You and your eligible dependents shall pay no more than the following amounts for these covered dental services, subject to all other plan limitations:
| Code | Procedure | You will pay |
| Restorative Services | ||
| Amalgam (silver) filling and composite (white) filling, once every 24 months on the same surface of the same tooth | ||
| D2140 | Amalgam – one surface, primary or permanent |
17.00
|
| D2150 | Amalgam – two surfaces, primary or permanent |
22.00
|
| D2160 | Amalgam – three surfaces, primary or permanent |
26.00
|
| D2161 | Amalgam – four or more surfaces, primary or permanent |
31.00
|
| D2330 | Resin-based composite – one surface, front tooth | 21.00 |
| D2331 | Resin-based composite – two surface front tooth | 27.00 |
| D2332 | Resin-based composite – three surfaces, front teeth | 32.00 |
| D2335 | Resin-based composite – four or more surfaces, front teeth | 41.00 |
| D2390 | Resin-based composite crown, front baby teeth only | 55.00 |
| D2391 | Resin-based composite – one surface, posterior |
26.00
|
| D2392 | Resin-based composite – two surfaces, posterior |
50.00
|
| D2393 | Resin-based composite – three surfaces, posterior |
61.00
|
| D2394 | Resin-based composite – four or more surfaces, posterior |
71.00
|
| Onlays, per tooth, once every 84 months | ||
| D2543 | Onlay – metallic – three surfaces |
300.00
|
| D2544 | Onlay – metallic – four or more surfaces |
400.00
|
| D2643 | Onlay – porcelain/ceramic – three surfaces |
150.00
|
| D2644 | Onlay – porcelain/ceramic – four or more surfaces |
350.00
|
| Crowns, once per tooth every 84 miles due to fracture or decay: | ||
| D2710 | Crown – resin-based composite (indirect) |
150.00
|
| D2740 | Crown – porcelain/ceramic substrate |
425.00
|
| D2750 | Crown – porcelain fused to high noble metal |
425.00
|
| D2751 | Crown – porcelain fused to predominantly base metal |
325.00
|
| D2752 | Crown – porcelain fused to noble metal |
375.00
|
| D2753 | Crown – porcelain fused to titanium and titanium alloys |
325.00
|
| D2780 | Crown – 3/4 cast high noble metal |
140.00
|
| D2781 | Crown – 3/4 cast predominantly base metal |
385.00
|
| D2782 | Crown – 3/4 cast noble metal |
385.00
|
| D2783 | Crown – 3/4 porcelain/ceramic |
385.00
|
| D2790 | Crown – full cast high noble metal |
425.00
|
| D2791 | Crown – full cast predominantly base metal |
325.00
|
| D2792 | Crown – full cast noble metal | 375.00 |
| D2794 | Crown – titanium |
425.00
|
| Recement – once per item per lifetime when performed by same dental office | ||
| D2910 | Recement inlay, onlay, or partial coverage restoration |
30.00
|
| D2915 | Recement cast or prefabricated post and core |
30.00
|
| D2920 | Recement crown |
30.00
|
| D2929 | Prefabricated porcelain/ceramic crown – primary tooth | 85.00 |
| D2930 | Prefabricated stainless steel crown – primary tooth | 85.00 |
| D2931 | Prefabricated stainless steel crown – permanent tooth | 85.00 |
| D2934 | Prefabricated esthetic coated stainless steel crown, primary tooth | 85.00 |
| D2940 | Protective retoration – direct placement of a restorative material to protect the tooth and/or tissue form, once per tooth per 60 months | 30.00 |
| D2941 | Interim therapeutic restoration – primary dentition | 30.00 |
| D2950 | Core buildup, including any pins, once per tooth every 84 months due to fracture or decay |
80.00
|
| D2951 | Pin retention, per tooth not per pin, only with fillings |
18.00
|
| Post and core, in addition to crown, once per tooth every 84 months | ||
| D2952 | Post and core in addition to crown, indirectly fabricated | 140.00 |
| D2954 | Prefabricated post and core in addition to crown |
110.00
|
| D2971 | Additional procedures to construct new crown under existing partial denture framework, once every 84 months in addition to crown | 85.00 |
| D2976 | Band stabilization, per tooth | 10.00 |
| D2980 | Crown repair necessitated by restorative material failure once every 12 months, only after 24 months of initial insertion | 65.00 |
| D2982 | Onlay repair necessitated by restorative material failure once every 12 months, only after 24 months of initial insertion | 65.00 |
| Endodontics | ||
| Endodontic treatments are covered once per tooth per lifetime | ||
| D3220 | Therapeutic pulpotomty (excluding final restoration), baby teeth only | 30.00 |
| D3221 | Gross pulpal denridement, age 13 and under | 30.00 |
| D3310 | Root canal therapy, anterior tooth (excluding final restoration) |
165.00
|
| D3320 | Root canal therapy, bicuspid tooth (excluding final restoration) |
180.00
|
| D3330 | Root canal therapy, molar tooth (excluding final restoration) | 210.00 |
| D3332 | Incomplete endodontic therapy; inoperable, unrestorable or fractured tooth, subject to review |
50.00
|
| D3346 | Retreatment of previous root canal therapy, anterior tooth, by report |
200.00
|
| D3347 | Retreatment of previous root canal therapy, bicuspid tooth, by report |
300.00
|
| D3348 | Retreatment of previous root canal therapy, molar tooth, by report | 400.00 |
| Apicoectomy, once per root per lifetime | ||
| D3410 | Apicoectomy/periadicular surgery – anterior |
115.00
|
| D3421 | Apicoectomy/periadicular surgery – bicuspid (first root) | 135.00 |
| D3425 | Apicoectomy/periadicular surgery – molar (first root) |
140.00
|
| D3426 | Apicoectomy/periadicular surgery (each additional root) |
90.00
|
| D3430 | Retrograde filling – once per root per lifetime | 40.00 |
| D3450 | Root amputation – once per root per lifetime |
80.00
|
| D3920 | Hemisection (including any root removal), not including root canal therapy |
85.00
|
| Periodontics | ||
| Periodontic treatments are once every 36 months unless otherwise noted | ||
| D4210 | Gingivectomy or gingivoplasy – four or more contiguous teeth or tooth bounded spaces per quadrant |
112.00
|
| D4211 | Gingivectomy or gingivoplasy – one to three teeth or tooth bounded spaces per quadrant | 42.00 |
| D4240 | Gingival flap procedure, including root planing – four or more contiguous teeth or tooth bounded spaces per quadrant |
150.00
|
| D4241 | Gingival flap procedure, including root planing – one to three contiguous teeth or tooth bounded spaces per quadrant |
80.00
|
| D4249 | Clinical crown lengthening – hard tissue, once every 84 months | 170.00 |
| D4260 | Osseous surgery (including flap entry & closure) – four or more contiguous teeth or tooth bounded spaces per quadrant | 220.00 |
| D4261 | Osseous surgery (including flap entry & closure) – one to three contiguous teeth or tooth bounded spaces per quadrant |
155.00
|
| D4263 | Bone replacement graft – first site in quadrant | 100.00 |
| D4264 | Bone replacement graft – each additional site in quadrant | 85.00 |
| D4265 | Biologic materials to aid in soft tissue and osseous tissue regeneration |
75.00
|
| D4270 | Pedicle soft tissue graft procedure |
190.00
|
| D4273 | Sub epithelial connective tissue grafts procedure, per tooth (including donor site) |
200.00
|
| D4275 | Soft tissue allograft | 190.00 |
| D4277 | Free soft tissue graft procedure (including donor site surgery), first tooth or edentulous tooth position in graft |
165.00
|
| D4278 | Free soft tissue graft procedure (including donor site surgery), each additional tooth or edentulous tooth position in same graft site | 82.00 |
| D4283 | Autogenous connective tissue graft procedure (including recipient surgical site and donor material), first tooth, implant or edentulous tooth position | 200.00 |
| D4285 | Non-autogenous connective tissue graft procedure (including recipient surgical site and donor material) – each additional contiguous tooth, implant or edentulous tooth position in the same graft site | 100.00 |
| D4341 | Periodontal scaling and root planing – four or more disease teeth per quadrant, once every 24 months | 40.00 |
| D4342 | Periodontal scaling and root planing – one to three disease teeth per quadrant, once every 24 months |
25.00
|
| D4355 | Full mouth debridement to enable comprehensive evaluation and diagnosis, once per lifetime |
30.00
|
| Prosthodontics – removable | ||
| Prosthodontics include routine post-delivery care and are once every 84 months unless otherwise noted: | ||
| D5110 | Complete denture – maxillary, once every 60 months | 150.00 |
| D5120 | Complete denture – mandibular, once every 60 months | 150.00 |
| D5130 | Immediate complete denture – maxillary, once every 60 months |
150.00
|
| D5140 | Immediate complete denture – mandibular, once every 60 months | 150.00 |
| D5211 | Maxillary partial denture – resin base |
250.00
|
| D5212 | Mandibular partial denture – resin base |
250.00
|
| D5213 | Maxillary partial denture – cast metal framework with resin denture bases |
410.00
|
| D5214 | Mandibular partial denture – cast metal framework with resin denture bases |
410.00
|
| D5221 | Immediate maxillary partial denture – resin base (inluding any conventional clasps, rests, teeth) | 250.00 |
| D5222 | Immediate mandibular partial denture – resin base (including any conventional clasps, rests and teeth) | 250.00 |
| D5223 | Immediate maxillary partial denture – cast metal framework with resin denture bases (including any conventional clasps, rests and teeth) | 410.00 |
| D5224 | Immediate mandibular partial denture – cast metal framework with resin denture bases (including any conventional clasps, rests and teeth) | 410.00 |
| D5225 | Maxillary partial denture – flexible base | 360.00 |
| D5226 | Mandibular partial denture – flexible base | 360.00 |
| D5227/D5228 | Immediate partial denture – flexible base, maxillary/mandibular | 250.00 |
| D5282/5283 | Removable unilateral partial denture – one piece cast metal (including clasps and teeth), maxillary/mandibular |
175.00
|
| D5284 | Removable unilateral partial denture – one piece flexible base (including clasps and teeth) – per quadrant |
175.00
|
| D5286 | Removable unilateral partial denture – one piece resin (including clasps and teeth) – per quadrant | |
| D5410 | Adjust complete denture – maxillary | 15.00 |
| D5411 | Adjust complete denture – mandibular |
15.00
|
| D5421 | Adjust partial denture – maxillary |
15.00
|
| D5422 | Adjust partial denture – mandibular | 15.00 |
| Repairs are once every 12 months unless otherwise noted: | ||
| D5511 | Repair broken complete denture base, mandibular |
40.00
|
| D5512 | Repair broken complete denture base, maxillary |
40.00
|
| D5520 | Replace missing or broken teeth complete denture (each tooth) | 30.00 |
| D5611 | Repair resin denture base, mandibular | 30.00 |
| D5612 | Repair resin denture base, maxillary | 30.00 |
| D5621 | Repair cast framework, mandibular |
50.00
|
| D5622 | Repair cast framework, maxillary |
50.00
|
| D5630 | Repair or replace broken clasp |
50.00
|
| D5640 | Replace broken teeth – per tooth |
30.00
|
| D5650 | Add tooth to existing partial denture | 40.00 |
| D5660 | Add clasp to existing partial denture |
45.00
|
| D5670 | Replace all teeth and acrylic on cast metal framework (maxillary), once every 84 months | 225.00 |
| D5671 | Replace all teeth and acrylic on cast metal framework (mandibular), once every 84 months | 225.00 |
| Rebase procedures are once every 36 months, Reline procedures are once every 12 months: | ||
| D5710 | Rebase complete maxillary denture |
100.00
|
| D5711 | Rebase complete mandibular denture | 100.00 |
| D5720 | Rebase maxillary partial denture |
100.00
|
| D5721 | Rebase mandibular partial denture |
100.00
|
| D5725 | Rebase hybrid prosthesis |
100.00
|
| D5730 | Reline complete maxillary denture (chairside) | 25.00 |
| D5731 | Reline complete mandibular denture (chairside) | 25.00 |
| D5740 | Reline maxillary partial denture (chairside) |
25.00
|
| D5741 | Reline mandibular partial denture (chairside) | 100.00 |
| D5750 | Reline complete maxillary denture (laboratory) | 25.00 |
| D5751 | Reline complete mandibular denture (laboratory) |
25.00
|
| D5760 | Reline maxillary partial denture (laboratory) | 25.00 |
| D5761 | Reline mandibular partial denture (laboratory) |
25.00
|
| D5765 | Soft liner for complete or partial removable denture – indirect |
125.00
|
| Prosthodontics – fixed | ||
| Procedure codes D6010 and D6013 are eligible for a separate “implant annual plan maximum”. | ||
| D6010 | Surgical placement of implant body, endosteal implant (this code includes second stage surgery and placement of healing cap where indicated) |
750.00
|
| D6013 | Surgical placement of mini implant | 400.00 |
| D6056 | Prefabricated abutment (includes modification & placement) | 300.00 |
| D6057 | Custom abutment (includes placement) |
350.00
|
| D6058 | Abutment supported porcelain/ceramic crown | 500.00 |
| D6059 | Abutment supported porcelain fused to metal crown (high noble metal) | 500.00 |
| D6060 | Abutment supported porcelain fused to metal crown (base metal) | 500.00 |
| D6061 | Abutment supported porcelain fused to metal crown (noble metal) | 500.00 |
| D6062 | Abutment supported cast metal crown (high noble metal) | 500.00 |
| D6063 | Abutment supported cast metal crown (base metal) | 500.00 |
| D6064 | Abutment supported cast metal crown (noble metal) | 500.00 |
| D6065 | Implant supported porcelain/ceramic crown | 500.00 |
| D6066 | Implant supported porcelain fused to metal crown (titanium, titanium alloy, high noble metal) | 500.00 |
| D6067 | Implant supported metal crown (titanium, titanium alloy, high noble metal) | 500.00 |
| D6069 | Abutment supported retainer for porcelain fused to metal FPD (high noble metal) | 500.00 |
| D6070 | Abutment supported retianer for porcelain fused to metal FPD (predominantly base metal) | 500.00 |
| D6071 | Abutment supported retianer for porcelain fused to metal FPD (noble metal) | 500.00 |
| D6082 | Implant supported crown – porcelain fused to predominantly base alloys | 500.00 |
| D6083 | Implant supported crown – porcelain fused to noble alloys | 500.00 |
| D6084 | Implant supported crown – porcelain fused to titanium and titanium alloys | 500.00 |
| D6086 | Implant supported crown – predominantly base alloys | 500.00 |
| D6087 | Implant supported crown – noble alloys | 500.00 |
| D6088 | Implant supported crown – titanium and titanium alloys | 500.00 |
| D6089 | Accessing and retorquing loose implant screw, per screw | 50.00 |
| D6092 | Recement implant/abutment supported crown | 40.00 |
| D6093 | Recement implant /abutment supported fixed partial denture | 30.00 |
| D6094 | Abutment supported crown – titanium | 500.00 |
| D6097 | Abutment supported crown – porcelain fused to titanium and titanium alloys | 500.00 |
| D6098 | Abutment supported crown – porcelain fused to predominantly base alloys | 325.00 |
| D6099 | Implant supported reetainer for FPD porcelain fused to noble alloys | 375.00 |
| D6100 | Surgical removal of implant body | 45.00 |
| D6104 | Bone graft at time of implant placement | 100.00 |
| D6105 | Removal of implant body not requiring bone removal or flap elevation | 26.00 |
| D6120 | Implant supported retainer – porcelain fused to titanium and titanium alloys | 375.00 |
| D6121 | Implant supported retainer for FPD – predominantly base alloys | 375.00 |
| D6122 | Implant supported retainer for metal FPD – noble alloys | 375.00 |
| D6123 | Implant supported retainer for metal FPD – titanium and titanium alloys | 375.00 |
| D6194 | Abutment supported retainer crown for FPD (titanium) | 500.00 |
| D6195 | Abutment supported retainer – porcelain fused to titanium and titanium alloys | 500.00 |
| D6197 | Replacement of restorative material used to close access opening of screw retained implant | 26.00 |
| D6210 | Pontic – cast high noble metal | 425.00 |
| D6211 | Pontic – cast predominantly base metal | 325.00 |
| D6212 | Pontic – cast noble metal | 375.00 |
| D6214 | Pontic – titanium | 425.00 |
| D6240 | Pontic – porcelain fused to high noble metal | 425.00 |
| D6241 | Pontic – porcelain fused to predominantly base metal | 425.00 |
| D6242 | Pontic – porcelain fused to noble metal | 375.00 |
| D6243 | Pontic – porcelain fused to titanium and titanium alloys | 375.00 |
| D6245 | Pontic – porcelain/ceramic | 425.00 |
| D6545 | Retainer – cast metal for resin bonded fixed prosthesis (Maryland bridge) | 125.00 |
| D6549 | Resin retainer – for resin bonded fixed prothesis | 125.00 |
| D6740 | Crown – porcelain/ceramic | 425.00 |
| D6750 | Crown – porcelain fused to high noble metal | 425.00 |
| D6751 | Crown – porcelain fused to predominantly base metal | 325.00 |
| D6752 | Crown – porcelain fused to noble metal | 375.00 |
| D6753 | Retainer crown – porcelain fused to titanium and titanium alloys | 400.00 |
| D6783 | Retainer Crown 3/4 – porcelain/ceramic | 425.00 |
| D6784 | Retainer Crown 3/4 – titanium and titanium alloys | 425.00 |
| D6790 | Crown – full cast high noble metal | 425.00 |
| D6791 | Crown – full cast predominantly base metal | 325.00 |
| D6792 | Crown – full cast noble metal | 425.00 |
| D6794 | Crown – titanium | 425.00 |
| D6930 | Recement fixed bridge | 30.00 |
| D6980 | Fixed partial denture repair, by report | 65.00 |
| Oral Surgery | ||
| D7111 | Extraction, coronal remnants – decidous tooth | 20.00 |
| D7140 | Extraction, erupted tooth or exposed root (elevation and/or forceps removal) | 26.00 |
| D7210 | Surgical removal of erupted tooth requiring removal of bone and/or sectioning of tooth, including elevation of mucoperiosteal flap if indicated | 45.00 |
| D7220 | Removal of impacted tooth – soft tissue | 65.00 |
| D7230 | Removal of impacted tooth – partially bony | 100.00 |
| D7240 | Removal of impacted tooth – completely bony | 110.00 |
| D7241 | Removal of impacted tooth – completely bony, with ususual surgical complications | 125.00 |
| D7250 | Surgical removal of residual tooth roots (cutting procedure) | 45.00 |
| D7251 | Coronectomy – intentional partial tooth removal, impacted teeth only | 65.00 |
| D7280 | Surgical access of an unerupted tooth | 125.00 |
| D7283 | Placement of device to facilitate eruption of impacted tooth, once per tooth per lifetime, allowed with orthodontics only | 40.00 |
| D7284 | Excisional biopsy of minor salivary glands | 100.00 |
| D7310 | Alveoplasty in conjunction with extractions – four or more teeth or tooth spaces, per quadrant, once per lifetime | 50.00 |
| D7311 | Alveoplasty in conjunction with extractions – one to three teeth or tooth spaces, per quadrant, once per lifetime | 40.00 |
| D7320 | Alveoplasty not in conjunction with extractions – four or more teeth or tooth spaces, per quadrant, once per lifetime | 85.00 |
| D7321 | Alveoplasty not in conjunction with extractions – one to three teeth or tooth spaces, per quadrant, once per lifetime | 70.00 |
| D7340 | Vestibuloplasty – ridge extension, once per arch per lifetime (secondary epithelialization) | 100.00 |
| D7510 | Incision and drainage of abscess – intraoral soft tissue (involves incision through mucosa) | 40.00 |
| D7511 | Incision and drainage of abscess – intraoral soft tissue complicated (includes drainage of multiple fascial spaces) | 40.00 |
| D7961 | Buccal/labial frenectomy (frenulectomy) | 82.00 |
| D7962 | Lingual frenectomy (frenulectomy) | 82.00 |
| D7963 | Frenuloplasty, once per site, per lifetime | 82.00 |
| D7971 | Excision of periocoronal gingival, subject to review | 30.00 |
| Other | ||
| D9110 | Palliative (emergency) treatment dental pain, minor procedures, three occurences in 6 months, not allowed on same day as sedative filling | 16.00 |
| D9120 | Fixed partial denture sectioning | 22.00 |
| Intravenous sedation or general anesthesia, subject to review, up to a total of 1 hour | ||
| D9222 | Deep sedation/general anesthesia – first 15 minutes | 25.00 |
| D9223 | Deep sedation/general anesthesia – each 15 minute increment | 25.00 |
| D9239 | Intravenous moderate (conscious) sedation/anesthesia – first 15 minutes | 25.00 |
| D9243 | Intravenous moderate (conscious) sedation/anesthesia – each 15 minute increment | 25.00 |
| D9310 | Consultation, per session | 20.00 |
| D9941 | Athletic mouthguard – once per patient (age 18 and under, every 24 months) | 75.00 |
| D9942 | Repair and/or reline of occlusal guard, only after 6 months after insertion | 25.00 |
| D9943 | Occlusal guard adustment | 20.00 |
| D9944 | Occlusal guards, by report – hard appliance, full arch | 80.00 |
| D9945 | Occlusal guards, by report – soft appliance, full arch | 20.00 |
| D9946 | Occlusal guards, by report – hard appliance, partial arch | 40.00 |
| D9995 | Teledentistry – synchronous, real time encounter | 0.00 |
| Other Orthodontic Services |
||
| D8698 | Recement or re-bond fixed retainer – maxillary | 80.00 |
| D8699 | Recement or re-bond fixed retainer – mandibular | 80.00 |
| D8701 | Repair of fixed retainers, includes reattachment – maxillary | 60.00 |
| D8702 | Repair of fixed retainers, includes reattachment – mandibular | 60.00 |
| D8703 | Replacement of lost or broken retainer – maxillary | 250.00 |
| D8704 | Replacement of lost or broken retainer – mandibular | 250.00 |
| Orthodontic Services: | ||
Orthodontic benefits under the MPE EPN plan are based on a very unique plan design and specific guidelines must be followed. Patients must receive treatment from an EPN plan-approved orthodontist to receive benefit.
All orthodontic cases must be pre-approved. Your MPE EPN Plan approved orthodontist must submit a pre-treatment estimate to the MPE Unit at Delta Dental of Massachusetts prior to the start of treatment. Once the treatment is reviewed, you will receive an Explanation of Benefits (EOB) showing the approved level of treatment. Cases not approved prior to the start of treatment may not be a covered benefit.
The level of treatment approved will be based on the appropriate American Dental Association definition, case complexity and length of treatment. The Fund pays the orthodontist in periodic payments.
| You will pay | |
| Orthodontic Diagnostic Workup | 175.00 |
| Orthodontic Treatment (Class I, Class II, and Class III Malocclusion | |
| Case 1: Limited |
890.00
|
| Case 2: Comprehensive | |
| Level A |
1,140.00
|
| Level B |
1,310.00
|
| Level C |
1,480.00
|
| Level D |
1,650.00
|
| Level E |
1,820.00
|
| Level F |
2,710.00
|
- Treatment not received by an EPN plan approved orthodontist is not a covered benefit.
- If you had a Case 1 service at any time prior to being enrolled in the EPN Plan, and regardless of what dental insurance you had at that time, the amount paid by your prior insurance will be deducted from any payment approved for a MPE EPN Case 2. If the payment made for these prior services exceeded the MPE EPN approved payment for the Case 2 level, no payment will be made.
- Patients must agree to complete their treatment with the same orthodontist. The patient co-payment will not be guaranteed if you change to a new orthodontist during the course of treatment, nor can any payments be made by the Fund to a second orthodontist.
Important Note: The estimated co-payments listed above re only applicable for traditional braces. They are not applicable if the patient is receiving Invisalign (clear aligners). The orthodontist may charge the patient the additional costs involved with Invisalign treatment. The patient should discuss this option with the orthodontist prior to starting treatment.
Limitations and Exclusions:
- Orthodontic treatment that began prior to the date on which you became eligible for benefits is not a covered service.
- Each orthodontic case is considered once per lifetime, per patient, regardless of what coverage, if any, the patient had on the original treatment date.
- If you change your dental plan enrollment or terminate coverage before the orthodontic treatment is completed or before all Fund periodic payments have been made, no further payments will be made by the Fund.
- No additional coverage will be provided for patients that do not comply with the agreed-upon treatment plan. Successful orthodontic treatment requires the patient to keep regularly scheduled appointments, to maintain good oral health, and to follow the specific instructions of the orthodontist.
- All mail-order or self-administered orthodontic treatment kits are not a covered benefit under the MPE Fund Plans.
Preventive dental care is very important in maintaining good oral health while undergoing orthodontic treatment. Please discuss appropriate care with your dentist, including things you can do at home (e.g. xylitol products, fluoride rinses) to prevent future tooth decay.