold is high and fluctuates with commodity prices; base-metal (Ni-Cr, Co-Cr) alloys are used as a cheaper substitute but carry risk of nickel hypersensitivity, higher hardness that abrades opposing enamel, and inferior corrosion resistance and castability compared with noble alloys."
])
P("4.2 Overall Appraisal of Metallic Restorations", h2)
P("Cast metal inlays/onlays offer unmatched longevity (reported mean survival often exceeding 20-30 years in "
  "long-term recall studies), superior marginal adaptation through burnishing, and forgiving mechanical behaviour. "
  "Their principal limitations are esthetics, the need for more destructive/defined tooth preparation for "
  "retention form, technique sensitivity of casting and cementation, and diminishing patient acceptance in an era "
  "of esthetic dentistry. They are best reserved for posterior teeth with heavy occlusal load, limited esthetic "
  "demand, and where maximal longevity is the primary objective.", body)

# ---------------- 5. NON-METALLIC ----------------
P("5. Non-Metallic Inlays and Onlays: Critical Appraisal", h1)

P("5.1 Composite Resin (Direct and Indirect)", h2)
bullets([
  "<b>Biological:</b> Kind to opposing dentition (wear rate can be matched to enamel with modern nano-hybrid/micro-hybrid resins); no metal ions released; readily repairable intra-orally if a segment fractures or debonds.",
  "<b>Mechanical:</b> Flexural strength and modulus of elasticity are markedly lower than ceramics or metal, making composite prone to marginal chipping, wear, and lower fracture toughness under heavy occlusal load; long-term colour stability and wear resistance remain inferior to ceramics, with a tendency for surface staining and marginal discoloration over 3-5 years.",
  "<b>Esthetic:</b> Good initial shade-matching and translucency; however, water sorption, polymerisation shrinkage stress (mitigated but not eliminated by indirect fabrication and post-cure), and marginal staining reduce esthetic longevity compared with ceramics.",
  "<b>Technical/Economic:</b> Indirect composite inlays/onlays are simpler and cheaper to fabricate than ceramic (can be milled or heat/light-pressure cured in-office or in a laboratory), are kinder to the milling bur and to opposing enamel, and are easily adjusted, polished, and repaired chairside &mdash; a major clinical advantage over ceramic which is brittle and cannot be intra-orally repaired as reliably.",
  "<b>Bonding:</b> Excellent adhesive bond to resin cement (similar substrate chemistry), reducing the reliance on classical mechanical retention form and permitting more conservative, adhesive tooth preparation."
])

P("5.2 Dental Ceramics", h2)
P("Ceramic materials for inlays/onlays have evolved through generations of increasing strength:", body)
bullets([
  "<b>Feldspathic / silicate porcelain</b> &mdash; excellent esthetics and translucency but low flexural strength (~60-100 MPa); technique-sensitive, largely historical for onlays.",
  "<b>Leucite-reinforced glass-ceramic</b> (e.g., pressed/CAD-CAM leucite ceramics) &mdash; improved strength (~120-160 MPa) with very good esthetics; still relatively brittle.",
  "<b>Lithium-disilicate glass-ceramic</b> &mdash; the current workhorse for CAD-CAM inlays/onlays, combining high flexural strength (~360-400+ MPa after crystallisation), favourable translucency, and reliable adhesive bonding via hydrofluoric-acid/silane conditioning.",
  "<b>Zirconia-reinforced lithium silicate</b> &mdash; intermediate strength and esthetics, easier to mill and polish.",
  "<b>Polycrystalline zirconia</b> &mdash; very high flexural strength (900 MPa+) and fracture toughness but lower translucency (improving with newer high-translucency grades) and, importantly, cannot be reliably etched/silanated, making adhesive bonding less predictable; more suited to full crowns than to thin adhesive onlays.",
  "<b>Resin-matrix CAD-CAM ceramics / polymer-infiltrated ceramic network (PICN)</b> &mdash; hybrid materials with an elastic modulus closer to dentine, reducing risk of enamel wear and of brittle fracture, and are easy to mill, adjust, and polish."
])
P("Biological", h3)
P("Ceramics are highly biocompatible, plaque-resistant due to superior surface polish and low surface energy, and "
  "esthetically the closest match to natural enamel in translucency, opalescence, and fluorescence. Ceramic "
  "restorations luted with resin cement after acid-etch/silane treatment achieve marginal seal and a hybrid layer "
  "comparable to enamel-composite bonds.", body)
P("Mechanical", h3)
bullets([
  "High compressive strength but comparatively lower fracture toughness (brittleness) than metal; risk of bulk or marginal fracture increases with inadequate occlusal thickness (generally requiring at least 1.5-2 mm occlusal reduction) or unsupported enamel margins.",
  "Modulus of elasticity of high-strength ceramics (e.g., lithium disilicate, zirconia) can exceed that of dentine, potentially concentrating stress at the tooth-restoration interface if the underlying tooth structure is not adequately supported by a well-bonded resin cement/adhesive layer.",
  "Wear behaviour depends heavily on final surface polish/glaze: a well-polished/glazed ceramic surface is kind to opposing enamel, but a rough, unglazed, or adjusted-and-unpolished ceramic surface can cause significant enamel wear."
])
P("Esthetic", h3)
P("Ceramics remain the gold standard for esthetics among indirect restorations, offering superior colour stability, "
  "translucency, and resistance to staining over time compared with composite resin.", body)
P("Technical / Economic", h3)
bullets([
  "Fabrication requires either conventional laboratory processing (impression, die, pressing/layering, glazing) or chairside/laboratory CAD-CAM milling; both add cost and technical complexity relative to composite or direct restorations.",
  "Adhesive cementation protocol (etching, silanation, careful isolation, resin cement placement, light-curing) is technique-sensitive; failure of the bonding protocol is a common cause of clinical failure (post-operative sensitivity, debonding, secondary caries).",
  "Repair of a fractured ceramic restoration intra-orally is difficult and unreliable compared with composite; replacement is often necessary.",
  "Higher laboratory/milling cost than composite, though generally comparable to or less than cast gold depending on system and region."
])

# ---------------- 6. COMPARATIVE TABLE ----------------
P("6. Comparative Critical Appraisal: Metallic vs Non-Metallic", h1)
header = ["Criterion", "Metallic (Cast Gold / Base Metal)", "Non-Metallic (Ceramic / Composite)"]
rows = [
 ["Esthetics", "Poor (metallic colour); unacceptable anteriorly and often posteriorly for modern patients",
  "Excellent (ceramic) to good (composite); closely mimics enamel/dentine optics"],
 ["Biocompatibility", "High for noble alloys; base-metal alloys carry nickel-sensitisation risk",
  "High; ceramics are chemically inert and plaque-resistant"],
 ["Marginal fit / adaptation", "Excellent - can be burnished to near-perfect closure of margins",
  "Good but margin quality is fixed by fabrication/milling accuracy and cement film; cannot be burnished"],
 ["Wear resistance / effect on opposing enamel", "Wears similarly to enamel; very kind to opposing dentition",
  "Ceramic can abrade opposing enamel if unpolished/unglazed; composite wears somewhat faster than enamel but is gentle on opposing teeth"],
 ["Fracture resistance / toughness", "Very high; ductile, resists bulk fracture even under bruxism",
  "Ceramic is strong in compression but brittle (risk of bulk fracture); composite is tougher than ceramic but weaker overall and prone to wear/chipping"],
 ["Tooth preparation philosophy", "Defined mechanical retention/resistance form; more prescriptive, sometimes more destructive",
  "Adhesive, more conservative preparation; relies on bonding rather than classical retention form"],
 ["Bonding to tooth structure", "Primarily cementation (non-adhesive, e.g. GIC/zinc phosphate) though resin cements can be used",
  "True adhesive bonding via etch/silane/resin cement, reinforcing the remaining tooth structure"],
 ["Repairability", "Cannot be intra-orally repaired if it fails/decements, but rarely fractures",
  "Composite easily repaired chairside; ceramic fracture usually requires remake"],
 ["Longevity (typical reported survival)", "Excellent; often 20-30 years in long-term studies",
  "Good; lithium disilicate/zirconia ceramic onlays commonly report 90%+ survival at 5-10 years; composite somewhat lower due to wear/staining"],
 ["Technique sensitivity", "Casting and burnishing technique-sensitive but forgiving cementation",
  "Bonding protocol highly technique-sensitive; isolation and adhesive steps critical to success"],
 ["Cost", "High and market-dependent (noble metal); base metal cheaper but with biological trade-offs",
  "Variable; composite generally cheapest, ceramic intermediate to high depending on CAD-CAM system"],
 ["Radiopacity / diagnosis", "Highly radiopaque, easy to distinguish from tooth on radiographs",
  "Variable radiopacity; some ceramics/composites may mimic caries radiographically if not adequately radiopaque"],
]
make_table(header, rows, [1.5*inch, 2.5*inch, 2.5*inch])

# ---------------- 7. CLINICAL PERFORMANCE ----------------
P("7. Clinical Performance and Longevity Data", h1)
P("Long-term clinical trials and systematic reviews consistently rank cast gold onlays among the most durable "
  "indirect restorations in dentistry, with annual failure rates below 1% in several long-term recall cohorts. "
  "Ceramic inlays/onlays (particularly lithium-disilicate and leucite-reinforced systems) have shown 5-year "
  "survival rates generally in the 90-98% range and 10-year survival often above 85-90%, with the principal modes "
  "of failure being bulk/marginal fracture and, less commonly, secondary caries or endodontic complications. "
  "Composite resin inlays/onlays show comparable short-to-medium-term survival to ceramic but a higher incidence "
  "of marginal staining, wear, and the need for repair/replacement over longer follow-up (10+ years). Failure "
  "patterns differ meaningfully by material: metallic restorations rarely fracture but may fail through marginal "
  "leakage, secondary caries, or loss of retention over very long time frames; ceramic restorations fail "
  "predominantly by fracture (often related to inadequate thickness or occlusal overload) and less commonly by "
  "debonding; composite restorations fail chiefly by wear, marginal discoloration, and secondary caries.", body)

# ---------------- 8. FACTORS ----------------
P("8. Factors Influencing Material Selection", h1)
bullets([
  "<b>Location and visibility</b> of the tooth (esthetic zone favours ceramic/composite; hidden posterior teeth may tolerate metal).",
  "<b>Occlusal load and parafunction</b> (heavy bruxism favours the toughness of metal or, among ceramics, zirconia-reinforced systems, over brittle glass-ceramics).",
  "<b>Amount of remaining tooth structure</b> and enamel available for adhesive bonding (adhesive ceramic/composite restorations depend on sound enamel margins for reliable bonding).",
  "<b>Patient esthetic demand and budget.</b>",
  "<b>Operator skill, isolation control, and laboratory/CAD-CAM access</b> (adhesive protocols are technique-sensitive and require excellent moisture control, typically with rubber dam).",
  "<b>Opposing dentition</b> (natural teeth vs existing restorations) to judge wear compatibility.",
  "<b>Time and number of appointments available</b> (chairside CAD-CAM ceramic/composite can be completed in a single visit; cast gold traditionally requires a laboratory turnaround)."
])

# ---------------- 9. RECENT ADVANCES ----------------
P("9. Recent Advances and Future Directions", h1)
P("The advent of chairside CAD-CAM systems has substantially narrowed the practical gap between metallic and "
  "non-metallic restorations by allowing same-day fabrication of ceramic and composite inlays/onlays with "
  "increasingly reliable adhesive bonding protocols, digital impressions, and optimised milling algorithms that "
  "reduce marginal discrepancy. Newer hybrid materials (resin-matrix ceramics, PICN) aim to combine the wear "
  "compatibility and repairability of composite with the esthetics of ceramic. Universal, self-etch, and "
  "multi-mode adhesives together with improved resin cements have made the adhesive-retained philosophy for "
  "non-metallic restorations progressively more predictable, while gold alloy usage has correspondingly declined "
  "outside of niche indications (heavy bruxism, patients declining metal-free options, or specific long-term "
  "functional priorities).", body)

# ---------------- 10. CONCLUSION ----------------
P("10. Conclusion", h1)
P("Neither metallic nor non-metallic materials are universally superior; each occupies a defensible clinical "
  "niche once appraised against biological, mechanical, esthetic, and economic criteria. Cast gold alloys remain "
  "unrivalled for pure longevity, marginal adaptability through burnishing, and mechanical compatibility with "
  "opposing enamel, but are esthetically unacceptable to most patients and require more prescriptive tooth "
  "preparation. Non-metallic restorations, particularly high-strength glass-ceramics and modern resin composites, "
  "offer superior esthetics, more conservative adhesive preparation, and (for composite) easy reparability, at the "
  "cost of greater technique sensitivity in bonding and, for ceramics, an inherent risk of brittle fracture if "
  "material thickness or occlusal design is compromised. Rational clinical decision-making therefore requires "
  "matching the material to the specific biomechanical demands of the tooth, the patient's esthetic expectations, "
  "occlusal risk factors, and the operator's technical resources, rather than adopting a single material as a "
  "default choice for every clinical situation.", body)

story.append(Spacer(1, 14))
P("References / Suggested Reading: Sturdevant's Art and Science of Operative Dentistry; Shillingburg's "
  "Fundamentals of Fixed Prosthodontics; contemporary peer-reviewed clinical trials and systematic reviews on "
  "ceramic and composite inlay/onlay survival. (This essay is a synthesis of standard operative dentistry and "
  "prosthodontic principles for academic examination purposes.)", small)

doc = SimpleDocTemplate(OUT, pagesize=A4,
                         leftMargin=1.6*cm, rightMargin=1.6*cm, topMargin=1.6*cm, bottomMargin=1.6*cm,
                         title="Critical Appraisal of Metallic and Non-Metallic Inlays and Onlays")
doc.build(story)
print("PDF built at", OUT)