The periodontal ligament injection: Histological effects on the periodontium in dogs

0099-2399-83/0910-0411/$02.00/0 JOURNAL OF ENDODONTICS Copyright 9 1983 by the American Association of Endodontists

Printed in U.S.A.

VOL. 9, NO. 10, OCTOBER 1983

The Periodontal Ligament Injection: Histological Effects on the Periodontium in Dogs Q. Michael Fuhs, BS, DDS, MBA, William A. Walker III, BS, DDS, MS, Robert W. Gough, DDS, MS, AdvMed, William G. Schindler, AB, DDS, MS, and Kenton S. Hartman, AB, DDS, MSD

This study was undertaken to determine if periodontal tissues were damaged by the periodontal ligament injection administered by a pistol-type syringe, the Peripress. Injection of 2% xylocaine with 1:100,000 epinephrine or normal saline solution or needle insertion without injection were performed at various sites on 12 dogs. Also, one dog was injected with a dye solution only and one untreated dog was included in the study as an additional control. Injected areas were examined immediately posttreatment and 2, 7, 10, 14, 21, and 28 days after treatment. Histological evaluation showed no evidence of any tissue disruptions or inflammatory reactions due to any of the treatment procedures at any of the observation periods.

dividuals with other bleeding disorders, in whom postinjection bleeding may be dangerous (5). 4. It may be used for young children and mentally or physically handicapped persons in whom the risk of postinjection soft tissue trauma to the still anesthetized tongue or lower lip is increased (6). 5. It is well tolerated by the patient. Malamed (7) found that the periodontal ligament injection was preferred by 74% of the patients treated in his study as compared with 26% who preferred the inferior alveolar injection. 6. It is a very safe injection technique. The possibilities of the development of a hematoma or the administration of an intravascular injection are eliminated. Malamed (7) reported that only 2 of the 62 patients who received the periodontal ligament injection in his study complained of any posttreatment discomfort attributable to the injection technique. Ricciardi (8) reported no posttreatment complaints in over 3,000 periodontal ligament injections. Various individuals have questioned the use of the periodontal ligament injection. They questioned whether its use could result in severe and possibly permanent damage to the periodontium due to direct needle trauma or from injecting solutions into the periodontal ligament under heavy pressure. Phillips (9) and Morse (1) have stated that the periodontal ligament injection should be used only if other supplementary injections were unsuccessful. Morse (1) cautioned against its routine use because of potential tissue damage. However, Walton and Garnick (10), in a histological evaluation of the effects of the periodontal ligament injection on the periodontium in monkeys, found only a slight disruption to the periodontium that was confined to the crestal area. This minimal damage showed rapid repair, indicating that the periodontal ligament injection technique produced no permanent damage to the periodontium (10). Walton and Garnick's study (10) utilized a conventional dental anesthetic syringe rather than a pistoltype pressure syringe specifically designed for the administration of the periodontal ligament injection.

The periodontal ligament injection is a technique of administration of a local anesthetic agent directly into the periodontal ligament space. This technique has come into greater use since the introduction in the late 1970's of several new local anesthetic pressuretype syringes specifically designed for the administration of the periodontal ligament injection--the Peripress (Universal Dental Implements, Edison, NJ), the Ligmaject (Healthco, Inc., Dental Division, Boston, MA), and the PDL syringe (Special Products, Inc., Santa Cruz, CA). The periodontal ligament injection offers several advantages: 1. It may be used to obtain profound anesthesia in situations in which conventional techniques are unsuccessful in obtaining adequate anesthesia (1). Walton and Abbott (2), in a clinical evaluation of the periodontal ligament injection in patients who experienced inadequate pulpal anesthesia, found it to be 92% successful in obtaining profound anesthesia. 2. It may be used as a diagnostic aide when attempting to pinpoint pulpalgia by providing singletooth selective anesthesia (3, 4). 3. It may be used for hemophiliac patients, or in411

412

Fuhs et al.

Journal of EndodonUcs

Walton found that the pistol-type syringes generate over two times the pressure of the conventional anesthetic syringe in administering the periodontal ligament injection. We felt further research utilizing a pistol-type syringe was needed to adequately assess the effects of the periodontal ligament injection when administered under increased pressure with the new pistol-type syringes. The purpose of this study was to determine histologically the influence on the periodontal tissues in dogs of the periodontal ligament injection as administered by the Peripress injection syringe. MATERIALS

TABLE1. Periodontal ligament injection regimen for injected dogs

Tooth Max. right central incisor Max. right canine Max. left lateral incisor Man. right central incisor Man. right canine incisor Man. left lateral incisor

Solution Saline

Injection Site Labial

2% Xylocaine Needleinsertion only Saline

Labial Labial Labial and lingual

2% Xylocaine

Labial and lingual

Needleinsertion only

Labialand lingual

AND METHODS

Fourteen healthy 1-yr-old mongrel dogs were used in this study. The dogs were anesthetized with 2.5% Pentothal (0.5 ml/kg), N20 (2.5 L/min), Fluothane (1%), and 02 (2.5 L/min) prior to the administration of the periodontal ligament injections. Twelve of the dogs were all injected similarly as detailed in Table 1 (injected dogs). In addition, one dog (dye dog) was injected with only a dye (India ink-saline mixture at 1:1; Pelikan Drawing Ink, Pelikan A6, D-3000, Hanover 1, Germany). The dye was administered on five different teeth with only a single labial injection. In all 13 dogs alternate incisor teeth were treated to allow adjacent teeth to serve as controls. Also, one untreated dog was included in the study as an additional control (control dog). Injections were administered with a 30-gauge needle parallel to the long axis of the tooth. The injection site was the mesial-distal midpoint of the labial and lingual surfaces. The needle was placed to the point of maximum penetration which was usually about 2 mm past the crest of bone. The bevel was toward the tooth. Upon initiation of the injection, strong back pressure had to be immediately felt or else the injection was stopped, the needle repositioned, and the injection checked again for strong back pressure. Only upon obtaining strong back pressure was the injection administered by expressing 0.36 ml of the appropriate solution by two full compressions of the trigger of the Peripress, after which the needle was immediately withdrawn. The injection technique used on the teeth in which no solution was deposited involved just needle insertion using an identical technique. However, rather than injecting any fluid, the needle was held in place for 10 s and then withdrawn. In each dog we performed anesthetic injections, saline injections, and needle penetration alone. The dogs were sacrificed by an intravenous injection of Euthanesia (Burns-Biotec Laboratories Division, Chromalloy Pharmaceutical, Inc., Oakland, CA). Two dogs each were sacrificed at 2, 7, 10, 14, 21, and 28 days. The dye dog was sacrificed immediately

after injection. The control dog was sacrificed at 10 days. For all of the dogs, block sections of the maxillary and mandibular anterior teeth were immediately removed and placed in 10% formalin. The blocks were decalcified in 5% formic acid, processed, embedded in paraffin, cut at 7/~m, stained with hematoxylin and eosin, and examined histologically for any evidence of tissue disruptions and inflammatory reactions. It should be noted that in this study, no attempt was made to utilize histochemical methods to evaluate other changes that might have been present. Rather, the histological analysis used in this study was limited to looking for any evidence of tissue disruptions and inflammatory reactions. Each tooth included in this study had at least one section examined histologically at the coronal one-third of the root, at midroot, and at the apical one-third of the root. In those instances in which the histological examination showed possible evidence of any histological damage or inflammatory reactions, vai'ying numbers of additional serial sections were prepared and examined. The histological examination was conducted without knowledge of which section was being examined. The histological examination attempted to evaluate the following items: (a) normal appearance of dog periodontium by examination of the control specimens; (b) evidence of histological changes due to the administration of the periodontal ligament injection by comparing the anesthetic injection specimens with the control specimens; (c) evidence of histologial changes due to needle insertion alone; (d) evidence of histological changes solely due to anesthetic solution itself by comparing the saline injection specimens-with the control dog specimens; and (e) dissemination of injection solution by examining the dye dog specimens. RESULTS

The periodontium of the control teeth was uninflamed and exhibited normal morphology (Fig. 1 ), and served as a comparison to the experimental regions.

Vol. 9, No. 10, October 1983

Periodontal Ligament Injection

413

ence between the anesthetic solution and saline solution specimens and those with needle penetrations only (Figs. 4 and 5). There was no evidence of any tissue damage at any

FiG 2. Dye specimen. Cross-section at the apical one-third of the root demonstrating dye within the medullary spaces as well as within the periodontal ligament (hematoxylin-eosin stain; original magnification x50).

FIG 1. Control specimen. Cross-section at midroot demonstrating uninflammed normal periodontal ligament morphology (hematoxylin-eosin stain; original magnification x50). At each observation period injections had been made with either 2% xylocaine with 1 : 1 0 0 , 0 0 0 epinephrine, or with physiological saline, or just needle insertion alone. Upon evaluation, the specimens in each of these groups were similar in appearance. Histological examination of the prepared materials showed no evidence of any tissue damage at any level at any observation period. The results of the histological examination are presented here by observation period: Immediate Posttreatment Observation

Only one specimen was included in this observation period and that was the dog that was injected with the dye. Examination showed a heavy deposition of the dye within the medullary spaces as well as within the periodontal ligament (Fig. 2). Often the dye was found within the medullary spaces and in the soft tissues at a significant distance from the injection site (Fig. 3). Two-day Observations

As with all of the remaining observation periods, two dogs were examined. Again, there was no differ-

FIG 3. Dye specimen. Cross-section at the apical one-third of the root demonstrating the dye within the medulJary spaces and soft tissue at a significant distance from the injection site (hematoxylineosin stain; original magnification x50).

414

Journal of Endodontics

Fuhset al. DISCUSSION

FDG4. Two-day anesthetic injection specimen. Cross-section at midroot demonstrating normal morphology (hematoxylin-eosin stain; original magnification x50). level with the exception of an area of possible injury in one of the saline specimens. This area occurred at the cervical level on the lingual of one of the mandibular incisors. Due to the isolated incidence of this occurrence and the inability to demonstrate this area of possible injury on any additional sections at the site, it was considered a processing artifact; however, the possibility that it was an area of injury due to the periodontal ligament injection could not be absolutely ruled out. Also, a mild focal lymphohistiocytic infiltrate was observed in one of the anesthetic solution sections at the cervical level on the labial of one of the mandibular incisors. Due to its nature, location, and isolated incidence, this infiltrate was considered to be coincidental. Evidence of a needle penetration was found in only one specimen. That occurred at the cervical level on the lingual of a saline specimen.

This study was a histological evaluation of the effects of the periodontal ligament injection administered by a pistol-type syringe instead of a conventional syringe. An evaluation of the periodontal ligament injection administered by a pistol-type syringe was important because it is capable of generating over two times the pressure of a conventional syringe. Numerous investigators have speculated that the additional pressure generated by the pistol-type syringes might produce tissue damage that would not result from administration of the periodontal ligament injection by a conventional syringe. Significantly, this study found no histological evidence of tissue disruptions or inflammatory reactions produced by the periodontal ligament injection administered by the Peripress on dogs. The consistent absence of a visible puncture wound throughout the epithelium was significant as no evidence of detachment of the epithelium from cementum was observed. It is postulated that the needle penetrated the sulcular epithelium and the soft tissue collapsed into the space as the needle was withdrawn or closed shortly after needle withdrawal. A third consideration was that the needle tract was so nondescript that it could not be definitively demonstrated in the histological sections. It was interesting to note the dispersion of the dye solution apically and into the marrow spaces at some distances from the injection site. The wide, seemingly unrestricted, dispersion of the injected solution possibly explains why little or no tissue damage resulted in this experiment. This study has demonstrated that the periodontal ligament injection administered by the Peripress produced no histological evidence of tissue disruptions or inflammatory reactions in dogs. It may be incorrect to assume that the same response would necessarily occur in humans. Such a strict interpretation of the

Seven-, 10-, 14-, 21-, and 28-day Observations All observations at 7, 10, 14, 21, and 28 days showed no evidence of any tissue damage at any level.

FIG 5. Two-day anesthetic injection specimen. Cross-section at midroot demonstrating normal morphology (hematoxylin-eosin stain; original magnification x 100).

Vol. 9, No. 10, October 1983

Periodontal Ligament Injection

results of this study is not possible due to the physiological differences in the periodontal ligament of the dog as compared with that of humans (less dense connective tissue, greater vascularity, etc.). In addition, this study did not make any attempt to evaluate the possible damage to the pulp as the result of the periodontal ligament injection. For the above mentioned reasons, further studies in this area are needed to evaluate completely the efficacy of the periodontal ligament injection.

CONCLUSIONS The periodontal ligament injection administered by a pistol-type syringe, the Peripress, produced no histological evidence of any tissue disruptions or inflammatory reactions in the periodontium of dogs. The opinions expressed herein are those of the authors and are not to be construed as reflecting the views of the United States Air Force or the Department of Defense. Dr. Fuhs was an endodontic resident at Wilford Hall USAF Medical Center, Lackland AFB, TX and is now the chief of endodontics at USAF Langley AFB, VA. Dr. Walker is chairman of the Department of Endodontics at Wilford Hall USAF Medical Center. Dr. Gough is the assistant director of dental services at Wilford Hall USAF Medical Center and is the Military Consultant to the Surgeon General, USAF, for Endodontics. Dr. Schindler was an endodontic resident at Wilford Hall USAF Medical Center and is currently chief of Endodontics at Vandenberg AFB, CA. Dr. Hartman is the chairman of the Department of Oral Pathology at Wilferd Hall USAF Medical Center, and is the Military Consultant to the Surgeon General, USAF, for Oral Pathology. Address requests for reprints to Dr. Walker, Wilford Hall USAF Medical Center/SGDN, Lackland AFB, TX 78236.

415

References 1. Morse DR. Clinical endodontology. Springfield, IL: Charles C Thomas, 1974. 2. Walton RE, Abbott BJ. The periodontal ligament injection: a clinical evaluation. J Am Dent Assoc 1981 ;103:571-5. 3. Simon DE III. Intraligamentary anesthesia--State of the art in selective anesthesia for diagnosis, Table Clinic, American Association of Endodontists Annual Session, 1982, Phoenix, AZ. 4. Simon DE III, Jacobs TL, Senia ES, Walker WA III. Intraligamentary anesthesia as an aid in endodontic diagnosis. Oral Surg 1982;54:77-8. 5. Jastak JT, Yagiela JA. Regional anesthesia of the oral cavity. St. Louis: CV Mosby Co., 1981. 6. Matamed SF. Handbook of local anesthesia. St. Louis: CV Mosby Co., 1980. 7. Malamed SF. The periodontal ligament (PDL) injection: an alternative to the inferior alveolar nerve block. Oral Surg 1982;53:117-21. 8. Ricciardi A. Intraligamentary anesthesia. The Pennsylvania Acad Gen Dent 1981 ;5(2). 9. Phillips WH. Anatomic considerations in local anesthesia. J Oral Surg 1943;1:112-21. 10. Walton RE, Garnick JJ. The periodontal ligament injection: histologic effects on the periodontium in monkeys. J Endodon 1982;8:22-6.

EDITOR'S NOTE:

Re: The Periodontal Ligament Injection: Histological Effects on the Periodontium in Dogs (Fuhs et al.)

There is evidence that the periodontal ligament injection may be detrimental to pulpal microcirculation. While this is of no consideration where pulpotomies are to be performed, the possibility of these effects should be taken into consideration when this type of anesthesia is used for operative procedures on teeth with vital pulps. References 1. Kim S, Trowbridge H, Edwal L. J Dent Res (in press).

Erratum Illustrations (Figs. 1 to 3, 5, 6, and 8) used in the case report, Orthodontic External Resorption--Endodontic Considerations, published in the June 1983 issue of the Journal had been previously published in the May 1983 issue of the American Journal of Orthodontics in the article, An Endodontic-Orthodontic Technique for Esthetic Stabilization of Externally Resorbed Teeth.